09 23 00/NGC09 26 13/NGCGold Bond ®

BRAND

Plaster ResourceManual

2

SECTION PAGE

Lath & Plaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Gypsum Plaster Base and Metal Lath . . . . . . . . . . . . . . . . . . .4

Conventional Plaster Accessories . . . . . . . . . . . . . . . . . . . . . . .5

Basecoat Plasters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Finish Plasters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Problems & Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Veneer Plaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Veneer Plaster System Components . . . . . . . . . . . . . . . . . . .14

Veneer Plaster Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Problems & Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

How to use this ManualDesigned for contractors, architectsand specifiers, this useful manualcontains a broad range of helpfulinformation about our lath andplaster systems and veneer plasters.

Since conventional lath and plasterdiffers from veneer plaster, we’vesimplified the manual by dividing itinto two distinct sections.

The first section contains descriptionsof our gypsum plaster systems includinglath, metal accessories and plasters.You’ll also find construction recom-mendations to help you get themost from this conventional finish.

The second section, devoted toveneer plaster, features descriptionsof our products including Uni-Kal®,X-KALibur® and Kal-Kote®, alongwith a comparison of one-coat andtwo-coat systems.

In both sections, we look at uniqueconditions common to plaster finishes,and we recommend solutions tothese problems.

We’ve even included a glossary ofplaster terms and definitions.

For technical inquiries, contact ourTechnical Services Department at1-800-NATIONAL (628-4662), orfax 1-800-FAX-NGC1 (329-6421).You can also access our Internethome page at nationalgypsum.comor nationalgypsum.com/espanol.

Note: Further information on ourplaster products is available inNational Gypsum Company’s Gypsum Construction Guide.

Table of Contents

3

Lath & Plaster

DescriptionConventional gypsum lath andplaster systems have long beenconsidered the industry standard inwall construction.

Ideal for both residential and commercial applications, lath andplaster systems provide smooth,high quality wall surfaces, regardlessof framing alignment.

Lath and plaster deliver exceptionalbeauty and durability in interiorpartitions and non-loadbearingexterior walls. Conventional plastersystems are also commonly usedas the panel material for radiantheating systems in ceilings.

When used with expanded metallath, conventional plasters create amechanical bond for maximumstrength and durability. Gypsumplasters are also excellent forsculpting, casting decorativeobjects, and historic restoration.

General UsesGypsum plaster systems are suit-able for all interior plasteringexcept areas directly exposed tofree water or severe moisture. Lathand plaster is not recommendedfor exterior applications such ascarports, soffits and open porches.

Gypsum plasters are non-com-bustible and act to prevent passageof intense heat from fire for extend-ed periods. For specific fire resistanceratings, see National Gypsum’sGypsum Construction Guide.

Features/Benefits� Provides a smooth, high quality

surface

� Requires no joint taping and finishing

� Resists nail pops better thangypsum wallboard

� Enhances overall wall strength

� High impact and abrasion resistance

� Masks framing components andmechanical service areas

Selecting PlasterBasesNational Gypsum Company manu-factures all of the most commontypes of gypsum base plaster andfinishing plaster.

These products perform well in appearance, structural ability,sound isolation and fire enduranceratings, allowing architects todesign virtually any number of ceilings and partitions.

PerformanceThe relative performance of gypsumand metal lath varies depending on the type of construction.Whenplaster on metal lath forms a mem-brane, as in a suspended ceiling orhollow partition, it’s more subject tocracking than plaster on gypsumlath. On solid partitions, metal lathis generally less subject to plastercracking than gypsum lath.

Recommendations� Control joints should be installed

in ceilings without perimeterrelief with a maximum distancebetween joints of 30' with amaximum undivided area of900 sq. ft. With perimeter relief,the maximum distance betweenjoints is 50' with a maximumundivided area of 2500 sq. ft.On side walls, control jointsshould be installed every 30'.

� Where dissimilar plaster basesadjoin, use strip-metal lath with15 lb. felt paper between themetal lath and underlying base.

� Carefully inspect all lath and fur-ring before plastering to ensureadherence to job specificationsand good practice standards.

� Select from the suggested specifications that accompanythe description of each system.

PRODUCT SHELF LIFEStorage/

Product Shelf Life

Two-Way Hardwall 3 months

Gypsolite® Plaster 3 months

Gauging Plaster 3 months

Molding Plaster 3 months

09 23 00/NGC

4

DIAMOND MESH LATH

Used as a plaster base and rein-forcement on almost all types ofwalls and ceilings, over wood orsteel framing, flat or curved surfaces.

SELF-FURRING DIAMOND MESH LATH

Used extensively in stucco work, asa plaster reinforcement over interiormasonry walls, and in steel columnfireproofing. The self-furring dimpleshold the metal lath 1/4" awayfrom the surface to be plastered.

1/8" FLAT RIB LATH

Designed to meet the demand forrigid expanded metal lath used asa plaster base in all types of work.Widely used as reinforcement forbasecoat in ceramic tile work.

3/8" RIB LATH

The 3/8" rib lath is used for ceilingsunder steel joist construction andmetal reinforced concrete floors. Itis also recommended for concreteslab floors over steel joists.

Kal-Kore® BRAND Plaster Base Metal Lath Products*

Gypsum Plaster Base and Metal Lath

DescriptionKal-Kore® BRAND is a tapered edgegypsum wallboard plastering basehaving a blue absorptive face paper surface. Although specificallydesigned as a base for veneer plaster,it also provides an excellent basefor conventional basecoat plasterssuch as Gypsolite or Two-WayHardwall.

Technical DataKal-Kore is available in two basictypes: Regular and Fire-Shield Type X.Kal-Kore is 4' wide and is supplied in8' through 16' lengths.Thicknessesare as follows:

Regular: 3/8" and 1/2".

Fire-Shield: 1/2" Fire-Shield G,5/8" Fire-Shield, 5/8" Fire-ShieldG, produced to meet ASTM C 588/C 1396.

Note: Installation of gypsum lathand metal lath shall be in accor-dance with ASTM C 841. Do notuse 3/8" Kal-Kore Plaster Base withconventional basecoat plasters.

* Metal products are not manufactured by National Gypsum Company.

Conventional Plaster Accessories*

* Metal products are not manufactured by National Gypsum Company.

DOUBLE V EXPANSION JOINT

Minimizes cracking in large plasterareas. Also provides ground toassure proper plaster or stuccothickness.

DOUBLE V CORNEREXPANSION JOINT

Similar in design to Double Vexpansion joint but preformed tofit corner angles. Galvanized steelor zinc.

EXPANSION JOINT

Designed to relieve stresses inlarge gypsum and portland cementplaster areas. Material will expandand contract to allow for 1/8" to5/8" opening. Incorporates aweather resistant joint. Galvanizedsteel or zinc.

EXPANDED FLANGE SQUARE CASING

Has short, 90 degree return at plastersurface, serving as a plastering stop.

EXPANDED CORNERBEAD

The 2-1/2" expanded flange ends1/4" from the nose of the beadproviding reinforcement where needed most.

BULL NOSE CORNERBEAD

Reinforces exterior corners whererounded edges are required. Nose3/4" radius. Galvanized steel.

WIDE FLANGE EXPANDEDCORNERBEAD

Has 3-3/16" expanded flanges foruse on masonry, beams and forcolumn fireproofing. Galvanizedsteel.

L RUNNER

Perforated – Ceiling or floor support for 2" solid lath and plaster partition.

Plain – Ceiling support for 2" solid wallboard partition using 1"shaftliner.

COLD ROLLED STEELCHANNEL

Used as studs for attaching metallath in 2" solid partitions. For furringor runners in suspended ceilings.

BEAM FURRING CLIP

Used to attach lath to flanges ofsteel beams, joists and columns.Tempered spring steel.

5

6

Basecoat Plasters

DescriptionGold Bond® Two-Way HardwallPlaster is a basecoat plaster whichrequires the job site addition of anaggregate and water to provideworking qualities and is designedfor interior use over all acceptedplaster bases. It may be applied byhand or used through pump/ sprayplastering machines.

Features/BenefitsControlled UniformityTwo-Way Hardwall Plaster is set-stabilized and adjusted for marketrequirements and seasonal changes.When mixed with sand or otheraggregate it has uniform workingqualities and excellent spread.

Technical Data

Technical Data

StrengthTwo-Way Hardwall Plaster properlyproportioned with aggregate formsa hard, durable base for the finishcoat. Its high tensile and compres-sive strength results in increasedresistance to minor structural movements, impacts and abrasions.

Fire ResistanceTwo-Way Hardwall Plaster is essentially mineral in compositionand will not support combustion.

Gold Bond® BRANDTwo-Way Hardwall Gypsum Plaster

DescriptionGold Bond® Gypsolite® is a light-weight gypsum basecoat plastermixed at the mill with correctlysized and proportioned perliteaggregate, requiring only the addition of water on the job. It is manufactured to be trowel-applied over gypsum plaster base,and in some cases metal lath (see LIMITATIONS.)

Features/BenefitsUniform Strength andHardnessUniformity is assured through exactproportioning and thorough mixingof graded perlite and gypsum plas-ter at the mill. Gypsolite provides auniform base for the finish coat.

LightweightGypsolite weighs less than half as much as sanded gypsum plaster,thus reducing the dead-load onframing.

High Insulating ValueGypsolite has a “k” factor of 1.5which provides about 3-1/2 times theinsulating value of sanded plaster.

Fire ResistanceGypsolite has excellent fire-resistivequalities and generally provides fireratings higher than sanded plaster.

LimitationsWhen used over metal lath, a sandfloat finish should be specified. Asmooth-trowel finish is not recom-mended since the combination of arelatively soft (perlite aggregated)basecoat and a hard (smooth-trowel lime/gauging) finish has thepotential for cracking and spallingof the finish coat.

Specification ReferenceASTM Designation C 28, “GypsumPlasters”.

Bag Weight 80 lbs. (36.3 kg)25 lbs. (11.3 kg)

Specification Reference ASTM Designation C 28, “GypsumPlasters”.

Bag Weight 100 lbs. (45.4 kg)

Gold Bond® BRANDGypsolite® Plaster

AGGREGATE PROPORTION AND ESTIMATED COVERAGECoverage, Sq. Ft. Thick-

Aggregate Sq.Yds. /Ton (Sq. M.) nessProportions Plaster Base (Sq. M./Metric Ton) per Bag In. (mm)

Sanded Gypsum Lath 175-220 80-100 7/16"1:2-1/2 (161-203) (7-9) (11.1)

Sanded Gypsum Foil 175-220 80-100 7/16"1:2-1/2 Back Lath (161-203) (7-9) (11.1)

Sanded Metal Lath 90-125 40-55 9/16"*1:2-1/2 (83-115) (4-5) (14.3)*

Sanded Brick & Clay Tile 175-220 80-100 9/16"1:3 Concrete Block (161-203) (7-9) (14.3)

*Measured from face of lath.NOTE: Sanded 1:2-1/2 means 1 part plaster to 2-1/2 parts sand by weight.

GYPSOLITE ESTIMATED COVERAGECoverage, Sq. Ft. Thickness

Sq. Yds. per Ton (Sq. M.) In.Plaster Base (Sq. M/Metric Ton) per Bag (mm)

Gypsum Lath and 140-155 50-55 7/16"Gypsum Foil Back Lath (129-143) (4-5) (11.1)

Metal Lath 65-80 25-30 9/16"*(60-74) (2-3) (14.3)*

*Measured from face of lath.WEIGHT COMPARISON OF BASECOAT PLASTERSDry Set Mortar Weight Sanded 1:3 Gypsolite

Weight lbs. per cu. ft. (kg/m3) 120 (1922) 50 (801)

Lbs./yd.2 (kg/m2) 3/8" (9.5 mm) thick 34 (18) 14 (8)Lbs./yd.2 (kg/m2) 1/2" (12.7 mm) thick 45 (24) 19 (10)Lbs./yd.2 (kg/m2) 5/8" (15.9 mm) thick 56 (30) 24 (13)Lbs./yd.2 (kg/m2) 3/4" (19.0 mm) thick 67 (36) 29 (16)

Wet Mortar Weight

Weight lbs. per cu. ft. (kg/m3) 140 (2243) 69 (1105)

77

Finish Plasters

Gold Bond Gauging Plaster, quick setor slow set type, is designed for usewith finish lime. It is specially ground,calcined gypsum, which readily mixeswith water and lime putty. Properproportioning is essential, sincegauging adds strength and hardnessto the finish surface by reinforcingthe plastic non-setting lime againstshrinkage and cracking.A finish coatof gypsum gauging plaster and finishlime, job mixed 2 parts hydrated limeto 1 part plaster by weight, isdesigned primarily for interiorsmooth trowel application over a

For a mill-mixed finish plaster, useKal-Kote Smooth Finish, Kal-KoteTexture Finish Plaster, Uni-KalVeneer Plaster or X-KALibur

Extended Set Veneer Plaster.Requires the addition of wateronly. See page 17.

Bag WeightQuick Set: 100 lbs./45.4 kg (50 lb./22.7 kg bags available in limited areas)

Slow Set: 100 lbs./45.4 kg (50 lb./22.7 kg bags available in limited areas)

Bag Weight100 lbs./45.4 kg (50 lbs./22.7 kgbags available in limited areas)

Technical Data

Mill-Mixed Finish Plasters

Technical Data

gypsum plaster basecoat. Smoothfinish plasters should be applied at athickness of not more than 1/16".Texture finishes should be applied ata thickness of not more than 1/8".

Specification ReferenceComplies with ASTM DesignationC 28.

Gold Bond® BRANDGypsum Gauging Plaster (Super White)

Gold Bond Moulding Plaster is a verywhite, finely ground gypsum, primarilyused for all kinds of ornamental plaster work. Because of its lowexpansion, excellent strength andhardness, it is specially adaptable forcasting in rubber, gelatin and othertypes of moulds. For casting purposes,only water is added. For run-in-placeornamental work, such as cornices,the moulding plaster is used with limeputty,mixed 2 parts lime to 1 partmoulding plaster by weight.

Specification ReferenceComplies with ASTM DesignationC 59.

Note: Application of plaster shallbe in accordance with ASTM C 842.

Gold Bond® BRANDGypsum Moulding Plaster (Super White)

GYPSUM GAUGING PLASTERMethod of Application Coverage*

Trowel Finish 1000-1400 sq. yds./Ton (921-1290 m2/Metric Ton)225-315 sq. ft./Bag (21-29 m2/Bag)

*Based on one part plaster to two parts hydrated lime.

*See page 17 for additional information.

GYPSUM MOULDING PLASTERMethod of Application Coverage*

Trowel Finish 1000-1400 sq. yds./Ton (921-1290 m2/Metric Ton)225-315 sq. ft./Bag (21-29 m2/Bag)

*Based on one part plaster to two parts hydrated lime.

MILL-MIXED FINISH PLASTERS*Method of

Product Application Coverage*

Kal-Kote Smooth Finish Trowel 650-750 sq. yds./Ton (598-645 m2/Metric Ton)

Kal-Kote Texture Finish Trowel 650-750 sq. yds./Ton (598-645 m2/Metric Ton)

Uni-Kal and X-KALibur Trowel 600-665 sq. yds./Ton (553-613 m2/Metric Ton)

PHYSICAL PROPERTIES OF BASECOAT PLASTERS (TYPICAL TEST RESULTS PER ASTM C 472)Plaster Gypsolite Two-Way Hardwall to Two-Way Hardwall Two-Way HardwallProperties Regular Sand by Weight and Vermiculite and Perlite

Regular Masonry Regular Masonry

Mix Mill Mix 1:1 1:2 1:3 100 lbs. (45.4 kg) 100 lbs. (45.4 kg) 100 lbs. (45.4 kg) 100 lbs. (45.4 kg)2 cu. ft. (.06 m3) 3 cu. ft. (.08 m3) 2 cu. ft. (.06 m3) 3 cu. ft. (.08 m3)

Approximate Compressive 900 1600 1150 750 500 300 900 650Strength lbs. per sq. in. (kPa) (6201) (11024) (7923) (5168) (3445) (2067) (6201) (4479)

Approximate Tensile 160 250 190 120 130 90 160 100Strength lbs. per sq. in. (kPa) (1102) (1722) (1309) (827) (896) (620) (1102) (689)

8

Lath & Plaster Problems and Solutions

Conditions/Causes/Prevention/Correction

Plaster problems are rarely caused bya gypsum plaster product deficiency.In general, most conventional plasterconstruction problems can be classified into one of the followingcategories.

� Cracks*

� Surface defects, blemishes, stains

� Weak or soft plaster

� Bond failure

� Finish coat problems

� Working qualities and settingaction

� Painting plaster

The cause(s) of these generally arethe result of:

� Conditions relating to plaster set

� Poor quality or incorrect propor-tioning of aggregate

� Structural movement

� Improper mixing, application orthickness of basecoat or finis

� Incorrect or improper lathing orsubstrate

� Dirty mixing equipment

� Environmental job conditions

� Poor or improper plasteringpractices and workmanship

*Conventional plaster, although not con-sidered to be a structural member, is notdelicate construction and can endure con-siderable abuse without cracking. However,cracks can occur when excessive externalforces caused by structural or componentmovement over which the plaster is appliedare transmitted to the plaster or by extremeenvironmental changes.

Condition

CRACKS

Connected Vertical And Horizontal CracksOccurring At SomewhatRegular Intervals,Usually In A Stepped Or Grid Pattern

Cracks Around AndOver Openings Such AsDoors Or Windows

Fine Cracks OccurringIn A Random PatternUsually Less Than 6" Apart. ShrinkageCracks, Crazing,Alligatoring, ChipCracks

Random Cracks In WallOr Ceiling, GenerallyRunning Full Length OfWall Or Width OfCeiling. May AdjoinOther Cracks And AreGenerally WidelySpaced

Construction

Plaster applied over gypsum or metal lath.

Plaster over masonry, cementblock, gypsum tile or gypsum,wood or other sheet lath.

1. Basecoat over masonry,cement block, etc.

2. Lime putty finish overgypsum basecoat.

Plaster over any substrate.

Probable Cause

1. Plaster too thin.2. Weak plaster (too much

or improper aggregate.)3. Lath improperly applied.

1. Poor construction of lintel,door bucks improperlyconstructed or installed.

2. Plaster too thin.3. Failure to use reinforcing.4. Expansion of wood or

metal framing.5. Weak plaster, too much

aggregate.

1. Basecoat too rich,insufficient aggregate.

2. Basecoat too dry whenfinish applied – excessivesuction.

3. Insufficient or slowsetgauged finish.

4. Finish applied too thick.5. Insufficient troweling of

finish.

Structural movement.

Preventive Action

Properly install lath, use properly sized and propor-tioned aggregate and applyplaster to the requiredthickness.

Follow proper construction installation practices.

Follow proper plasteringpractices.

Use a properly designedand installed constructionsuch as a suspended orfloating plaster system.

Corrective Action

1. Apply another coat ofplaster to proper thickness.

2. Remove defective plasterwork and replace withproperly proportionedplaster.

3. Check Lathing Specifica-tions, remove and reapplylath properly and replaster.

1. Patch cracked areas.2. Apply coat of plaster to

proper thickness.3. Remove plaster and provide

expanded metal rein-forcement and replaster.

4. Remove plaster, providecontrol joints, replaster.

5. No correction – removeand replaster.

1. Remove plaster and redoproperly.

2. Prepare basecoat by sprayingwith water to decrease suction.

3. Strip finish, replaster withproper gauging.

4. Strip finish and correctlyrefinish.

5. Strip finish and tightly scratch,apply 1/32" - 1/16" thick.

Repair cracks.Large Cracks: Remove plas-ter about 6" on each side ofthe crack down to the sub-strate. Place a strip of metallath in the cleared area, wetwith water and replaster.Small Cracks: Open thecrack slightly, wet and fillflush with a setting typejoint compound.

9

Condition

CRACKS (cont.)

Cracks At Wall OrCeiling Angles

Cracks Not Due To AnyOf The PreviouslyMentioned Causes AndAre Not The Result OfStructural Movement

SURFACE DEFECTS

Fuzz (Efflorescence) OnSurface,White Or Colored,Is Water Soluble And CanBe Removed By Brushing

Streaky Discoloration

Streaked Finish, JoiningsShowing, Dirty Areas

Blisters On Finish Coat(Entrapped air betweenfinish and substrate)

Projections On SurfaceWhich Fall Out LeavingCraters Or Pits. May HaveFine Cracks RadiatingFrom The Center

Construction

1. Plaster over gypsum lath.2. Plaster over masonry.

1. Plaster over metal or gypsum lath.

2. Plaster over metal or gypsum lath on steelframing.

Basecoat or finish coat overmasonry or concrete substrate.

Lime putty finishes gaugedwith gauging plaster orKeene’s cement.

Finish plaster over any sub-strate.

Gauged lime putty or millmixed gypsum plaster trowelfinishes.

Finish or basecoat plasterscontaining lime.

Probable Cause

1. a. Thin plaster.b. Failure to use expandedmetal reinforcement.c. Structural movement.

2. Failure to tie wallstogether.

1. a. Metal lath too light.b. Metal lath not lappedor properly tied.c. Thermal shock.

2. a. Improper spacing offraming members.b. Thermal shock.

Efflorescence – water solublesalts are deposited on thesurface of the plaster as themasonry or concrete dries.

1. Use of too much waterwhile troweling.

2. Improperly/poorly mixedlime and gauging material.

3. Dirty tools, water, or mixingequipment.

4. Efflorescence.

1. Too much water usedwhile troweling.

2. Use of dirty water duringtroweling.

1. Basecoat too green (wet).2. Insufficient suction.3. Too much water used

while troweling.4. Insufficient gauging.5. Troweling before suffi-

cient take-up.

Unslaked lime or foreignmatter in the plaster whichhydrates and expands afterapplication.

Preventive Action

1. a. Be sure proper plaster-ing grounds are in place.b. Always apply expandedmetal reinforcement in allinterior angles.c. Follow proper construc-tion practices.

2. Follow proper constructionpractices.

Follow proper constructionpractices.

Fur wall away from themasonry or concrete prior toplastering.

1. Use proper amount of water while troweling.

2. Thoroughly mix the limeand gauging.

3. Use only clean tools, mixingequipment and water.

4. See prevention for FUZZYsurface.

Use only the proper amountof clean water during trow-eling.

1/2. Allow basecoat to drysufficiently to developproper suction.

3. Dash water on surfacesparingly during troweling.

4. Use proper proportions oflime putty and gauging.

5. Allow plaster to take-upsufficiently before troweling.

Use Type S hydrated lime orproperly soak lime to insureproper hydration.

Corrective Action

1. a. Apply second coat ofplaster to proper thickness.b. Cut out plaster andpatch.c. Patch cracks.

2. Patch cracks.

1. a/b. Remove lath andplaster, apply properweight lath and replaster.c. Patch cracks.

2. a. Remove plaster, properlyspace framing and replaster.b. Patch plaster.

Eliminate the source ofmoisture.

1–3. Paint plastered sur-faces with a good qualitypaint as recommendedby the paint manufactur-er.

4. See correction for FUZZYsurface.

Prime and paint surfacewith a good quality paint asrecommended by the paintmanufacturer.

Remove blistered finish andreplaster.

Remove the core of thecrater or pits and patchwith finish plaster or readymix joint compound.

10

Condition

WEAK OR SOFT PLASTER

Soft, White, ChalkySurface

Soft, Dark, DampPlaster Surface

Weak, Soft Plaster, DueTo Improperly Propor-tioned Aggregate

Separation Of BasecoatFrom Gypsum Lath

Separation Of BasecoatFrom Metal Lath

Separation Of BasecoatFrom Unit Masonry

Construction

Basecoat over any plaster base.

Basecoat over any substrate.

Gypsum basecoat over anyplaster base.

Basecoat over gypsum lath.

Basecoat over metal lath.

Basecoat over unit masonry.

Probable Cause

Usually occurring duringdry, hot weather. Too muchventilation has removed waterfrom the plaster before ithas set. Called “dry-out”.

1. DAMP WEATHER - toolittle ventilation duringdamp weather, waterremaining in plaster toolong after set hasoccurred, “Sweat-Out”.

2. FREEZING WEATHERCONDITIONS – FROZENPLASTER

1. Too fine or poor aggre-gate grade.

2. Too much aggregate.

1. Too much or improperaggregate used.

2. Frozen plaster.

1. Too much or improperaggregate.

2. Frozen plaster.3. Scratch coat too thin.

1. Excessive suction of themasonry base.

2. Masonry base has a non-absorbent or glazedsurface.

3. Efflorescence present onthe masonry base.

Preventive Action

Screen openings to minimizedrafts during dry, hot weatherand spray the surfaces andfloors with water during thesetting period.

1. Maintain proper heatingand ventilating prior to,during and after plastering.

2. Maintain minimum 55˚Fprior to, during and afterplastering and provideadequate ventilation untilplaster is dry.

Use only aggregate meetingASTM specification. Properlyproportion aggregate andplaster.

1. Use only proper andASTM-specified plaster/aggregate proportions.

2. Maintain a minimum temper-ature of 55˚F in the buildingprior to, during and afterapplication and provideadequate ventilation.

1. Use only proper andASTM-specified plaster/aggregate proportions.

2. Maintain a minimum tem-perature of 55˚F in thebuilding prior to, during andafter application and pro-vide adequate ventilation.

1. Dampen the masonry toreduce suction.

2. Roughen the masonrysurface to provide a keyfor the plaster.

3. Eliminate the source ofmoisture causing the efflo-rescence. Fur away fromthe masonry surface andapply lath over the furring.

Corrective Action

Spray dried out areas withwater or a solution of alum(1 lb. alum per 3 gallons ofwater).

1. Dry plaster by ventilatingand heating. If conditionhas existed for too longit cannot be corrected.Plaster must be removedand replastered.

2. Close building, heatbuilding until plaster setsand continue heatingand ventilating after set.

No correction – remove theplaster and replaster.

No correction – remove theplaster and replaster.

No correction – remove theplaster and replaster.

No correction – remove theplaster and replaster.

BOND FAILURE OF BASECOAT

11

Condition

Separation Of GypsumPlaster From MonolithicConcrete Surface

Brown Coat PlasterSeparating FromScratch Coat Plaster

FINISH COAT PROBLEMS

Gauged Lime PuttyFinish Coat SeparatingFrom Brown Coat Plaster

Gypsum Sand Float OrTrowel Finish SeparatingFrom Brown Coat

Finish Coat Weak, Soft

Lime/Gauging Finish –Tough, Short WorkingOr Lumpy Lime Putty

Set Not Uniform

Construction

Basecoat over monolithicconcrete.

Three-coat plaster work.

Gauged lime finish over basecoat.

Gypsum sand finish over basecoat.

Gypsum finish over basecoat.

Gauged lime finish overbasecoat.

Gypsum finish overbasecoat.

Probable Cause

Concrete bonding agent notapplied.

1. Weak scratch coat plaster.2. Failure to provide adequate

mechanical keying toscratch coat.

1. Brown coat too weak,too smooth, too wet (toolittle suction) or too dry(too much suction).

2. Finish applied improperly.3. Incomplete hydration of

finish lime.

1. Brown coat too weak.2. Brown coat too dry.3. Brown coat too smooth.

1. Insufficient gauging plaster used.

2. Retempered finish coat.3. Inadequate or insufficient

troweling of the finish.

1. Old material, warehousedtoo long or improperly.

2. Lime improperly mixed orsoaked.

3. Low temperatures.

1. Improper gauging plasterused.

2. Temperature conditionstoo hot or cold.

Preventive Action

Apply plaster bonding agentper ASTM specification –before application of plaster.

1. See preventive actionsunder weak, soft plaster.

2. Do not over trowelscratch coat; rake orbroom scratch coat to pro-vide mechanical keying.

1. Make sure brown coat isproperly prepared toreceive finish.

2. Apply finish, taking pre-cautions to follow recom-mended practices.

3. Use only Type S hydratedlime and mix accordingto recommendations.

Make certain that the browncoat is sound, not overly dryand has adequate roughnessto provide keying to the finish.

1. Use proper proportionsof gauging to lime putty.

2. Do not retemper plasterthat has started to set.

3. Lime putty finishes mustbe troweled sufficientlyto densify the finish anddevelop proper strength.

1. Use only fresh lime whichhas been properly ware-housed.

2. Mix and/or soak limeaccording to supplier’srecommendations.

3. Maintain proper temper-ature above 55˚F prior to,during and after plastering.

1. Use either Quick or Slowset gauging in the properproportions.

2. Maintain proper temper-ature above 55˚F prior to,during and after plastering.

Corrective Action

No correction – remove theplaster and replaster.

No correction – remove theplaster and replaster.

1. No correction – removefinish coat, correct condi-tion of brown coat andreplaster.

2/3. No correction – removefinish coat and replaster.

1. No correction – removefinish, correct brown coatcondition and replaster.

2. No correction – removefinish, spray brown coatwith water to reduce suc-tion and replaster.

3. No correction – removefinish, roughen browncoat to provide adequatekeying and replaster.

No correction – remove theplaster and replaster.

There is no correction forthese occurrences.

There is no correction forthese occurrences.

BOND FAILURE OF BASECOAT (cont.)

12

Condition

Finish Coat Works Hard

Slow Plaster Sets – Not Set After Five OrSix Hours

Plaster Sets Too QuicklyTo Be Darbied Or SetsIn Mortar Box Or OnThe Board

Plaster Works Hard OrShort, Will Not Spread,Will Not Carry ProperAmount Of Aggregate

Construction

Gypsum finish overbasecoat.

Basecoat plaster over anysubstrate.

Basecoat plaster over anysubstrate.

Basecoat plaster over anysubstrate.

Probable Cause

1. Basecoat plaster too dry.2. Finish coat mixed too

stiff.

1. Retarding action of aggregate.

2. Retarding action of waterbeing used.

3. Old plaster set lengtheneddue to aging.

1. Tools and mixing equip-ment not free of set plaster.

2. Dirty or contaminatedsand or water.

3. Plaster too old or becamewet in storage or on thejob site.

4. Plaster being mixed toolong.

1. Plaster is old or storedunder poor conditions.

2. Too much or improperaggregate being used.

Preventive Action

Follow good plasteringpractices.

Use only proper plasteraggregate, potable waterand fresh plaster.

Keep tools and mixingequipment clean, use onlypotable water and cleansand for mixing. Use freshplaster which has beenstored properly. Followgood plastering practices.

Use only fresh, properlystored plaster.

Corrective Action

1. Apply finish coat overgreen base or spray thedry base lightly withwater before finishing.

2. Use correct amount of waterwhen mixing finish coat.

1/2. Obtain good sand andwater or acceleratemixes.

3. Replace with fresh plasteror accelerate mixes.

1–3. Judiciously useretarder to slow setting,clean equipment andobtain clean water andsand.

4. Reduce plaster mixingtime.

1. Blend equal parts offresh and old plaster.

2. Use proper aggregate atproper proportions.

FINISH COAT PROBLEMS (cont.)

WORKING QUALITIES AND SETTING ACTION

Painting PlasterVarious job conditions such as suction differences, wet or only partially drywalls, and reactions between paint and lime may cause unsatisfactorypaint finishes, particularly on new construction.

Alkali-resistant primers specifically formulated for use over new plaster willpermit decorating with oil or latex type paints.

Quality paint products should be used and manufacturers’ recommendationsfollowed. Finished plaster should be painted or covered to conceal possiblediscoloration. The paint system should be suitable for use over plaster surfaces that contain lime.

It is essential that plaster be sound and completely dry before painting.Conventional plaster may require 30 to 60 days to fully dry.

13

Veneer Plaster

DescriptionVeneer Plaster Systems consist of a4' wide gypsum plastering basewith a special, highly absorptivepaper surface that is covered withthinly troweled, special purposeplasters. Two basic types of veneerplaster are available: Uni-Kal and X-KALibur, which are one-coatplaster system products; and Kal-Kote, a two-coat plaster system.The gypsum plaster base, Kal-Kore,is erected in the same manner forboth systems. Both veneer plastersystems can be specified for virtuallyall types of partition and ceilingconstructions including wood orsteel framing or furring and masonry.For both residential and commercialbuildings, either type of veneerplaster system produces a wall morenail-pop resistant than drywalland, when properly installed, morecrack resistant than conventionallath and plaster.

Features/BenefitsThe advantages of veneer plasterover other commonly used partitionand ceiling systems include:

� Rapid installation which reducesoverall construction time.

� Appearance and surface of conventional plaster at lowercost than regular plastering.

� High resistance to cracking,nail-popping, impact and abrasion failure.

� Mill-mixed plaster componentshelp assure uniform installationperformance and finished jobquality.

One-Coat SystemFeatures/Benefits(Uni-Kal®/X-KALibur® BRAND)

� Requires only one plasteringmaterial on the job.

� Slightly lower in-place cost thantwo-coat system.

� Can be applied directly to concrete block.

� X-KALibur is formulated to haveextended set characteristics beyondtraditional Uni-Kal setting times.

Two-Coat SystemFeatures/Benefits(Kal-Kote® BRAND)

� Kal-Kote System may be usedfor plaster-embedded electricradiant heating cable systems.

� Same application techniques asfor conventional plaster.

� Greater crack resistance thanone-coat systems.

� Can be applied directly to concrete block.

Limitations� Not recommended for exterior

use or where subject to weath-ering, direct water contact ortemperature exceeding 125˚F(52˚C) for extended periods oftime.

� Framing spacing is limited andpartition heights are reduced incomparison with some standardconstructions.

� Provides less rigidity than simi-lar standard plaster systems.

� When Uni-Kal/X-KALibur will beapplied, do not install Kal-Koretoo far in advance of plasteringsince Uni-Kal/X-KALibur bondcan be adversely affected if faceof Kal-Kore has become fadedfrom light. If Kal-Kore has beenfaded, apply Kal-Kote BasePlaster or a plaster bondingagent to obtain good bond.

� All are designed for trowelapplication. Veneer Plasters arenot suitable for conveyance orapplication by conventionalplastering machines.

� Compared to conventional plasters, Veneer Plaster Systemsare more subject to beading(ridging) and cracking at thejoints under rapid drying condi-tions such as those caused bylow humidity, high temperatureand/or high draft exposure.

� All provide a base over whichpaints or other finishes shouldbe applied.

� Do not use a polyethylene vapor retarder unless structureis ventilated adequately duringapplication of veneer plasters.

� A bonding agent must beapplied to monolithic concrete prior to application ofeither system.

� Do not sand finished plaster.

PRODUCT SHELF LIFEStorage/

Product Shelf Life

X-KALibur 12 months

Kal-Kore Basecoat 12 months

Uni-Kal 12 months

Kal-Kote Smooth 12 months

Kal-Kote Texture 12 months

09 26 13/NGC

14

Veneer Plaster System Components

Kal-Kore® BRAND

Kal-Kore is a tapered edge gypsumwallboard plastering base having ablue absorptive face paper surfacedesigned to permit rapid trowelapplication and strong bond ofKal-Kote, Uni-Kal and X-KALiburplasters. Also available foil backedor Fire-Shield (Type X). Kal-Kore ismanufactured to conform to ASTMSpecification C 588/C 1396 andCSA A82.27.

Gold Bond® BRANDHi-Abuse® XP®

Kal-Kore Plaster BaseHi-Abuse BRAND Kal-Kore Fire-Shield Type X Plaster Base panelsconsist of a fire resistive type Xgypsum core encased in a heavy,blue absorptive face paper designedto permit rapid trowel applicationand strong bond of Uni-Kal VeneerPlaster and strong liner paper onthe back side. Hi-Abuse XP Kal-KoreFire-Shield Type X Plaster Base features a specially formulated coreto provide fire resistance ratings

when used in tested systems aswell as greater resistance to surfaceindentation. Long edges of thepanels are tapered to allow jointsto be reinforced and concealedwith Kal-Mesh Tape and Uni-KalPlaster.

Gold Bond® BRANDHi-Impact® XP®

5/8" Kal-Kore Fire-Shield Type XHi-Impact BRAND Kal-Kore Fire-ShieldType X plaster base is a taperededge panel consisting of a fireresistive Type X gypsum coreencased in a blue absorptive facepaper designed to permit rapidtrowel application and strong bondof Kal-Kote, Uni-Kal and X-KALibur plasters and strong liner paper on theback side. Lexan film is bonded to theback side of the panel to provideadditional impact/ penetrationresistance. Kal-Kore Fire-Shield TypeX Hi-Impact XP is manufactured toconform to ASTM specification C588/C 1396 and Federal SpecificationSS-L-30D Type VI Grade X (Fire-Shield).

SPECIFICATIONSSize Thickness Edge Pcs./Bdl.

4'x8' 3/8" (9.5 mm) Tapered 2(1219 mm x 2438 mm)

4'x8', 12' 1/2" (12.7 mm) Tapered 2(1219 mm x 2438 mm, 3657 mm) 1/2" (12.7 mm)

FSK-G

4'x8', 12' 5/8" (15.9 mm) Tapered 2(1219 mm x 2438 mm, 3657 mm) FSK

4'x8', 12' 5/8" (15.9 mm) Tapered 2(1219 mm x 2438 mm, 3657 mm) FSK

Hi-Abuse

4'x8', 12' 5/8" (15.9 mm) Tapered 2(1219 mm x 2438 mm, 3657 mm) FSK

Hi-Impact

** Alternate: On walls, 1-1/4" (31.8 mm) Type W screws are spaced 12" (305 mm) whenframing is 24" o.c. (610 mm), 16" (406 mm) when framing is 16" o.c. (406 mm).

SPACING OF FRAMING OR FURRINGType of MaximumFraming or Kal-Kore SpacingFurring Thickness on center

Wood 3/8" (9.5 mm) 16" (406 mm)*1/2" (12.7 mm) 24" (610 mm)**5/8" (15.9 mm) 24" (610 mm)

Metal*** 3/8" (9.5 mm) N.A.1/2" (12.7 mm) 16" (406 mm)5/8" (15.9 mm) 24" (610 mm)

N.A.–Not Approved.* Bound edge of Kal-Kore must be at right angles to framing for ceiling or walls.

** Bound edge of Kal-Kore must be at right angles to joists. 16" (406 mm) maximum spacing for bound edge of Kal-Kore parallel to joists.

***On ceilings, screw furring channel [7/8" (22.2 mm) depth] shall span 48" (1219 mm) maximum. Resilient furring channel [1/2" (12.7 mm) depth] shall span 24" (610 mm) maximum. For greater spans, 1-5/8" (41.3 mm) Screw Studs may be used as Ceiling Furring Channels provided they are secured with flanges up (open side up) at spans not to exceed: 6' (1829 mm) at 12" o.c. (305 mm) spacing, 5'6" (1676 mm) at 16" o.c. (406 mm) spacing and 5' (1524 mm) at 24" o.c. (610 mm) spacing.

FASTENERS FOR ATTACHING KAL-KOREFraming Kal-Kore Fastener Fastener Spacing

Screw 1/2" (12.7 mm) Type S Screws 12" o.c. Max.Studs & 1" (25.4 mm) for single layer (305 mm)Furring 5/8" (15.9 mm) 1-5/8" (41.3 mm) for two-ply

3/8" (9.5 mm) 1-1/4" (31.8 mm) annular Ceiling 7" o.c.or 4d box nails** (178 mm) Max.

Wood 1/2" (12.7 mm) 1-1/4" (31.8 mm) annular Sidewall 8" o.c.Framing or 5d box nails** (203 mm) Max.

5/8" (15.9 mm) 1-3/8" (34.9 mm) annularor 6d box nails**

15

Uni-Kal®/X-Kalibur®

Uni-Kal and X-KALibur are singlecomponent veneer plasters forapplication over Gold Bond taperededge 1/2" Regular or 5/8" Fire-ShieldKal-Kore, 5/8" Hi-Abuse Kal-Kore,5/8" Kal-Kore Hi-Impact or as afinish coat over Kal-Kote base.When applied in a thin coat 3/32"thick and troweled to a smoothfinish, they provide a durable,abrasion-resistant surface for furtherdecoration. X-KALibur has a longerextended working time. Uni-Kaland X-KALibur may be worked to avariety of textured finishes.

Uni-Kal and X-KALibur applied notexceeding 1/16" may be used as afinish coat over a 3/32" coat ofKal-Kote Base Plaster for a totalminimum thickness of 1/8".

Strength of Uni-Kal and X-KALiburprovides a surface resistant toabrasion, cracking and nail-pops.

Fire Resistance

Fire ratings equivalent to those ofdrywall systems can be obtained byapplying the corresponding Kal-Koretype and thickness over the sameframing member size and spacingwith the same fasteners and 3/32"of Uni-Kal or X-KALibur.

Specification Reference

ASTM Designation C 587.

Bag Weight

50 lbs. (22.7 kg)

Coverage (est.)*

3/32" on Kal-Kore Base, 600-665sq. yds. per ton (135-150 sq. ft. perbag). One coat to level overmasonry, 300-350 sq. yds. per ton(70-80 sq. ft. per bag).

*Coverage estimates over conventionalplasters are approximately the same asover Kal-Kore Base Board for conventionalplasters.

Kal-Kote®

Base PlasterKal-Kote Base Plaster is a speciallydesigned high strength basecoatplaster for application 1/16" minimum thickness over Kal-Kore,masonry or monolithic concretethat has been treated with a bonding agent.

Strength of Kal-Kote Base is sub-stantially greater than that exhibitedby typical sanded basecoat plaster.

Fire Resistance

Fire ratings equivalent to those ofdrywall systems can be obtained byapplying the corresponding Kal-Kore type and thickness over thesame framing member size andspacing, with the same fasteners.The total plaster thickness shouldbe a minimum of 1/8".The minimum1/8" thickness is achieved byapplying a finish not exceeding1/16" over 3/32" of Kal-Kote BasePlaster.

Specification Reference

ASTM Designation C 587.

Bag Weight

80 lbs. (36.3 kg)

Coverage (est.)

1/16" on Kal-Kore Base, 425-475sq. yds. per ton (150-170 sq. ft. perbag). One coat to level overmasonry, 225-275 sq. yds. per ton(80-100 sq. ft. per bag).

Kal-Kote®

Smooth FinishKal-Kote Smooth Finish is designedto provide a white smooth trowelfinish using conventional plasteringtechniques. Apply not exceeding1/16" over Kal-Kote Base.

Requires the addition of wateronly. It may also be used as a finishfor conventional basecoat plasters.Small amounts of commercialretarder may be cautiously used toslow the setting time when usedover conventional basecoat plasters.

Bag Weight

50 lbs. (22.7 kg)

Coverage (est.)*

1/16" coat troweled on Kal-KoteBase Plaster, 650-700 sq. yds. perton (145-160 sq. ft. per bag).

Kal-Kote®

Texture FinishKal-Kote Texture Finish is designedto provide a variety of decorativesurfaces using common plasteringtechniques. Applied as a 1/16" finish coat over Kal-Kote Base. Itrequires the addition of water only.

Bag Weight

50 lbs. (22.7 kg)

Coverage (est.)*

1/16" coat troweled on Kal-KoteBase Plaster, 650-700 sq. yds. perton (145-160 sq. ft. per bag).

16

Veneer Plaster Accessories*Used in Both One-Coat and Two-Coat Systems

* Metal products are not manufactured by National Gypsum Company.

KAL-KORNER BEAD

Formed of galvanized steel to protectexterior corners with veneer plas-tering. Flange length 1-1/4".

EXPANDED VENEERCORNERBEAD

Used as an alternate to the Kal-Korner Bead for exterior corners.Has 1-1/4" flanges.

ARCH CORNERBEAD

Can be used straight for exteriorcorners or flanges, or may besnipped and bent to form arches.

VENEER J TRIM CASING BEAD

Used as a finished edge at doorand window jambs by slippingover edge of plaster base.

VENEER L TRIM CASING BEAD

Used as a finished edge at doorand window jambs.

E-Z STRIP® CONTROL JOINT

Designed for drywall or veneerplaster systems. A vinyl extrusionused as an expansion or controljoint for ceilings or partitions.

KAL-MESH TAPE

A coated non-adhesive fiberglasstape which is stapled to Kal-Koreto reinforce all joints and interiorangles.

1-1/2" DRYWALL FURRINGCHANNEL CLIP

Attaches screw furring channel to1-1/2" cold rolled steel channel.

.093 ZINC CONTROL JOINT

Designed as an expansion or con-trol joint for ceiling and partitionareas for both drywall or veneerplaster systems.

17

Three acceptable methods of treating Kal-Kore joints are:

Drywall Paper TapeTreatment Method

1. Trowel Kal-Kote Base Plaster,Uni-Kal or X-KALibur over joint linefilling the channel formed by thetapered edges of the Kal-Kore boardin an even fashion.

2. Center drywall paper tape overthe joint line and embed the tapeinto the soft plaster using a troweland level the joint. Tape the fulllength of the joint.

3. Allow the treated joints to setprior to general plaster application.

Sta-Smooth Paper TapeTreatment Method

1. Mix Sta-Smooth Compound perinstructions on package. Do notcontaminate the compound withother materials, dirty water or pre-vious mixes. Do not retemper.

2. Apply the Sta-SmoothCompound to the joint by hand ormachine tool. The drywall papertape must be centered over thejoint line and embedded into thesoft compound. Do not over-trowelto a slick surface. Leave the surfacerough to provide mechanical key-ing of the plaster.

3. Allow the treated joints to setand dry prior to general plastering.

frames, and other openings, unlesscontrol joints are created using E-ZStrip Control Joints.

4. Fasten Kal-Kore to framingmembers with face out, using theproper type and spacing of fasten-ers shown under types of fasteners.

5. Draw Kal-Kore tight to framing.Drive fasteners straight and dimplethe surface without breaking thepaper face.

Kal-Korner Bead Application

Install Kal-Korner Bead using appro-priate fasteners spaced 12" apart.

E-Z Strip Control JointApplication

Install E-Z Strip Control Joint at 30'max. spacing on walls and 50' max.spacing in either direction on ceilings.Apply the control joint with staplesspaced 6" along each side of theflanges.

Treatment of Kal-Kore Joints

Pre-treat all joints and fasteners inKal-Kote and Uni-Kal Plaster Systemswith Kal-Kote Base Plaster, Uni-Kal,X-KALibur or Sta-Smooth JointCompound.

Low humidity, high temperaturesand rapidly circulating air cancause cracking of plaster and jointbeading when Kal-Kore is appliedto metal framing. To minimize thisduring these conditions, joints maybe pre-treated using paper tape.

Veneer Plaster for Metal and Wood Framing1. Wood Studs or Joists. Woodmembers shall meet the minimumrequirements of local building codes.Framing shall not exceed spacingshown on page 14. Most partitionfire ratings require that Kal-Kore beapplied vertically.When such ratingsare not required, horizontal applica-tion may be used to minimize joints.For ceilings, application at rightangles to framing is preferred.

2. Metal Studs. Align floor andceiling tracks to assure plumb parti-tion. Secure track with appropriatefasteners at a maximum of 24" o.c.Position studs in track on specifiedcenters by rotating into place for afriction fit. Secure studs located adja-cent to door and window frames,partition intersections and corners byself-drilling sheet metal screwsthrough both flanges of studs andtracks or by use of screw stud clinch-ing tool.Apply Kal-Kore vertically formost fire ratings.When ratings arenot required, horizontal applicationmay be used to minimize joints.

3. Masonry Wall Furring withScrew Furring Channel. Attachfurring channel vertically spacednot to exceed spacing shown onpage 14. Fasten each channel with

concrete stub nails or appropriatefasteners through channel flangesinto the masonry or concrete.Fasteners shall be spaced on alternate flanges not over 24" o.c.Apply Kal-Kore vertically or horizontally in maximum lengths to minimize end joints.

4.Furred Ceilings with Bar Joists.Attach regular furring channel 16" o.c.to bar joists spaced up to 4' o.c.Resilient Furring Channel (wire-tiedonly) shall span a maximum of 24".Wire tie Furring Channel to joists oruse 1-1/2" Drywall Furring ChannelClip for 1-1/2" carrying channel.ApplyKal-Kore with paper bound edges atright angles to the furring channel.

Kal-Kore ApplicationNote: Application shall conform toASTM C 844.

1. Cut and position Kal-Kore accu-rately. Bring all joint edges togetherbut do not force into place. Positionall end joints over framing members.To avoid ridging, minimize gapsbetween adjacent panels.

2. Minimize the number of endjoints by using maximum practicallengths with proper positioning.

3. Stagger joints so that they occuron different framing members andwill not be directly opposite oneanother on partitions. Avoid joiningKal-Kore at corners of doors, window

Recommendations

Kal-Kore Board

Uni-Kal or X-KALibur Finish

Kal-Kore Board

Kal-Kote Base

Kal-Kote Smooth Finish

Kal-Kore Board

Kal-Kote Base

Kal-Kote Texture Finish

18

directly, or in previously preparedwater solution form to obtain themost uniform effect.

2. Never use gauging or mouldingplasters in place of commercialaccelerator since they can adverselyaffect working qualities.

Kal-Kote Application Over Kal-KoreBasecoat Over Kal-Kore

1. Tightly scratch material into previously treated joints and corner-beads, then immediately scratch-intightly over the wall and/or ceilingarea.

2. Double back over the area justtroweled with material from thesame batch bringing total thicknessup to 1/16" minimum.

3. When plaster has “taken up,”eliminate excessive trowel marksand fill all surface voids and imper-fections to obtain a reasonably uniform surface. Do not over-trowelto a slick surface. Roughen theunset basecoat plaster surface witha serrated darby or lightly wire raketo provide mechanical keying forthe finish plaster when necessary.

2. Add plaster and allow to soakfor about 1 minute or add plasteras mixer is turning, then mix untiluniformly wetted.

3. Add remaining water and mixsufficiently to obtain desired lump-free material fluidity.

Note:A. Mixing periods greater than 5minutes will not be required ifproper equipment and procedureare used.

B. Mix no more than two bags perbatch to avoid mixing too far inadvance of application.

C. Caution is advised against mixingmore than two successive batcheswithout thorough equipment clean-up to avoid undue set acceleration.

D. Avoid the practice of mixingpartial bags since this leads to difficulty in maintaining uniformmaterial qualities.

Job Setting Adjustment

1. Basecoat and Finish Plasters:Small amounts of commercialretarder or commercial gypsumtype accelerator may be cautiouslyused to adjust setting time whenextreme conditions demand. Whencommercial retarder or acceleratoris used, add to mixing water

Kal-Mesh Treatment Method

Do not use self-adhering mesh.

1. Center and secure Kal-Meshover all joints and interior angleswith 1/4" or 5/16" staples.

2. Position staples a maximum of24" apart as follows:

A. Joints: at alternate edges forthe run from end to end anddirectly opposite one another ateither end.

B. Angles: along ceiling edgeonly for wall-to-ceiling angles.Along one edge for wall-to-wallangles.

3. After the first staples are placedat the end of a joint or angle, pullunstapled Kal-Mesh as staplingproceeds to assure that it will lieflat against the Kal-Kore.

4. Pre-treat all joints and Kal-Beadswith Kal-Kote, Uni-Kal or X-KALiburPlaster. Tightly trowel over joint linein both directions to prevent voids,feathering to a maximum width ofabout 6".

5. Allow the treated joints to setprior to general plaster application.

PlasteringNote: Application shall conform toASTM C 843.

The same general job conditionsused in good conventional plasteringpractice should be maintained.However, because Veneer Plastercoats are thin, particular actionmust be taken to guard againstdryouts (primarily avoiding directexposure to concentrated sources of heat and drafts.)

Special attention should also begiven to temperature conditionsunder which the system is installed.Both “in-place” and applicationperformance of individual VeneerSystem components will be greatlyenhanced if all construction areasand materials are at a suitabletemperature equilibrium before,

during and after installations.During cold weather, maintain atemperature 55˚F (13˚C) to 70˚F(21˚C) before, during and afterinstallation of all system componentsuntil building is occupied.

Mixing

Equipment: Mixing should bedone with a high-speed mechanicalmixer. A paddle-type agitator fittedto a 500-600 RPM heavy duty,1/2" electric drill and a clean,smooth-sided drum of convenientsize are recommended for rapid,efficient mixing of all Kal-KotePlaster types.

Water Ratios: Use only clean,fresh water suitable for humanconsumption. Basecoat: 10-12 qts.per 80 lb. bag. Smooth Finish: 18-20qts. per 50 lb. bag. Texture Finish:11-12 qts. per 50 lb. bag. Uni-Kaland X-KALibur: 13-15 qts. per 50 lb. bag.

Procedure

1. Put all but 1 to 2 qts. of theproper water volume in a suitablemixing drum.

Note: Starting with an insufficientamount of mixing water will seriouslydegrade mixing and applicationperformance.

19

Smooth Finish Over Basecoat

1. Apply only over properly preparedKal-Kote basecoat plaster. Scratch-intightly, then double back withmaterial from the same batchimmediately to create a uniformcoat not exceeding 1/16" in averagethickness.

2. Remove trowel marks,“cat faces,”and other major surface imperfec-tions by “drawing-up” or “layingdown” the surface with light trowelpressure when plaster has stiffened.

Use water sparingly if needed, butdo not over-trowel or over-waterbecause this aggravates any normaltendency for blistering when workingover low suction bases. Such blistering will be eliminated by thefinal water-troweling operations.

3. Water-trowel to densify and polishthe surface to the desired degreewhen plaster has set, eliminatingany blistering if present. Never usea felt “blister brush” as a substitutefor water troweling!

4. Uni-Kal and X-KALibur Plastermay be substituted for Kal-KoteSmooth Finish.

Texture Finish Over Basecoat

1. Apply per (1) under SmoothFinish.

2. When plaster has stiffened, floatits surface to any desired finish.

Do not float the soft surface of plaster which has already set.

Up to equal parts of clean, gradedsilica sand may be added to Uni-Kal and X-KALibur to aid texturing.

Uni-Kal or X-KALiburApplication over Kal-Kore1. Tightly scratch material into previously treated joints and corner-beads, then immediately scratch-intightly over the wall and/or ceilingarea.

2. Double back over the area justtroweled with material from thesame batch bringing total thicknessup to 3/32" minimum.

3. Begin finish troweling at time of initial set, using water sparingly.Final troweling must be accom-plished before complete set takesplace, as evidenced by darkening of the surface.

Note: Uni-Kal or X-KALibur maybe applied to produce a texturedfinish.

A. When Uni-Kal or X-KALibur ismixed, add up to but not exceed-ing 50 lbs. of silica sand, texturinggrade, per 50 lb. bag of plaster.

B. The sanded Uni-Kal or X-KALiburmix should be scratched-in tightlyover the plastering base. Immediatelydouble back over the area justtroweled with material from thesame batch.

C. When plaster is well taken up,float to the desired texture finish.

Painting Plaster

Various job conditions such as suction differences, wet or onlypartially dry walls, and reactionsbetween paint and lime may cause unsatisfactory paint finishesparticularly on new construction.

Alkali-resistant primers specificallyformulated for use over new plas-ter will permit decorating with oilor latex type paints. Quality paintproducts should be used and manufacturers’ recommendationsfollowed. Finished plaster shouldbe painted or covered to concealpossible discoloration. The paintsystem should be suitable for use over plaster surfaces that contain lime.

It is essential that plaster be soundand completely dry before painting.Under good drying conditions,veneer plaster may be painted 48hours after application.

Veneer Plasters Directto Bond-CoatedMonolithic ConcreteDescription

The Kal-Kote System, consisting ofa basecoat plaster and a finishcoat plaster, Uni-Kal or X-KALiburmay be applied directly to mono-lithic concrete treated with a bond-ing agent.

Limitations

1. Surface to be plastered shall betreated with a bonding agentapplied according to manufacturer’sdirections. The performance of thissystem is the sole responsibility ofthe bonding agent manufacturer.

2. Concrete should be aged atleast one month prior to plastering.

3. Kal-Kote Smooth or TextureFinishes are not designed for directapplication to concrete, but mustfirst have Kal-Kote Base Plasterapplied to fill and level surface.

4. Do not apply system to the interior side of exterior walls belowgrade. To use above grade thesewalls shall be kept dry and shallhave been properly waterproofedon the exterior side to preventwater penetration.

Application Procedures

Note: Application shall conform toASTM C 843.

Kal-Kote BaseApplication OverBonding Agent1. First straighten any major sur-face irregularities, such as holes,ridges, wavy sections, etc. Scratchplaster in tightly by trowel and fillout to any adjacent level area.

2. After the straightening materialhas set, trowel in a tight scratchcoat over the entire area to beplastered; then immediately doubleback with material from the samebatch to minimum thickness of1/16" or as required to achieve alevel surface. Use a rod or featheredge if needed.

3. When plaster has “taken up”,eliminate excessive trowel marksand fill all surface voids and imper-fections to obtain a reasonably uniform surface. Do not trowel to aslick surface. Roughen the unsetbasecoat plaster surface with a serrated darby or lightly wire raketo provide mechanical keying forthe finish plaster when necessary.

Smooth or Textured Finishes

Apply finishes to the Kal-KotePlaster as outlined under the regularKal-Kote System as described onpage 18.

Uni-Kal or X-KALiburApplication overBonding Agent1. First straighten any major surfaceirregularities such as holes, ridges,wavy sections, etc. Scratch plasterin tightly by trowel and fill out toany adjacent level area.

2. Allow the straightening materialto set.

3. Tightly scratch material in overthe wall and/or ceiling area. Thisapplication should be about 1/16"thick. Double back over the areajust troweled with material fromthe same batch bringing totalthickness up to 3/32" minimum.

4. Begin finish troweling at time ofinitial set, using water sparingly.Final troweling must be accom-plished before complete set takesplace, as evidenced by darkening of the surface.

Veneer Plasters Direct to Unit Masonry Description

The Kal-Kote System, consisting ofa basecoat plaster and a finishcoat plaster, Uni-Kal or X-KALibur,and the one-coat system, may beapplied direct to masonry surfacesproviding the following recommen-dations are followed.

20

Recommendations

1. Surface must be free from dirt,grease, oil, mold, parting agents, orany material which will preventplaster adhesion.

2. When erecting masonry, strikejoints flush. If masonry hasrecessed joints, fill joints flush tomasonry surface with basecoatplaster, Uni-Kal or X-KALibur andallow to set.

Exterior Corners

Install cornerbead with adhesive atleast 4 and preferably 16 hoursbefore plastering.Apply a continuousbead of adhesive approximately 1/4"x 1/4" along the inside of bothcornerbead flanges. Press the beadfirmly over the corner so that adhesive is in continuous contactwith masonry surface. Align beadand allow to stand undisturbed at least 4 hours.

Kal-Kote Application

Note: Application shall conform toASTM C 843.

Proceed with the full field of the wallby scratching-in tightly, then doubleback immediately with material fromthe same batch to a minimum thick-ness of 1/16" over the block surface,or as required to level.

Kal-Kote Finishes should be kept asthin as possible and applied asdescribed on pages 18 and 19.

Uni-Kal or X-KALiburApplication

Caution: Since Uni-Kal or X-KALiburis a one-coat material system,exercise care in leveling the wall tocompensate for the uneven suction.

Proceed with full field of the wallby scratching-in tightly, then doubleback immediately with same batchof material to a minimum thicknessof 3/32" over the block surface.

Veneer SystemsApplied to Masonrywith Z FurringChannel SystemDescription

This system consists of a Z FurringChannel, rigid insulation and thecomponents of the Kal-Kote andUni-Kal or X-KALibur VeneerPlaster Systems. The Z FurringChannel is manufactured from galvanized steel (.0179" min. basesteel) and is produced with webdepths of 1", 1-1/2" and 2". Thefurring channel which is applied toa masonry wall holds the insulationin place and the wide flange servesas framing for the application ofthe Kal-Kore plastering base.

Limitations

1. Since the interior wall surfacewill take the general configurationof the masonry wall, it may be nec-essary when applying the systemto unit masonry to use portlandcement plaster to bring the wall toa plane surface.

2. This system is mainly for newmasonry construction. On well-curedconcrete or masonry, it may be difficult to properly drive fasteners.

3. Power-driven fasteners shall be used only for attachment tomonolithic concrete surfaces.

4. Kal-Kore should be applied within24 hours of foam application.

Application Procedures

1. Begin application of Z Furringmembers by positioning first channelvertically at a corner, locating it onthe wall adjacent to the wall beinginsulated first.

The insulation thickness determinesthe distance of Z Furring web fromwall being insulated. At the appro-priate distance, with wide flangepointing toward applicator, secure ZChannel with appropriate fasteners,spaced 24" o.c. driven throughshort flange. (Note: Power-drivenfasteners are not recommended foruse with masonry block.)

Install 24" wide floor-to-ceilinginsulation panel, pressed snuglyagainst web of first Z. Install next Zwith the wide flange overlappingthe edge of the first insulationpanel. Fasten Z to wall throughnarrow flange. Continue in thismanner with Z Furring member24" o.c. to end of wall. Locate lastZ so that web is located a distanceequal to insulation thickness fromadjoining wall. Cut last insulationpanel to fit remaining space.

At exterior corner, attach the Zthrough its wide flange with narrowflange extending beyond the corner.Begin with a narrow strip of floor-to-ceiling insulation, wider thaninsulation thickness, but notexceeding 3". Continue applicationof furring and insulation progres-sively as described above.

At windows, doors and trim areas,use wood nailers, nominal 2" widex insulation thickness plus 1/32".Use the nailers also at wall-floorangles to support trim and providebacking for base.

2. Apply Kal-Kore to the flanges ofZ Channel with 1" Type S screwsspaced 12" o.c. Normally, verticalapplication of Kal-Kore is recom-mended; however, for installations8' or less in height, horizontalapplication may be preferred sincethe number of joints would bereduced.

3. Apply Kal-Mesh and Kal-KornerBead according to proceduresdescribed on pages 16 and 17.

4. Mix and trowel on Kal-KoteBase and Finish Plaster or Uni-KalPlaster as described on pages 18and 19.

Condition

IN-PLACE CONDITIONS

Joint Cracking

Random Or Map Cracking

Mud Cracking(Craze, Shrinkage, Alligator)

Dryout

Nail Pops

Probable Cause

1. Wrong type of reinforcing meshor tape was used.

2. No reinforcing mesh was used, orimproperly positioned over joint.

3. Joint not pretreated prior togeneral plastering.

4. Rapid drying conditions.5. Expansion/contraction.6. Thermal shock.7. Structural movement.

Concentrated stresses caused bydifferential shrinkage or expansionbetween plaster and substrate orbetween individual plaster coats –thermal shock.

Rapid drying or too thin plasterapplication.

1. Rapid drying conditions.2. Thin plaster application.3. Excessive job addition or retarder.

1. Nail or screw heads puncturing face paper.

2. Nails or screws not securely driven, loose or improper type.

3. Framing members out of align-ment or lumber shrinkage.

4. Plaster base not applied tightagainst framing members.

Preventive Action

1–3. Use proper type of mesh andrecommended joint installationprocedures. – DO NOT USE SELF-STICK (PRESSURE SENSITIVE) MESH.

4. Avoid hot, low humidity air, highdraft exposure.

5. Install control joints as required.6. Avoid extreme and rapid tempera-

ture differentials (thermal shock).7. Avoid jointing plaster base at

corners of openings, stagger jointson opposite side of partition.

Maintain minimum 55°F (18°C)conditions prior to, during and afterplastering.

Avoid rapid drying conditions, applyplaster at recommended thickness.

1. Avoid rapid drying conditions.2. Apply plaster at recommended

thickness.3. Avoid job additions of retarder.

Follow recommended veneer plasterbase application procedures.

Corrective Action

Large Cracks: Scrape crack and apply drywall tape and settingtype joint compound.Small Cracks: Fill and feather out area with ready mixed jointcompound.

Fill and feather area with readymixed joint compound.

Apply ready mixed joint compound.

General or large area “dry-outs”–remove plaster; vacuum or wipedown surface, apply bonding agentand replaster.Small areas – spray surface withwater or alum solution to set plas-ter. Repair area with ready mixedjoint compound for an acceptablesurface.

Remove plaster around fastenerand seat it properly and drive anadditional fastener about 1-1/2"away from the popped fastener.Patch with plaster or ready mixedjoint compound.

Conditions/Causes/Prevention/CorrectionVeneer plaster problems are gener-ally related to job conditions orabuses and marginal or improperplastering techniques or practicesand infrequently to a product qualitydeficiency.

The prime job conditions initiatingproblems are:

� Improper material storage andhandling.

� Poor or improper plasteringpractices and techniques.

� Adverse or extreme environmentalconditions.

� Improper or deficient substratefor accepting plasters.

Some of the problems associatedwith veneer plaster constructionhave the same cause - prevention –correction characteristics as drywall.These main common conditions are:

� Gypsum base application deficiencies.

� Structural and framing irregularities and deficiencies.

� Fastening deficiencies.

� Structural movement.

Attention to good plastering practices and procedures will minimize or eliminate job siteproblems and call-backs.

21

Veneer Plaster Problems and Solutions

22

Condition

IN-PLACE CONDITIONS (cont.)

Joint Ridging Or BeadingMost commonly occurring when steel studs (24" on center) are used and rapid drying conditions exist

Rusting/Staining Of Finish

Photographing Or Ghosting Of Joint Line

Joint Shadowing Caused ByDepression Or Ridging

Bond FailureCause(s) of bond failure is perhaps the most difficult con-dition to diagnose because ofthe great number of factors whichcan influence plaster bonding

Probable Cause

1. Large gaps between adjacentplaster base boards.

2. Improper/insufficient number/location of fasteners.

3. Gypsum base board edges damaged.4. Wrong type or no reinforcing

mesh used.5. Joints not pre-treated prior to

general plastering.6. Rapid drying conditions.

Use of improper fasteners or metaltrim.

1. Differential in base plaster suctionbetween joint and field.

2. Too thin a coat of base plasteroverall, resulting in a very thincovering over mesh.

3. Partially dry base plaster, moisturecontent differential greaterbetween joint and field.

Gypsum veneer base gapped causing a depression or ridge atthe joint line.

Product Related Causes:1. Use of pressure sensitive mesh –

reduces plaster substrate contact.2. “Setting” or “drying” type joint

compounds used to treat joints.Job Condition Causes:1. “Dry-out” or “partial dry-out” –

plaster loses water prior to com-plete setting or hydration.

2. Using plaster which has beenexposed to the atmosphere,open bags or improper storage.

3. Freezing of plaster before settinghas occurred.

4. Application of plaster over froston substrate.

5. Excessively rapid thermal changes.6. Excessive thermal differences

between the face and back ofthe plaster base.

Application Practice Causes:1. Application of lime containing plas-

ter over light faded veneer base.2. Use of retempered plaster,

remixing with additional waterplaster which has “bucked-up”(stiffened) or started to set to render it workable again.

3. Excessive delay in applying plasterafter mixing – application nearor into the initial setting action.

Preventive Action

1–3. Apply undamaged plasterbase board according to recommended procedures usingproper fastening.

4/5. Use recommended reinforcing mesh or paper tapeand pretreat joints prior to gen-eral plastering.

6. Avoid rapid drying conditions.

Use only recommended fastenersand trim.

Apply basecoat plaster to full thickness, following recommendedprocedures.

Follow recommended veneer baseand plaster application procedures.

The best advice for preventingveneer plaster problems is to strictlyfollow the manufacturer’s recom-mendations and adhere to properplastering practices.

Corrective Action

Sand the ridge or bead and applyready mixed compound and featherout areas.

Prime affected area with a primer/sealer and redecorate.

Prime affected area with a primer/sealer and redecorate.

Fill depression with joint compound orsand ridges flush with field, skim coatwith joint compound and redecorate.

Remove all loose or marginallybonded plaster, brush the surfacethoroughly to remove dust (vacu-uming is recommended), apply aquality bonding agent per manu-facturer’s recommendations andreplaster.

23

Condition

IN-PLACE CONDITIONS (cont.)

Bond Failure (cont.)

Hard (Set) Lumps In Package

Set Time Variable Within The Same Job Mixed Batch

Set Time Variable From Batch To Batch

Slow Set Plaster

Probable Cause

4. Excessive use of retarder to slowsetting, so partial dry-out occurs.

5. Adulteration of the plaster on thejob site by addition of substancesother than clean graded silicasand or excessive use of sand.

6. Application of plaster overimproper substrate.

7. Application of plaster over contaminated substrate, dust,dirt, oil, soot, etc.

8. Application of plaster over substrate with excessively highsuction – too high absorptivity.

9. Application of plaster over sub-strate with inadequate absorp-tivity – too low suction.

10. “Laying-on” or “buttering-on”plaster without adequate trowelpressure to provide mechanicalkeying to the substrate.

11. Inadequate or insufficient fin-ish troweling.

12. Basecoat plaster troweled toosmooth – reduces mechanicalkeying of finish to the base plaster.

13. Finish plaster applied over base-coat plaster too thick,and not tightlytroweled into the base plaster.

14. One coat finish applied too thin.

Plaster bags became wet during transit or storage.

1. Improper mixing equipment.2. Insufficient water used at the

start of mixing.3. Insufficient mixing time.

1. Dirty equipment2. No or improper equipment

clean-out procedures.3. Partial bag mixed.

1. Temperature below 40°F (4°C)or in excess of 100°F (38°C).

2. Job addition of retarder.3. Use of old, improperly stored

plaster or plaster from open bagswhich have been exposed to air.

4. Partial bag mixed.

Preventive Action

The best advice for preventingveneer plaster problems is to strictlyfollow the manufacturer’s recom-mendations and adhere to proper plastering practices.

Protect plaster from water during transit and storage.

1. Use recommended mixing equipment.

2. Add all but about 1 quart of therecommended amount of waterto the mixer at start.

3. Mix to a uniform fluidity; mixingtime should not exceed 5 minutes.

1. Use only clean equipment.2. Follow recommended equip-

ment clean-out procedures.3. Use only full bags.

1. Avoid extremes of air, plasterand mix water temperature.

2. Avoid job addition of retarder.3. Use only properly stored plaster

from unopened bags, less thana year old.

4. Use only full bags.

Corrective Action

Remove all loose or marginallybonded plaster, brush the surfacethoroughly to remove dust (vacu-uming is recommended), apply aquality bonding agent per manu-facturer’s recommendations andreplaster.

1. Screen out hard lumps beforemixing.

2. Discard the plaster.

See Prevention.

See Prevention.

1/2. During cold weather maintaintemperature between 55° and70°F before, during and afterplastering. Avoid job additions ofretarder. Cautiously use accelera-tor to speed up setting action.

3. Replace material.4. Use only full bags.

PLASTER APPLICATION CONDITIONS

24

Condition

Quick Set

Spreading Qualities Vary Within Batch

Spreading Qualities Vary From Batch To Batch

Smooth Or Texture FinishDesired, Not Obtained

Blistering Of Smooth FinishA common condition, especiallyover “green” basecoat plaster,less over gypsum veneer base

Fuzzing Or Ragging OfSmooth Finish Surface

Probable Cause

1. Dirty equipment.2. Excessive mixing.3. Contaminated mixing water.4. Plaster has become wet or

contaminated prior to mixing.5. Excessive use of accelerator.6. Excessively low air/plaster mix,

water temperatures below 40°F(4°C).

7. Partial bag mixed.

1. Improper mixing equipment/mixing action.

2. Insufficient water used at start ofmixing.

3. Insufficient mixing time.4. Aggregate separation.

1. Inconsistent mixing.2. Using part or open bags exposed

to air.3. Old or improperly stored plaster.4. Variable aggregate.

1. Surface of unset plaster beingworked at wrong time, too stiffor too soft.

2. Suction of substrate too high ortoo low.

3. Surface of plaster being workedafter plaster has set.

4. Intermixing material from differentmanufacturers.

1. Application of water onto theplaster surface with trowelingbefore sufficient stiffening(“take-up”) has occurred.

2. Aggravated by cold plasteringsurfaces.

1. Finish plaster surface lacks sufficient water for adequatetrowel lubrication or slip during“draw-up” operation.

2. Job-gauged finish componentsnot uniformly blended, causinglocalized dry spots due touneven water retention.

3. Excessive trowel pressure, trowelat wrong angle to the surface ortiming wrong for troweling.

Preventive Action

1. Follow recommended clean-outprocedures.

2. Do not exceed 5 minutes mixingtime.

3. Use only potable water.4. Use only properly stored, uncon-

taminated plaster.5. Maintain construction areas and

materials above 55˚F prior to,during and after plastering.

6. Avoid job additions of accelerator.7. Use only full bag.

Use recommended mixing equip-ment, water ratio and procedure.

1. Follow recommended mixingprocedures.

2/3. Use only full, unopened bags,which have been properly stored.

4. Replace aggregate and/or plaster.

1. Adjust finishing sequence tomeet plaster condition.

2. Gypsum Base: Adjust plasterworking time sequence to com-pensate for high or low suction.Basecoat Plaster: Apply finishover “green” moderately drybasecoat or dampen dry basecoat.

3. Follow recommended smooth ortexturing procedures.

4. Use only materials from singleproducer to ensure compatibility.

1. Reduce trowel pressure during“double-back” and “draw-up”operation. Use water sparinglyand only after adequate plaster“take-up” has developed or ini-tial setting action has occurred.

2. Maintain recommended workingarea temperature.

1. Wet trowel or sparingly applywater on plaster surface during“draw-up”.Avoid starting “draw-up” too long after “take-up”.

2. Be sure job-gauged finish components are uniformly andthoroughly blended.

3. Decrease trowel angle to surface,ease up on trowel pressure orstart troweling sequence sooner.

Corrective Action

1–5. Follow good recommendedplastering practices.

6. Cautiously use retarder to slowset time.

7. Use only full bag.

See Prevention.

See Prevention.

See Prevention.

Eliminate blisters with strong trowel pressure during final watertroweling operation, when plasteris firm and/or setting action inprogress.

See Prevention.

PLASTER APPLICATION CONDITIONS (cont.)

25

Condition

Peeling And Tearing Of SmoothFinish During Application

DECORATING PROBLEMS

Paint Peeling/BlistersUse only quality paintsspecifically recommended by the paint manufacturer for application over lime (alkaline) containing plasters

Joint Shadowing

Paint “Stringing” or “Roping”During Roll Application

Probable Cause

1. “Double-back” coat of finishtroweled over “scratch” coatwhich has stiffened excessivelyor set.

2. Trowel pressure during “draw-up” too strong for stiffness andthickness of finish.

1. Plaster not completely dry.2. Wrong type of paint used.3. Plaster surface chalky.4. Plaster surface contaminated,

grease, soot.5. Plaster became wet after

decoration was completed.

Depression or ridge at the jointline.

1. Wrong type of paint.2. Solids content of paint too high.3. Fast drying conditions.4. Plaster surface dusty.

Preventive Action

1. “Scratch” and “double-back”with finish from the same batch,minimizing time between coats.

2. Use only light, even trowel pressure when “drawing-up”.

1. Allow sufficient drying timebefore painting; consideration toenvironmental conditions isimperative.

2. Use only paint specifically rec-ommended by the paint manu-facturer for use over new orfreshly plastered surfaces.

3. Finish plaster per recommendedpractices, leave plaster surfaceunder trowel, do not brush finish.

4. Examine plaster surface for signsof contamination prior to painting.

5. Make sure areas are weather tightbefore plastering and printing.

See “Joint Shadowing Caused ByDepression Or Ridging.”

1. Use proper type of paint forplaster surfaces.

2. Dilute paint per manufacturer’srecommendations.

3. Reduce drying conditions.4. Make sure plaster is dust free.

Corrective Action

See Prevention.

1/2. Remove all peeling/blisteringpaint, allow sufficient dryingtime. Prime and redecorate.

3. Remove all peeling paint,and brush surface to removechalkiness. Apply primer recom-mended by paint manufacturerfor chalky plaster surfaces.

See “Joint Shadowing Caused ByDepression Or Ridging.”

1. Stop painting.2. Check preventative measures

and make necessary corrections.3. Allow painted area to dry and

repair by either sanding theaffected area or skimming withjoint compound to a smoothsurface and repaint.

4. Brush the surface thoroughly to remove dust (vacuuming isrecommended).

Painting PlasterVarious job conditions such as suction differences, wet or only partially drywalls, and reactions between paint and lime may cause unsatisfactorypaint finishes particularly on new construction.

Alkali-resistant primers specifically formulated for use over new plaster will permit decorating with oil or latex type paints. Quality paint productsshould be used and manufacturers’ recommendations followed. Finishedplaster should be painted or covered to conceal possible discoloration.The paint system should be suitable for use over plaster surfaces that contain lime.

It is essential that plaster be sound and completely dry before painting.Under good drying conditions, veneer plaster may be painted 48 hours after application.

PLASTER APPLICATION CONDITIONS (cont.)

26

Accelerator . . . . . . . . . . . . . . . . . . . .A substance used to shorten or speed up the setting action (time) of the plaster.

Admixture . . . . . . . . . . . . . . . . . . . .A substance other than water, or aggregate added to the plaster to alter its properties.

Aggregate . . . . . . . . . . . . . . . . . . . .An inert material used as a filler or texturing aid.

Anhydrite . . . . . . . . . . . . . . . . . . . . .An anhydrous form of gypsum.

Basecoat . . . . . . . . . . . . . . . . . . . . . .A plaster coat applied over a substrate prior to application of the finish coat.

Blistering . . . . . . . . . . . . . . . . . . . . .Bulging or separation of the wet finish plaster coat away from the base.

Bond . . . . . . . . . . . . . . . . . . . . . . . . .Adhesion between plaster coats or between plaster and substrate produced by mechanical and chemical properties of the plaster, or intermediate bonding agents applied prior to plastering.

Bonding Agent . . . . . . . . . . . . . . . .An adhesive substance applied to a substrate to provide a medium for plaster bond.

Brown Out . . . . . . . . . . . . . . . . . . . .A darkening of the exposed plaster surface indicating setting action is complete.

Buck-Up . . . . . . . . . . . . . . . . . . . . . . .A premature stiffening of plaster mortar shortly after mixing. Usually indicates a plaster deficiency or an adverse reaction to a job addition of aggregate.

Calcine . . . . . . . . . . . . . . . . . . . . . . . .To drive off water of crystallization by heating.

Calcined Gypsum . . . . . . . . . . . . . .Gypsum with 1-1/2 molecules of combined water removed – also called plaster, stucco, hemihydrate, semihydrate.

Cat Face . . . . . . . . . . . . . . . . . . . . . .A blemish or rough depression in the finish coat plaster.

Chemical Bond . . . . . . . . . . . . . . . . .Bond produced by the formation and subsequent interlocking of gypsum crystals during the setting process.

Coat . . . . . . . . . . . . . . . . . . . . . . . . . .A thickness, covering, or layer of plaster applied in a single operation.

Consistency . . . . . . . . . . . . . . . . . . .An amount of water required to bring a unit weight of dry plaster to a workable fluidity.

Craze Cracks . . . . . . . . . . . . . . . . . . .Fine random fissures or cracks in the plaster surface caused by plaster shrinkage due to loss of water before setting.

Cure . . . . . . . . . . . . . . . . . . . . . . . . . .The state of or conditions conducive to complete hydration of the plaster.

Dolomite . . . . . . . . . . . . . . . . . . . . . .A type of lime or limestone containing calcium with up to 50% magnesium as the hydroxide or carbonate.

Double-Up . . . . . . . . . . . . . . . . . . . .Plaster placement characterized by application of material from the same mixed batch in successive operations without setting or drying allowed between coats – double-back, laid-off, or two-coat work.

Draw-Up . . . . . . . . . . . . . . . . . . . . . .The troweling process after the applied finish plaster has “taken up”, whereby surface irregularities are filled and leveled with or without the use of fresh plaster on the tools.

Dry-Out . . . . . . . . . . . . . . . . . . . . . . .A condition where some or all of the water necessary for plaster hydration is lost by evaporation or excessive suction.

Efflorescence . . . . . . . . . . . . . . . . . .A white, fleecy surface deposit of salts.

Fat . . . . . . . . . . . . . . . . . . . . . . . . . . .Soft usable plaster accumulated on trowel during finishing operation, often used to fill in small imperfections.

Finish Coat . . . . . . . . . . . . . . . . . . . .The last layer of plaster applied – smooth or texture.

Finishing Brushes . . . . . . . . . . . . . .Brushes used to dash water onto the surface of finish plaster during smooth troweling.

Float . . . . . . . . . . . . . . . . . . . . . . . . . .Tool or procedure used to straighten and level the finish coat surface to correct surface irregularities produced by other tools and to impart a distinctive surface texture.

Float Finish . . . . . . . . . . . . . . . . . . . .A finish coat texture derived primarily from aggregate particles in the plaster.

Gauging . . . . . . . . . . . . . . . . . . . . . .Gypsum plaster added to lime putty to provide and control set.

Green . . . . . . . . . . . . . . . . . . . . . . . . .Newly applied plaster that has set but not completely dried out.

Hawk . . . . . . . . . . . . . . . . . . . . . . . . .Tool used by plasterers to hold and carry plaster mortar, in conjunction with troweling.

Hemihydrate . . . . . . . . . . . . . . . . . .Calcined gypsum.

High Calcium Lime . . . . . . . . . . . . .The oxide or hydroxide derived from limestone, which is principally calcium carbonate.The product contains less than 5% magnesium oxide or hydroxide.

Hydrate . . . . . . . . . . . . . . . . . . . . . . .Term used to denote hydrated lime.

Hydrated Lime . . . . . . . . . . . . . . . . .Quicklime (oxide) which has been hydrated to yield the hydroxide, a dry powder.

Joining . . . . . . . . . . . . . . . . . . . . . . . .The juncture of two separate plaster applications on a common surface.

Landplaster . . . . . . . . . . . . . . . . . . .Ground natural gypsum.

Lay Down . . . . . . . . . . . . . . . . . . . . .The troweling process after the applied finish plaster has “taken up”, whereby surface irregularities are filled and leveled with or without the use of fresh plaster on the tools.

Glossary of Terms

27

Lean Mixture . . . . . . . . . . . . . . . . . .High aggregate to plaster ratio; often exhibits poor working qualities.

Light Weight Aggregate . . . . . . . .Expanded perlite or vermiculite.

Lime . . . . . . . . . . . . . . . . . . . . . . . . . .Oxides or hydroxides of calcium or calcium and magnesium.

Lime Putty . . . . . . . . . . . . . . . . . . . .A thick paste obtained by “slaking” quicklime or soaking and mixing hydrated lime with a minimum of water.

Mechanical Bond . . . . . . . . . . . . . .Physical keying of plaster to substrate.

Mill Mixed . . . . . . . . . . . . . . . . . . . .Plasters requiring only water addition on the job site.

Mortar . . . . . . . . . . . . . . . . . . . . . . . .A material used in plastic state which can be troweled and hardens after placement.

Mud Cracks . . . . . . . . . . . . . . . . . . . .Fine random cracks in the plaster surface caused by plaster shrinkage due to loss of water (dry-out) before setting.

Perlite . . . . . . . . . . . . . . . . . . . . . . . .A siliceous volcanic glass – expanded by heating into a lightweight plaster aggregate.

Plaster Bond . . . . . . . . . . . . . . . . . .Adhesion between plaster coats or between plaster and a plaster substrate produced by a mechanical and chemical interlocking of plaster with the substrate.

Purity . . . . . . . . . . . . . . . . . . . . . . . . .The percentage of calcium sulfate dihydrate contained in a fully hydrated gypsum plaster.

Relative Humidity . . . . . . . . . . . . . .The ratio of the amount of water vapor actually present in the air to the greatest amount possible at the same temperature, expressed as a percentage.

Retarder . . . . . . . . . . . . . . . . . . . . . .A material added to plaster which will lengthen the setting time.

Retemper . . . . . . . . . . . . . . . . . . . . .To mix additional water with plaster which has begun to stiffen or set so as to render it workable again.

Sand . . . . . . . . . . . . . . . . . . . . . . . . . .A washed and size-graded, granular natural material (aggregate) added to veneer plasters to aid float texturing of the plaster.

Scratch And Double . . . . . . . . . . . .Plaster application characterized by a tight application of plaster against the substrate and immediately followed by a second application of plaster from the same batch of mixed plaster.

Setting Time . . . . . . . . . . . . . . . . . . .The elapsed time after mixing with water for the plaster to harden or hydrate.

Sweeten . . . . . . . . . . . . . . . . . . . . . .The troweling process after the applied finish plaster has “taken up”, whereby surface irregularities are filled and leveled with or without the use of fresh plaster on the tools.

Take-Up . . . . . . . . . . . . . . . . . . . . . . .A normal stiffening of the applied plaster resulting from the removal of water from the plaster by absorption (suction) into the substrate.

Trowel Finish . . . . . . . . . . . . . . . . . .Denotes a smooth finish surface produced by troweling.

Veneer Plaster . . . . . . . . . . . . . . . . .A specially manufactured gypsum plaster which provides strength, hardness and abrasion resistance and is capable of thin application over designated substances.

Veneer Plaster Base . . . . . . . . . . . .A gypsum board with special paper facing designed to provide water absorption for rapid veneer plaster application and finishing.

Workability . . . . . . . . . . . . . . . . . . . .The ease and speed with which plaster mortar can be applied and finished.

110753 Rev. 5/07

Technical Data

Corporate Headquarters

National Gypsum Company2001 Rexford RoadCharlotte, NC 28211

Phone: (704) 365-7300Web: nationalgypsum.com

nationalgypsum.com/espanol

Technical Information

Phone: (800) NATIONAL(800) 628-4662

Fax: (800) FAX-NGC1(800) 329-6421

� Atlantic AreaPhone: (800) 237-9167Fax: (877) 252-0430

� Central AreaPhone: (800) 252-1065Fax: (866) 232-0440

� Gulf AreaPhone: (800) 343-4893Fax: (866) 482-8940

� Midwest AreaPhone: (800) 323-1447Fax: (866) 692-8590

� Northeast AreaPhone: (800) 253-3161Fax: (866) 632-1480

� Southeast AreaPhone: (800) 548-9394Fax: (866) 732-1990

� Southwest AreaPhone: (800) 548-9396Fax: (866) 792-7520

� Western AreaPhone: (800) 824-4227Fax: (800) 438-6266

National AccountsPhone: (800) 440-1230Fax: (866) 622-3590

Manufactured HousingPhone: (800) 455-3185Fax: (800) 639-1714

LIMITED WARRANTY AND REMEDIESProducts manufactured and sold byNational Gypsum are warranted by NationalGypsum to its customers to be free fromdefects in materials and workmanship atthe time of shipment. THIS EXPRESS WARRANTY IS THE ONLY WARRANTYAPPLICABLE TO SUCH PRODUCTS, AND ISIN LIEU OF AND EXCLUDES ALL OTHEREXPRESS ORAL OR WRITTEN WARRANTIESAND ALL IMPLIED WARRANTIES, INCLUDINGBUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY ANDFITNESS FOR A PARTICULAR PURPOSE.National Gypsum will not be liable for anyincidental, indirect or consequential losses,damages or expenses. The customer’sexclusive remedy for any type of claim oraction for defective products will be limitedto the replacement of the products (in theform originally shipped) or, at NationalGypsum’s option, to a payment or creditnot greater than the original purchase price of the products.National Gypsum will not be liable forproducts claimed to be defective where thedefect resulted from causes not withinNational Gypsum’s control, or which aroseor occurred after shipment, including butnot limited to accidents, misuse, mishandling,improper installation, contamination oradulteration by other materials or goods, or abnormal conditions of temperature,moisture, dirt or corrosive matter.Any claim that products sold by NationalGypsum were defective or otherwise didnot conform to the contract of sale iswaived unless the customer submits it inwriting to National Gypsum within thirty(30) days from the date the customer discovered or should have discovered thedefect or nonconformance. No legal actionor proceeding complaining of goods soldby National Gypsum may be brought by thecustomer more than one year after thedate the customer discovered or shouldhave discovered the defect or problem ofwhich it complains.

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