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ContentsIntroduction.................................................................................................................4Substrates Menu..........................................................................................................4
Softwood Timbers...............................................................................................5Hardwood Timbers..............................................................................................5Particle Board (Chipboard)..................................................................................6Hardwood (Sheeting)..........................................................................................6Craftwood / MDF (Medium Density Fibreboard)...................................................7Plywood...............................................................................................................7Gyprock Plasterboard..........................................................................................8Fibrous Plaster / Plaster Glass.............................................................................8Hard Plaster / Gypsum Plaster.............................................................................9Fibre Cement (Hardi Sheet)................................................................................9Masonry............................................................................................................10Ferrous Metals..................................................................................................10Non-Ferrous Metals...........................................................................................11Plastics (PVC)....................................................................................................11Expanded Polystyrene.......................................................................................12Vermiculite........................................................................................................12Glass Glazed Tiles.............................................................................................13
End of Substrates......................................................................................................13Substrate Defects Menu............................................................................................13
Lack of Adhesion...............................................................................................14Bleeding Stains.................................................................................................14Dampness.........................................................................................................14Acidic Substrates..............................................................................................15Alkaline Substrates...........................................................................................15Efflorescence.....................................................................................................16Corrosive Substrates (Metal).............................................................................16Mould & Mildew.................................................................................................16Dry Rot..............................................................................................................17Wet Rot.............................................................................................................17
Conclusion.................................................................................................................18Credits - Funding.......................................................................................................18Credits - Images........................................................................................................18About the National VET E-learning Strategy..............................................................18
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IntroductionMain Painter: Wood, plaster, cement, plastic… all of these different substrates - they’re driving me crazy!Helper Painter: It’s easy! Let’s take a look.Main Painter: There are so many different types of surfaces we paint on. Can't we just paint them all the same?Helper Painter: But these surfaces differ greatly in composition and characteristic. You will need to know how to tell them apart, what kind of prep is required, and select a suitable coating.Main Painter: I wish there was only one type of surface we painters have to paint.Helper Painter: I know what you mean. But how boring would that be? It's not that hard - let's go through them one by one.
Substrates Menu• Softwood Timbers• Hardwood Timbers• Particle Board (Chipboard)• Hardwood (Sheeting)• Craftwood / MDF (Medium Density Fibreboard)• Plywood• Gyprock Plasterboard• Fibrous Plaster / Plaster Glass• Hard Plaster / Gypsum Plaster• Fibre Cement (Hardi Sheet)• Masonry• Ferrous Metals• Non-Ferrous Metals• Plastics (PVC)• Expanded Polystyrene• Vermiculite
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• Glass Glazed Tiles
Softwood TimbersUsed for construction, and include Pine, Oregon, Cedar, etc.
Properties: • Porous, absorbent, soft, strong and straight.
Defects: • Resinous knots.
Preparation: • Sand and dust.
First coat:• Oil or water based primers.• Oil or water based clear coatings.
Example image:• Cedar
Hardwood TimbersUsed for construction and decorative purposes, panelling and veneering. Includes oak, ash, beech, jarrah, karri, teak, etc.
Properties:• Porous, absorbent, hard, strong and durable.
Defects:• May contain sap if still ‘green’ (damp).
Preparation:• Sand and dust.
First coat:• Oil or water based primers.• Oil or water based clear coatings.
Example image:• Jarrah
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Particle Board (Chipboard)Wood chips and resin firmly compressed at a high temperature. Used mainly for furniture and shelving.
Properties:• Rigid, dense, even textured, water-resistant chipboard used for flooring.
Defects:• Non-resistant chipboard will swell when wet.
Preparation:• Remove dust.
First coat:• Water based primer.• Water based clear coating.
Example image:• Chipwood
Hardwood (Sheeting)Made from wood pulp, wood fibres and resin firmly compressed at a high temperature (e.g. masonite). Used as a lining for walls, ceilings and panel doors.
Properties:• Porous, absorbent, hard, strong and durable.
Defects:• Very smooth.
Preparation:• Remove dust.
First coat:• Oil based primer or sealer.• Oil based clear coating.
Example image:• Masonite
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Craftwood / MDF (Medium Density Fibreboard)Fibreboard used for shelving, doors, furniture and mouldings. Has replaced chipboard in many situations.
Properties:• Strong/stable with uniform density and superfine finish.
Defects:• Waxy finish on surface. Resin used for manufacture contains
formaldehyde, which is carcinogenic.
Preparation:• Remove dust.
First coat:• Water based primer.• Water based clear coating.• NOTE: Oil bases could react with wax/resin.
Example image:• Customwood
PlywoodThin veneers of wood glued together with the grain running at right angles. Used in furniture, doors and wall panelling. Thickness between 3-25mm depending on the number of veneers or plies.
Properties:• Rigid, porous and absorbent.
Defects:• Varying texture.
Preparation:• Remove dust.
First coat:• Oil or water based primers.• Oil or water based clear coatings.
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Example image:• Plywood
Gyprock PlasterboardA building material composed of a layer of gypsum plaster sandwiched between two layers of kraft paper. Used extensively for lining walls and ceilings, replacing fibrous plaster sheets.
Properties:• Porous, very absorbent. It does not craze like fibrous plaster.
Defects:• Tends to show peaking at flush joints.
Preparation:• Remove dust.
First coat:• Water based sealer.
Example image:• Gyprock
Fibrous Plaster / Plaster GlassA building material made of gypsum plaster and synthetic fibre. Together they form hard rigid sheeting or decorative mouldings. Sheeting has been replaced by plasterboard.
Properties:• Porous, absorbent, smooth faced, chemically active due to a presence of
alkali (usually where jointed).
Defects:• Susceptible to warping, buckling and cracking.
Preparation:• Remove dust.
First coat:• Oil based sealer.
Example image:• Plaster glass
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Hard Plaster / Gypsum PlasterMixed and applied by trowel to provide a hard uniform finish to ceilings or walls.
Properties:• Porous, absorbent and chemically active.
Defects:• If moisture is present, this can lead to efflorescence. Other defects include
saponification, lime burn, poor adhesion of paints, hairline cracking, trowel marks and a loose chalky surface.
Preparation:• Dust and check for moisture/pH levels.
First coat:• Oil based sealer.
Example image:• Hardwall plaster
Fibre Cement (Hardi Sheet)A combination of cement silica, cellulose fibres and water. Available as piping, flat sheeting, corrugated sheeting and planking. Used for exterior lining on timber/metal framed housing, eaves and fences.
Properties:• Porous and absorbent.
Defects:• Check for moisture.
Preparation:• Remove dust.
First coat:• Flat plastic/water or oil based sealer.
Example image:• Hardiflex
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MasonryMasonry materials include bricks, stone, concrete and cement render.
Properties:• Porous, absorbent and chemically active. These materials contain alkaline
salts and other chemicals which may have a detrimental effect on some drying oils in paint.
Defects:• If moisture is present, this can lead to efflorescence. Other defects include
saponification, lime burn and poor adhesion of paints.
Preparation:• Remove dust and check moisture/pH levels. Concrete panels (tilt-up)
must be checked for bonding agents.
First coat:• Water based sealer or alkali resisting oil based sealer.
Example image:• Brick
Ferrous MetalsMetals containing iron, e.g. cast iron, wrought iron, mild steel, high tensile steel and stainless steel. Used for structural purposes.
Properties:• Non-absorbent and corrodible.
Defects:• When iron and steel are exposed to oxygen and water, they quickly
corrode and rust forms on the surface. It is the iron content which causes the rust.
Preparation:• Degrease, wire brush, dust and apply rust converter.
First coat:• Metal primers (that contain zinc).
Example image:• Sheet iron
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Non-Ferrous MetalsMetals containing no iron, e.g. aluminium, zinc, copper, brass, bronze, lead, chromium, cadmium, tin, zincalume, etc. Zinc-coated iron and steel may also be classed as non-ferrous metals, e.g. galvanised iron. Used for structural and decorative purposes.
Properties:• Non-absorbent and corrodible.
Defects:• Non-ferrous metals can corrode when exposed to oxygen and water that
contain impurities. Fine, firmly adhering corrosion deposits are formed which inhibit and slow down the corrosion process. Corrosion can be accelerated by contact with dissimilar metals, acid or alkaline materials.
Preparation:• Dust and degrease.
First coat:• Etch primer or galvanised iron primer for galvanised iron.
Example image:• Zincalume
Plastics (PVC)PVC (polyvinyl chloride) refers to synthetic materials available as mouldings or sheet form; they are usually self-coloured white or grey. Painting is not necessary unless a particular colour is required, e.g. waste pipes and downpipes. Used extensively for moulded spoutings, downpipes and waste pipes.
Properties:• Non-porous and non-absorbent. Smooth surface lacking adhesion.
Defects:• Release agents that remain on surface after manufacture.
Preparation:• Degrease and abrade.
First coat:• Oil or water based paints.
Example image:• PVC pipe
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Expanded PolystyrenePolymerised styrene resin expanded into an extremely lightweight, insulative material which is used extensively for ceiling tile panels.
Properties:• Porous and non-absorbent.
Defects:• Solvent borne paints may dissolve the polystyrene but can be used after
sealing with a water based paint.
Preparation:• Dust.
First coat:• PVA or water based paint.
Example image:• Polystyrene sheet
VermiculiteVermiculite refers to a group of hydrated laminar minerals which are aluminium iron magnesium silicates resembling mica. Pre-mixed vermiculite plasters are available, either gypsum or cement based and can be applied by hand but are usually sprayed to produce an attractive, decorative textured finish on concrete ceilings.
Properties:• Porous, absorbent, clean to handle, non-abrasive, rot proof and good anti-
condensation properties.
Defects:• Vermiculite plasters are tough and resilient rather than hard. They will
indent under impact rather than crack and fall away.
Preparation:• Dust off with broom.
First coat:• Oil or water based paints.
Example image:• Formiculite
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Glass Glazed TilesCeramic tiles have a hard glazed coating applied and fired under high temperatures. Normally not painted. Used on floors and walls in wet and greasy areas.
Properties:• Non-porous and non-absorbent.
Defects:• They are usually very dense, smooth and shiny, providing very little
adhesion for paint.
Preparation:• Do not sand as this will damage the surface. Degrease and abrade using
water and whiting or methylated spirit and whiting. Remove all traces of whiting and paint as soon as possible. Do not allow further contamination.
First coat:• The material used must possess good adhesive properties. There are
paints specially formulated for tiles and laminates.
Example image:• Glazed tiles
End of SubstratesMain Painter: Wow, there sure are a lot of substrates! Now that I know them, can we start painting?Helper Painter: Not so fast! Not all surfaces come in mint condition. You’ll also need to know how to identify problems with substrates and how to prevent and treat them.
Substrate Defects Menu1. Lack of Adhesion2. Bleeding Stains3. Dampness4. Acidic Substrates5. Alkaline Substrates6. Efflorescence7. Corrosive Substrates (Metal)
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8. Mould & Mildew9. Dry Rot10.Wet Rot
Lack of AdhesionDescription:
• Failure of a coating or material to adhere to a substrate.
Common Causes:• Painting over poorly prepared surfaces, e.g. damp and greasy surfaces,
smooth and shiny surfaces, etc.• Formation of rust or efflorescence under painted surfaces.• Expansion and shrinkage of painted surfaces.
Prevention / Treatment:• Ensure that substrates are correctly prepared – they are clean, dry and
free of contaminates, and correctly sealed or primed before application of coatings.
Bleeding StainsDescription:
• Soluble stains that show through a paint coating.
Common Causes:• Occurs when materials such as lipstick, crayon, tar and some inks
permeate paint coatings and show on the surface. • Can also be caused by painting substrates contaminated by smoke and
painting over oily or knotty resinous timbers.
Prevention / Treatment:• Where possible, remove contaminates then seal back with either a stain
sealer or a proprietary bleed sealer.
DampnessDescription:
• Dampness is either due to weather conditions or structural dampness. It can be a problem for paint coatings, causing a lack of adhesion, staining and eventual peeling of the coating.
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Common Causes:• In new buildings, moisture is present in brickwork, plaster, concrete and
masonry. Where an oil based system is used, sufficient time must be allowed for this moisture to dry out prior to painting.
• Rain penetration due to faulty roof flashing, broken tiles, blocked guttering or porous external substrates.
• Rising damp due to absence of or defects in damp proof courses.
Prevention / Treatment:• Ensure adequate protection of substrates from moisture penetration and
ensure that there is adequate ventilation.
Acidic SubstratesDescription:
• Either naturally occurring or environmental factors that lodge acidic compounds on a surface.
Common Causes:• Red Pine, Oak and Cedar are timbers with high acid and oil content.• Cooking fumes in kitchens and pollutants in industrial areas can also be
acidic and cause breakdown of some coatings.
Prevention / Treatment:• For decoration of acidic timbers, use an oil stain finish. Treat acid
affected surfaces like commercial kitchen walls by washing down with a mild alkaline solution (e.g. sugar soap).
Alkaline SubstratesDescription:
• Substrates that contain lime or cement, e.g. cement render, concrete, brickwork, stone, plaster, etc. Also substrates that had paint removers applied or treated with caustic solutions can also be alkaline.
Common Causes:• Painting over alkaline surfaces (e.g. plaster) can cause breakdown of
adhesion in a coating. Painting alkaline surfaces with an oil paint also causes saponification (the reaction between an oil or resin and an alkaline substrate, forming a soapy substance).
Prevention / Treatment:• Allow sufficient drying time of the new substrate. Use a moisture meter to
ensure surfaces are dry enough to be painted and conduct a pH test (do Page 14 of 18
not paint if pH level is over 10). Alternatively, neutralise alkali by treating with mild acid then seal with an alkali resistant sealer or use an acrylic paint system.
EfflorescenceDescription:
• A white crystalline deposit forming on masonry surfaces such as bricks, cement render, plaster and concrete.
Common Causes:• Moisture causes water soluble salts to rise to the surface. When moisture
evaporates, salts remain on the surface.
Prevention / Treatment:• Rectify the cause of moisture contacting the affected substrate. Remove
surface efflorescence by dry brushing. Leave to dry thoroughly. If salts do not resurface, apply an alkali resisting sealer (e.g. a pigmented oil based sealer).
Corrosive Substrates (Metal)Description:
• Corrosion is the deterioration of a metal.
Common Causes:• Chemical attack when metal is exposed to the action of moisture, oxygen,
acid or alkali.• Corrosion can also be caused by contact between dissimilar metals, e.g.
iron and tinplate.
Prevention / Treatment:• Avoid contact between dissimilar metals and use an appropriate metal
primer followed by a coating system that will resist moisture.
Mould & MildewDescription:
• Fungal growth that multiplies and feeds on organic matter.
Common Causes:• This is common in poorly ventilated or damp buildings.
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Prevention / Treatment:• Trace and remedy the cause of dampness. Remove mould and mildew by
washing with an anti-fungicidal solution or a 3:1 mixture of water and household bleach. Leave for 10-20 minutes then rinse off with clean water. Repaint with a paint containing a mould inhibitive agent. If there is a mould stain evident, a suitable oil based sealer will be required prior to applying anti-fungal finishing coats.
Dry RotDescription:
• A fungus that destroys timber. In its early stages, the timber is excessively wet, spongy and covered with fine silvery strands. When timber has dried out, it is brittle and has no strength.
Common Causes:• The fungus develops when timber has a moisture content above 20%, in
humid atmospheres and poor ventilation.
Prevention / Treatment:• Trace and remedy the cause of dampness. Increase ventilation and
remove all infected timber. Treat adjacent timber and new timber with wood preservative or a coating system that resists moisture.
Wet RotDescription:
• Wet rot develops in timber containing 50-60% moisture content. Timber is darkened and cracked with the grain. It becomes spongy and excessively wet beneath a seemingly sound surface.
Common Causes:• External timbers where flaking paint allows penetration of excessive
moisture, e.g. window sills that are consistently wet.
Prevention / Treatment:• Trace and remedy the cause of dampness. If rotting is not too severe
apply timber primer followed by subsequent coatings. For severe cases, remove affected timber, replace with new primed timber and apply subsequent coatings.
ConclusionMain Painter: Wow, that was a lot to take in. I’m glad I checked everything out.
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Helper Painter: Now that you’re more familiar with different substrates and their defects, let’s see what prep you’ll need to do before we start painting.
Credits - FundingThis project was made possible through funding from the National VET E-learning Strategy 2012-2015, a joint initiative of the Australian and state and territory governments (http://flexiblelearning.net.au).For further information on the National VET E-learning Strategy, please contact the FLAG Secretariat:
Phone: (03) 9954 2700 Email: [email protected] Website: flexiblelearning.net.au
Topic 1: Surfaces (Prepare Surfaces for Painting), © Commonwealth of Australia (Department of Industry, Innovation, Climate Change, Science, Research and Tertiary Education), 2013. (http://creativecommons.org/licenses/by/3.0/au)
Credits - ImagesAll images used in this resource are owned by Polytechnic West. © Polytechnic West 2013Information within this resource was current at 2013.
About the National VET E-learning Strategy This project was made possible through funding from the 2012-2015 National VET E-learning Strategy (‘the Strategy’). The Strategy is a joint initiative of the Australian and state and territory governments aimed at strengthening the Australian training sector’s use of new learning technologies; stimulating innovative approaches to increasing participation in training and employment, and improving the skill levels of the Australian workforce (http://flexiblelearning.net.au).
For further information on the National VET E-learning Strategy, please contact the FLAG Secretariat:
Phone: (03) 9954 2700
Email: [email protected]
Website: flexiblelearning.net.au
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Topic 1: Surfaces (Prepare Surfaces for Painting), © Commonwealth of Australia (Department of Industry, Innovation, Climate Change, Science, Research and Tertiary Education), 2013.
With the exception of the Commonwealth Coat of Arms, the Department’s logo, any material protected by a trade mark and where otherwise noted all material presented in this document is provided under a Creative Commons Attribution 3.0 Australia (http://creativecommons.org/licenses/by/3.0/au/) licence.
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