Ceramic Glazes 2ndEd

7/27/2019 Ceramic Glazes 2ndEd

http://slidepdf.com/reader/full/ceramic-glazes-2nded 1/16

getting the most out of

ceramic glazesand underglazes

using commercial ceramic glazesand underglazes to achieve

color, depth, and complexity

| Second Edition |

This special report is brought to you with the support of Mayco

ceramicartsdail y.org

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A World of Colorby David GambleUnderglazes are one o the most popular ways to add color to clay suraces. They’re easy to use, and underglaze colors

are pretty much a “what you see is what you get” kind o proposition—blue fres blue and orange fres orange. The

best part is that underglazes come in all orms like underglaze pens, underglaze pencils, underglaze crayons, and more.

Homemade Underglazesby Holly GoringUnderglazes are widely avaialble but i you’re adventurous, you may want to try to mix your own. Holly provides a basic

recipe and instructions or creating your own underglazes and the special instructions required or success.

Creating a Weathered Look

by Jeffrey NicholsJeery explains how he discovered a weathered surace eect using underglazes on his precision-made teapots.

Discover how he does it using underglazes and sandpaper and give it a try on your next pot.

Using Ceramic Underglazesby David L. GambleCommercial underglazes are a great way to add color to your work using a variety o application methods. They’re ormulated

to have low drying shrinkage, they can be applied to bone-dry greenware or to bisque-fred suraces. In addition to being

able to change the surace color o your clay body, underglazes can also be used to change the texture o the body.

Creating Depth with Ceramic Glazeby Lisa Bare-CulpThere are many ceramic glazes that look great all by themselves, but you can really bring your own style and voice orward

when you start using techniques like pouring, carving, and layering to create depth in the ceramic glaze surace.

Low-Fire Red GlazesBy David L. GambleI you have ever tried to ormulate a red glaze, you know how difcult it can be. But even i you buy commercial red

glazes, you understand that they need a certain amount o attention and precision paid to them during application and

fring. This article will help you understand and keep track o all the variables when applying and fring red ceramic glazes.

Getting the Most out of Ceramic Glazes and Underglazes Using Commercial Ceramic Glazes and Underglazesto Achieve Color, Depth, and ComplexityCeramic glazes and underglazes are varied and wondrous concoctions. Because they can be complex, as well as or

ease o use and time savings, most o us use commercial ceramic glazes to some extent. Chances are, even i you are aceramic glaze mixing master, you have a ew commercial ceramic glazes or underglazes around the studio or specifc pot-

tery applications. Maybe you want to rely on commercial glazes or your liner glaze, so you’re sure it will be ood sae, or

perhaps a commercial ceramic glaze provides that hard-to-ormulate color you need or details in your surace decoration.

Getting the Most out of Ceramic Glazes and Underglazes: Using Commercial Ceramic Glazes and Underglazes to

Achieve Color, Depth, and Complexity provides several approaches and techniques to successully identiying, applying

and fring commercial ceramic glazes.



A World of Color

Company Product Colors Cone

Amaco LUG 24 06–5Velvets 59 06–5

Velvet One Strokes 12 06–5

Sun Strokes 6 06–05Semi-moist (pan) 48 06–5

Pencils 6 06–5

Chalk Crayons 16 06–5Tubes 48 06–5

Engobes 9 05–6

A.R.T. Glazewerks 34 06–04

Axner Pencils 15 06–5Pens 27 06–5

ChromaColour

International Underglaze 100 06–05 Underglaze 50 6

Underglaze 63 10

Speckled

Underglaze 12 06–05

Continental

Clay Underglaze 40 06–6

Coyote Clay& Color Underglaze 25 5–10

Duncan CoverCoat (opaque) 7 06–5E-Z Stroke (translucent) 69 06–5

Gare Underglaze 55 06–5

One strokes 21 06–5

Great Lakes Underglaze 24 06–6

Kickwheel Underglaze 12–18

Laguna EM Underglaze 72 06–6

Mayco Underglaze

(opaque) 70 06–5One Strokes

(transparent) 32 06–5

Minnesota Clay Underglaze 16 06–9Underglaze Pads 8 06–8

Choxilis Pencil 10 06–8

Potters slip 10 06–9

Rovin Ceramics Underglaze 12 06–8

Spectrum Underglaze 70 06–5

One Stroke 40 06–5

Speedball Underglaze 24 06–6

Standard Clay Underglaze 23 06–5Underglaze Painting Medium

quantities, and in dierent ormats, such as crayons, pencilsand pens. I you’re not sure what you’d like to do, order2 oz. bottles and experiment beore you invest in pints orgallons. Here is a partial listing o oerings, but rememberthat most o the companies listed here sell their productsthrough distributors. For more inormation, go to the com-pany websites or check with your local supplier.

Underglazes are oneo the most popular

ways to add color to claywork. They’re easy to useat any age or skill leveland they can be applied atboth the green and bisquestage o work. Underglaz-es come in many orms—liquid, powder, pencil,crayon, liquid writers, bot-tle applicators, underglazepads, watercolor-type pan

sets and tubes. Typically,liquid underglazes containgum or binders to help

them adhere to ware and also add some green strength.I you decide to purchase dry underglaze, you may alsoneed a mixing medium, or example, Standard Ceramicsspecies mixing one part colorant and one part mixingmedium. The medium adheres well and creates a hardersurace than water so there is less smearing i you’reworking on bisque and placing a clear glaze on topbeore ring.

Underglaze pencils, crayons and chalks vary depend-

ing on the manuacturer. They’re designed to be usedon bisqueware because rubbing them onto a ragilegreenware surace can break the greenware. Pencilsproduce a nice pastel or a pencil-type eect dependingon how smooth the clay surace is. Many are very dry

and break easily duringapplication, and most areimported rom outside theU.S. Some pencils containwaxes to help them adhereto a bisque surace, butthese need a clear glaze

on top to keep them romrubbing o ater they’rered. Caution: Never putunderglaze pencils in anelectric pencil sharpener.

Many companies oerunderglazes by dierentbrand names, but they allpretty much unction thesame way. Underglazescome as premixed liquidsor dry, large and small

Test all underglazes or yourstudio conditions—clay body,fring, overglazes, etc. Createtest tiles with samples andapply a clear overglaze to halthe swatch. You’ll fnd thecolors deepen in value with aclear glaze.

Underglazes are the mostversatile o products or theclay artist. Available in morethan 1000 colors, underglazes

come in both dry and liquidorm as well as pencils, cray-ons and chalk.

by David L. Gamble



Homemade Underglazeby Holly Goring

The truth is, I was a nerdy ceramics undergradu-ate student. I wanted to learn everything, right

away—and I loved my glaze calc class. No, re-

ally, I did. I took a ridiculous amount o notes and then

put them all in plastic sleeves in a binder. I’m sure I

tested every recipe I could nd or invent. Ater discov-

ering commercial underglaze, I was sure I could make

that too.

Smooth, silky, perectly opaque, commercial under-

glaze is that wonderul substance that coats and colors

both greenware and bisque ware with ease (I’ve even

seen it work on mature cone 04 earthenware), and

without faws. And, in terms o color, what you see

is what comes out o the kiln, no guessing, no hop-

ing. They are dependable as well; covering large areas

quickly with smooth and consistent brush painting.They take light-colored, transparent or clear glazevery well without dissolving into the glaze during

the ring. Finally, commercial underglaze res intoa hard, unscratchable surace without pinholing orfaking rom cone 04 all the way to cone 10.

Commercial UnderglazesToday, most commercial underglazes are ormulatedusing rits, which reduce shrinkage, allowing themto be applied to both greenware and bisqueware.They are produced using a colloidal process. A col-loid is a substance microscopically dispersed evenlythroughout another substance (think mayonnaiseor hand cream). Underglaze manuacturers use a

chemical process that employs a high-shear mixingtechnology to create colloids. The substance createddoes not settle and cannot be separated out by ordi-nary ltering or centriuging like those in a typicalsuspension. This allows or complete integration o all raw materials, including the colorant, during thebase mixing stage.

Underglaze applied over red earthenware. White slip was applied to hal o the test tile beore bisque fring. This is no-ticeable in the white, orange, and red tiles where the application was thinner. See recipe on next page.



Developing the RecipeVariations o underglaze recipes were available onthe Internet but not much could be ound in text-books, beyond iterations o slips (clay suspended inwater, ormulated to t either to wet or dry green-

ware) and engobes (generally a lower clay content,most oten ts greenware and bisque ware ). Few o these recipes encompassed all the characteristics Iwas looking or—something similar to commercialunderglaze. Not too much to ask, right?

I started by choosing a clay and a fux. I neededa airly heavy clay content or adhesion to the claybody, and an equal amount o fux to lower themelting point o the silica, and to create a hard sur-ace. My clay choices included: EPK kaolin, calcinedkaolin, OM-4 ball clay, and talc, all airly whitering as to not add to the color, and each contrib-

uting something dierent to the adhesion needed.My fuxes consisted o: Ferro rits 3124, 3134, and3195, a good place to start in terms o readily avail-able rits. Then in a radical move, I ignored all previ-ous instruction and treated the colorant as one o thebase ingredients. This allowed or ull incorporationo the color with the other two ingredients duringthe mixing o the base recipe. I used commercialstains in order to get an opaque quality (I later testedvariations with oxides that resulted in a somewhattransparent underglaze.)

I mixed 1000 gram batches in a thousand varia-

tions (or something close to that). I actually mixedthree batches o each recipe to test gums and sus-penders, without which, any substance mixed romthe above ingredients would settle to a rock-hardmess and be nearly impossible to brush onto anyclay surace. I tested CMC gum (powder, premixedinto a liquid), premixed bentonite, and Sta Flo laun-dry starch (a tip rom one o the internet recipes).

Not having the ability to replicate the colliodalprocess, I sieved and ball milled each recipe in orderto ully integrate the raw materials and to reduce theparticle sizes as much as possible.

I tested each glaze on leather-hard, bone-dry, andbisqued earthenware and stoneware test tiles. I redthe earthenware tests to cone 04 and the stonewaretests to cone 6 and cone 10, all in an electric kiln.

Ater many rings and many eliminations, thisrecipe came very close to replicating commercialunderglaze:

Holly’s UnderglazeCone 04–10

Ferro Frit 3124 333 %

EPK Kaolin 334

Commercial Stain 333100.0 %

Sieve all materials with an 80 mesh sieve and then ballmill for at least 12 hours. Incorporate Sta Flo LaundryStarch until the mixture reaches a thin yogurt consistencyand sieve the entire mixture again.

Pros and ConsThe results were good, very good—smooth,creamy, good adherence, versatile at all tempera-tures, a hard surace, and an intense color. Theunderglaze worked well on both clay bodies and inall stages, but was best on bisque ware. Brushabil-ity was best with the Sta Flo. I ound that too thicko an application caused faking and pinholing.The lack o sieving and ball milling did the same.I mixed to the correct consistency, one coat wassucient while two coats oten was too much. Thecolors became muted when red to cone 10 butstill held up in hardness and adhesion. Only smallbatches could be mixed at a time due to the inclu-sion o the Sta Flo, which is organic and causedmold to grow in the bucket within a ew days. Themold could be skimmed o but added unwantedlumps i it wasn’t all removed. And o course theamount o commercial stain used to produce therich colors similar to commercial underglazeswas ultimately very expensive. In the end, mixingthis homemade underglaze was a lot o work ora product the manuacturers do just a bit better,

aster, and cheaper. However, i I want colors thataren’t available commercially, now I know how tomake them.



by Jeffrey Nichols

Faceted Teapot

During a teapot demo, one o my students will inevitably ask about how long it takes me to

make a teapot, and I usually respond with a dramatic, “20 years!”. This is the answer I give

because that’s how long it’s taken me to develop all the skills I need to successully create the

work I’m now making.

As clay artists and potters, we’re always striving to express ourselves in our own voice. It oten

takes us years to nd that voice because it usually develops out o our experiences, our education,

and our exposure to as many dierent orming and decorating techniques as possible.

Developing the SurfaceAter years o honing my skills, I nally realized that traditional ceramic processes were getting

in the way o my ideas. I wasn’t achieving the results I wanted with my ceramic art. Don’t get

me wrong. I think it’s important or potters to have a comprehensive knowledge o the material

and possess strong cratsmanship skills, but my true artistic voice didn’t develop until I started

making work that began with an idea rst, not a process.

Inspired by the concept o wabi-sabi, the Japanese aesthetic where beauty is ound in things

that are imperect, I began looking or inspiration in non-ceramic suraces. I ound it in suraces

like weathered, painted wood and brick, as well as in nature, within all leaves and spring fow-

ers. I wanted to create works that evoke the same kind o impact that a Rothko painting does.

The ollowing is the process I developed to replicate these kinds o suraces. Ater making a

teapot, bowl or vase rom earthenware, I bisque it to cone 02 and begin spraying the vessel with

multiple layers o Amaco Velvet underglazes. Essentially, I use the Velvets as a high-rit engobe.



You can also layer the underglazes by sponging them

on i you do not have access to a spray booth. I rec-

ommend wearing gloves i you take this approach.

Ater the underglazes have dried, I begin sanding

through the dierent layers exposing the other col-ors, as well as the earthenware clay body underneath.

Again, remember to wear a respirator! I start with

320-grit sandpaper working to a 600-grit surace. I

then re the piece to cone 04, holding it at matura-

tion or ten minutes to create a strong bond between

the clay body and the underglazes.

It is important to apply this surace only to the out-

side o vessels or in areas that do not come in contact

with ood or drink. When red, the Velvets and other

underglazes have the durability o a matt glaze, but

are not ood sae. I then apply a ood-sae liner glaze

to the parts that will come in contact with ood andre the vessel again.

Faceted tea bowl with our layers o underglazessprayed on then sanded o to reveal the layers, giv-ing the piece a weathered look. A black was appliedfrst ollowed by red, light blue then medium blue.

Faceted teacup and saucer with our layers o underglaze(black, red, yellow, and orange) applied then sanded. Anynumber o underglaze colors can be added in any combina-tion—the choice depends on the eect you’re looking or.

Nichols uses a respirator and a hooded exhaust vent tomanage the dust created when sanding his dry suraces.Below is a surace detail revealing the layers o colors.



Using Ceramic Underglazeby David L. Gamble

Commercial underglazes

are basically clay slips

containing colorants, and

they’re a great way to add

color to your work using a variety

o application methods. And since

they’re ormulated to have low dry-

ing shrinkage, they can be applied to

bone-dry greenware or to bisque-red

suraces. In addition to being able to

change the surace color o your clay

body, underglazes can also be used to

change the texture o the body.

When used to add color to sur-aces, underglazes have an advantage

in that they are composed mostly o

clay with very little fux, so they’ll

stay put and won’t run, which makes

them ideal or detailed decoration.

While most underglazes were origi-

nally ormulated or use at low-re

temperatures, most, maintain their

color in the mid range and some even

as high as cone 9 or 10.

Simple ApplicationUnderglazes can be applied by brush-ing, pouring, dipping, spraying,

sponging—pretty much anything

goes. Each application method has

dierent requirements. I an under-

glaze is too thick or spraying or

using as a wash, just add water to

thin it down. I it’s too thin or silk

screening or monoprinting, leave the

container exposed to air to evaporate

some o the liquid.

Underglazes work best with a clear

overglaze, although other glazes o

varying opacity and color may also

be used. I’ve had success with whites

and very light-colored glazes, but

darker glazes seem to muddy or ab-

sorb the color o the underglaze. The

overglaze can be anywhere rom matt

to glossy. You’ll nd the clear deep-

ens the value o the colors regard-

less o application method. I you’re

sealing the surace o work that will

“Teapots” by Jim Kemp. Jim uses a low-fre red clay body and airbrushes under-glazes onto the greenware. The last color he applies is black, which is sprayedacross the piece to highlight the variations in heights o the surace decoration.The pieces are once-fred to cone 02.

come in contact with ood, be sure to

use the appropriate ood-sae clear

that matches your clay body and r-

ing range.

Applying an overglaze can be

tricky. I you’ve applied underglazes

on bisque, you’ll nd that they’ll

smear when brushing on a clear over-

glaze because moist glaze moistens

the underglaze. Use a an brush and

foat the rst coat on without going

over the same area twice. Wait or

the rst coat to dry completely beorebrushing on a second coat.

I’ve recently used underglazes to

create a watercolor eect by thin-

ning them down and painting them

onto a semi-white glaze that is lay-

“3 Women Praying” by Debra Fritts.Debra sculpts in terra cotta clay andbisque fres to cone 02. She thencovers the piece with black stain andthen underglazes are applied, wipedand scraped, then fred to cone 04.She continues with fnal additionsand does a fnal fring at cone 05.





Paul Wandless paints underglazes on plaster in reverse, painting the ore-

ground rst and the background last He then pours a low-re white slip on

the plaster This picks up the underglaze image and inlays it into the clay

Ater bisque ring to cone 02, he applies a thin clear glaze then glaze res

to cone 04

Tom Meunick uses white stoneware or

porcelain then bisque res to cone 06

He then uses underglaze pencils to draw

on the surace Ater drawing, he atom-

izes it lightly with water then applies a

glaze by dipping or spraying

ing with all these colors allows you to nd new

and unexpected results when testing in, on andunder anything you have on the glaze shel.

One thing to remember, however, is that i you’re

using underglazes at a higher temperature than rec-

ommended, things can change. One clay artist using

a black underglaze at cone 10 noticed that the next

pint she opened looked the same in the jar but had a very

greenish cast when red. The company told her they had to

reormulate because o government regulations and material

availability and reormulated the color to t their cone 06 to

5 suggested ring temperatures. The higher cone 10 tempera-

ture was overlooked and not taken into consideration.

Ron Korczyski bisque res a white low-re clay to cone

04 then applies underglaze by brush on the bisque piece

He uses many underglaze colors in dierent size applica-

tors that he can squirt out and draw line details and dots

o color The nal piece is red to cone 05



As a potter and in-home in-

structor or many years, I’ve

always mixed my own

glazes, or relied on other

proessionals who mix dry glazes to

my specications. Recently, an idea

or a single pot challenged me to ex-

periment with commercially-madeglazes. The outcome has been succes-

ul with vibrant new color selections,

time savings and the convenience o

readily available glazes screened or

toxicity—all this without compromis-

ing my workspace or my standards.

What changed my thinking on com-

mercially prepared glazes was my de-

sire to introduce bold new colors into

my work. I envisioned a piece with

contrasting matt black-and-white

slip suraces oset against a single

area glazed in vibrant red. My local

supplier recommended a ood-sae,

nontoxic red glaze, Mayco’s Stroke

& Coat Cone 06.

EarlyExperimentsEarly tests resulted in pieces with

dramatic and beautiul contrastsbetween my porcelain slips and the

red glaze. In one test, I used Stroke

& Coat SC-73 Candy Apple Red,

to highlight areas o bisqueware. In

another, I used SC-74 Hot Tamale.

Sometimes I applied the glaze with

a big brush in a single, expressive

stroke. Other times, I squeezed the

colors rom a slip trailer and a turkey

baster.

Ater these loose applications, I

dipped the entire piece in my usual

cone 6 glazes. Because o their gum

content, the commercial glazes re-

sisted my glazes slightly, making thebold strokes o color come through

vividly. Stroke edges were blended

and their colors sotly striking against

the cone 6 palette. The outcome was

as satisying technically as it was

aesthetically; I was satised with the

melt (Stroke & Coat is a glaze, not

an underglaze), the color and the

absence o pinholing or other major

faws at cone 6.

“Fish Bowl,” mattwhite glaze overcommercial glazes,fred to cone 6.

Creating Depth with Ceramic Glazes

by Lisa Bare-Culp



A New ToolFurther experiments with sgrato,

layering, mixing with slip and stone-

ware glazes, and multiple rings have

opened up commercial glazes as a

new artistic tool—albeit an unex-

pected one—to share with students.

They have learned the importance

o experimenting with new suraces,new materials, combining techniques

and achieving balance with dierent

kinds o material.

I you’d like to experiment with

commercially prepared glazes, I’ve

included three o my projects or you

to try. Mixing my own recipes will

always be an important part o un-

derstanding the science behind the

art o pottery making. But success-

ully integrating commercial glazesin the mix is just one more way to

pursue the unction and beauty o

ceramics.

Asparagus Tray

PouringSqueeze a large amount o Stroke & Coat SC-73 Candy Apple

Red across the interior o a bisque-red bowl Use a 2-inch

brush to apply a thin coat o Mayco’s Elements Chunkies EL

203 Coal Dust (this is a low-re eect glaze with crystals) over

the Candy Apple Red

A nice eathered edge is created when the piece is dipped

into a cone 6 black glossy glaze

Fish Bowl

CarvingApply a thick coat o Mayco Stroke & Coat

SC-71 Purple-Licious and SC-74 Hot Tamale

with a large brush to the interior surace o

a leather-hard bowl Once the colors are

slightly dry, the design is carved throughthe glaze with a loop tool, then bisque red

to cone 08 Dip the entire piece twice in a

cone 6 matt white glaze and re to cone 6 in

oxidation The commercial colors show wel

through the white matt

Note: I the carved lines are too ne they

may ll in when the glaze melts



Gear Dish

LayeringOn a heavily textured, bisque-red piece, apply a cone 6 por-

celain black slip as a stain, wiping o the high spots with adamp sponge

Use a 2-inch brush to apply Stroke & Coat SC-71 Purple-

Licious to the high spots with a dry brush technique Next,

dry brush Mayco’s Stroke & Coat Red SC-74 Hot Tamale and

SC-27 Sour Apple onto the interior Apply a thick coat o the

red glaze in isolated areas to obtain a bright color

Apply wax resist to the interior surace o the piece and

allow to dry Dip the entire piece in a cone 6 blue glaze

“Gear Dish,” slab-built stoneware.



I’ll start by ex-

plaining there are

two dierent types

o commercial red

glazes that I normally use.

One type is an extreme-

ly bright color and harder

to achieve and the other is a

newer tomato red color that is AP(Approved Product o the Arts and

Creative Materials Institute) non-

toxic and dinnerware sae. The latter

is ormulated with inclusion stains,

which are continuing to be improved.

The color is encased in zircon, which

makes them sae to use even in the

classroom.

The AP nontoxic reds are extreme-

ly stable and were used to create red

velvet underglazes that can be red

rom cone 05 to as high as cone 10—only salt seems to blush them out.

The success o underglazes has al-

lowed the development o gloss and

matt red glazes that have been ormu-

lated to work well at the low-re cone

05 range and other glazes ormulated

or the cone 4–6 range. These are ex-

tremely reliable. Three brushed coats

will usually be enough o an applica-

tion and you get nice tomato color

reds at both temperatures.

Bright reds are not dinnerware sae

and are extremely sensitive to varia-

tions in ring conditions. There have

been many times that an art teacher

has asked me about the use o these

types o red glazes. I understand the

space and time challenges that teach-

ers ace, but you cannot put these

glazes in with your normal glaze

rings and expect good results. Theyare aected by how tight the load is

stacked, other glazes (mostly copper

greens), and temperature. I you’re

ring to cone 05, I can almost guaran-

tee there will be problems. The glaze

will most likely have variations rom

clear to gray to black, and i you’re

lucky, a spot or two o red.

Note: Amaco glazes were used in the

pieces shown here, however, many

companies produce similar glazes.

Let: Untitled, byScott Bennett. Amaco

LM series Coral glazewith wax and Blackoverspray. As the waxmelts in the kiln, theblack moves.

Above: Plate, by DavidGamble. Cross is glazedwith red underglaze.

Low-Fire Red Glazesby David L. Gamble

ProcessHere are my suggestions o what you

need to know and do to achieve the

bright reds!

Bisque your clay body slowly to

cone 04 (12 hours to get all the gases

out). Although these glazes are not

considered translucent, the clay body

color does aect them slightly. White

bodies will make the glaze appear

brighter in color than darker bodies.



“Redhot Chilli Pepper Diner,” by Jerry Berta. Glazed with red underglazes.

Using a brush, apply the glaze

thicker than the normal three coats.

Four coats will usually work, but too

heavy an application may cause the

glaze to run. Glaze application may

need experimentation and practice.

Load the kiln very loosely. There is

a need or lots o space between the

pieces or air circulation. I leave the

peephole plugs out during the ring,

thus allowing extra oxygen to enterthe kiln chamber.

Do not re above cone 06 (1828°F),

preerably using witness cones or

observation. I have been ring at

cone 07 (1789°F) with great results.

These glazes seem to like the cooler

temperatures.

Fire as quickly as you can, our

hours is ideal. I your pieces are larg-

er, an example being my 22-inch plat-

ters, take them up slowly to about

1200°F. This may help to eliminate

cracking problems. Then turn the

kiln on high to ast re to the end o

the ring.

More ObservationsI your kiln is vented through the

bottom with a system that draws air

through the top o the kiln, this will

help give you more oxygen in the kiln

and better red results. Remember that

kilns, depending on how they are

stacked, may not re that evenly. This

can cause cold spots and hot spots.

There can be a dierence in tempera-

ture equal to a couple o cones rom

top to bottom—depending where the

kiln sitter or thermocouple is locat-

ed. This variability can really aect

bright red glazes. Newer kilns with

zone control and multiple thermo-

couples tend to re more evenly. I you have an older kiln, place cones

in the top, middle and bottom o

the kiln so you can keep a record o

what happens in the ring. They can

help provide answers i problems do

occur.

Now that you know the processI will describe my experimentation

with red glazes. I’ve been placing

them on dierent color clay bodies

layering over glazed red pieces and

layering one coat o gold glaze over

the top.

I then place the pieces next to peep

holes to brighten the color or place

shelves over the edges to deepen and

take away the color. This is what is

exciting to me—not getting it perect

but having the surace color changeand vary while having some contro

over what the changes will be. I am

an extreme advocate o using com-

mercial glazes the way a painter

would use his tubes o paint. Experi

ment, test to the “max” and make

them your own. Years ago, I was

asked to be a glaze doctor at the Na

tional Council on Education or the

Ceramic Arts (NCECA) in Las Ve

gas. I agreed, but told them to labe

me a glaze deviate instead o a glaze

doctor.

Don’t be araid to experiment

Don’t be araid to sacrice a ew

pieces on the way to discovering

something more exciting.

Platter, by David Gamble, glazed with red glaze, blue brush strokesand one coat o gold used or accents.



http://www.maycocolors.com/

Documents

Ceramic Glazes 2ndEd