A Low Cost Tester of Glaze Melt Fluidity
A One-speed Lab or Studio Slurry Mixer
A Textbook Cone 6 Matte Glaze With Problems
Adjusting Glaze Expansion by Calculation to Solve Shivering
Alberta Slip, 20 Years of Substitution for Albany Slip
An Overview of Ceramic Stains
Are You in Control of Your Production Process?
Are Your Glazes Food Safe or are They Leachable?
Attack on Glass: Corrosion Attack Mechanisms
Ball Milling Glazes, Bodies, Engobes
Binders for Ceramic Bodies
Bringing Out the Big Guns in Craze Control: MgO (G1215U)
Ceramic Glazes Today
Ceramic Material Nomenclature
Ceramic Tile Clay Body Formulation
Changing Our View of Glazes
Chemistry vs. Matrix Blending to Create Glazes from Native Materials
Concentrate on One Good Glaze
Cone 6 Floating Blue Glaze Recipe
Copper Red Glazes
Crazing and Bacteria: Is There a Hazard?
Crazing in Stoneware Glazes: Treating the Causes, Not the Symptoms
Creating a Non-Glaze Ceramic Slip or Engobe
Creating Your Own Budget Glaze
Crystal Glazes: Understanding the Process and Materials
Deflocculants: A Detailed Overview
Demonstrating Glaze Fit Issues to Students
Diagnosing a Casting Problem at a Sanitaryware Plant
Duplicating Albany Slip
Duplicating AP Green Fireclay
Electric Hobby Kilns: What You Need to Know
Fighting the Glaze Dragon
Firing Clay Test Bars
Firing: What Happens to Ceramic Ware in a Firing Kiln
First You See It Then You Don't: Raku Glaze Stability
Formulating a Clear Glaze Compatible with Chrome-Tin Stains
Formulating a Porcelain
Formulating Ash and Native-Material Glazes
G1214M Cone 5-7 20x5 Glossy Base Glaze
G1214W Cone 6 Transparent Base Glaze
G1214Z Cone 6 Matte Base Glaze
G1916M Cone 06-04 Base Glaze
G1947U/G2571A Cone 10/10R Base Matte/Glossy Glazes
Getting the Glaze Color You Want: Working With Stains
Glaze and Body Pigments and Stains in the Ceramic Tile Industry
Glaze Chemistry Basics - Formula, Analysis, Mole%, Unity, LOI
Glaze chemistry using a frit of approximate analysis
Glaze Recipes: Formulate Your Own Instead
Glaze Types, Formulation and Application in the Tile Industry
Having Your Glaze Tested for Toxic Metal Release
High Gloss Glazes
How a Material Chemical Analysis is Done
How INSIGHT Deals With Unity, LOI and Formula Weight
How to Find and Test Your Own Native Clays
How to Liner-Glaze a Mug
I've Always Done It This Way!
Inkjet Decoration of Ceramic Tiles
Interpreting Orton Cones
Is Your Fired Ware Safe?
Leaching Cone 6 Glaze Case Study
Limit Formulas and Target Formulas
Low Budget Testing of the Raw and Fired Properties of a Glaze
Low Fire White Talc Casting Body Recipe
Make Your Own Ball Mill Stand
Making Glaze Testing Cones
Monoporosa or Single Fired Wall Tiles
Organic Matter in Clays: Detailed Overview
Outdoor Weather Resistant Ceramics
Overview of Paper Clay
Painting Glazes Rather Than Dipping or Spraying
Particle Size Distribution of Ceramic Powders
Porcelain Tile, Vitrified or Granito Tile
Rationalizing Conflicting Opinions About Plasticity
Ravenscrag Slip is Born
Recylcing Scrap Clay
Reducing the Firing Temperature of a Glaze From Cone 10 to 6
Single Fire Glazing
Soluble Salts in Minerals: Detailed Overview
Some Keys to Dealing With Firing Cracks

Substituting Cornwall Stone
Super-Refined Terra Sigillata
The Black Art of Drying Ceramics Without Cracks
The Chemistry, Physics and Manufacturing of Glaze Frits
The Effect of Glaze Fit on Fired Ware Strength
The Four Levels on Which to View Ceramic Glazes
The Majolica Earthenware Process
The Physics of Clay Bodies
The Potter's Prayer
The Right Chemistry for a Cone 6 MgO Matte
The Trials of Being the Only Technical Person in the Club
The Whining Stops Here: A Realistic Look at Clay Bodies
Those Unlabelled Bags and Buckets
Tiles and Mosaics for Potters
Toxicity of Firebricks Used in Ovens
Trafficking in Glaze Recipes
Understanding Ceramic Materials
Understanding Ceramic Oxides
Understanding Glaze Slurry Properties
Understanding the Deflocculation Process in Slip Casting
Understanding the Terra Cotta Slip Casting Recipes In North America
Understanding Thermal Expansion in Ceramic Glazes
Unwanted Crystallization in a Cone 6 Glaze
Using Plaster Bats
Variegating Glazes
Volcanic Ash
What Determines a Glaze's Firing Temperature?
What is a Mole, Checking Out the Mole
What is the Glaze Dragon?
Where Do I Start?
Why Textbook Glazes Are So Difficult

Stoneware Casting Body Recipes

Description

Some starting recipes for stoneware and porcelain with information on how to adjust and adapt them

Article

Here are a couple of starting recipes for casting stoneware bodies. It is assumed, of course, that you might need to make adjustments. Remember that property adjustments are always on a trade-off basis. If you want a super white body, for example, you are going to have to give up some working properties.

Once you get a feel for why each of the materials is in a porcelain or stoneware body you will find that balancing all of the factors involved will lead you toward only one possible recipe. For example, you need enough silica so glazes will not craze and enough feldspar to vitrify the body. That leaves the remainder for clay which you can mix and match for your needs. If two researchers are given a clear description of the properties needed in a porcelain, the way it will be fired and the set of materials to work with they will come up with the same recipe.

Cone 6 Porcelain Clay Slip

Silica

15.0

Ball clay

19.0

Kaolin

19.0

Nepheline Syenite

45.0

Talc

2.0

Talc is not a strong flux at cone 6, but for some reason small amounts can have a marked effect on the development of maturity (only 1% can reduce the porosity by 1%). At cone 6 it takes a lot of feldspar to vitrify the body, nearly twice as much as for cone 10. This recipe will deflocculate to 1.8 specific gravity and will fire to produce vitrified ware that is extremely strong and durable compared to typical artware. It has a long firing range and can produce ware of excellent translucency with clays of low titanium content.

Cone 10 Whiteware Clay Slip

 

Silica

25.0

Ball clay

25.0

Kaolin

25.0

Feldspar or Nepheline Syenite

25.0

At cone 10 much less feldspar is needed. Thus there is more room for clay and silica in the recipe. If you decide to reduce the ball clay in favor of kaolin, remember that the former contributes quite a bit of quartz and thus glazes might craze. To compensate you might have to increase the silica to 30.

Deflocculation

Deflocculation refers to the magic process of creating a slurry with only half the amount of water that would normally be necessary (see the link to an article on this topic). Generally you measure the water and put it into a container, start your propeller mixer and add most but not all of the deflocculant. Then you add the powder body mix. The slurry becomes very heavy so you need a powerful mixer than can run for hours. Getting the last bit of powder to mix in can take some time so patience is required.

Powder Mix 100

Water

36.0% of dry amt

Soda Ash

0.05-.1% of dry amt

Sodium Silicate

about 0.2 to 0.3% of dry amt

or

Water

36% of dry amt

Darvan

0.5% of dry amt

Note that water and deflocculant amounts are examples, you need to know how to measure specific gravity and viscosity to adapt their amounts to your materials and water (see the article on deflocculation for more information).

Comparison to Low Fire Artware Casting Bodies

I emphasize again that these bodies are not as robust as a ball clay:talc low fire casting slip used in the hobby casting industry. These bodies will present more mold release problems, green strength will be lower, and you simply will not be able to use some of the molds that work well with talc slip. Also, it is important to have molds that have smooth surfaces; rough porous surfaces provide too many places for the slip to 'hang on' and you will have even more release problems. If necessary do a dusting of talc on problem mold areas where pieces will not release. If pieces do not have the strength to shrink away from the mold without pulling apart consider using a plastic kaolin (e.g. #6 Tile). These will greatly increase the strength (don't assume a kaolin is plastic because people tell you it is, slurry up, dewater and evaluate the ones you have to determine which is most plastic).

Brown Burning Casting Bodies

It is generally best not to use iron oxide additions, they tend to gel the slurry. Rather, employ a high iron clay like the American Redart, Banta or Carbondale materials in place of some or all of the ball clay and kaolin.

When Money is No Object

If you are willing to spend extra money you can greatly improve your casting slip. For example, it is amazing how much zirconium silicate additions can whiten the fired product. Likewise, the use of micro-fine calcined alumina instead of silica will drastically increase fired strength and whiteness and reduce thermal expansion. The use of a body frit will enable you to make a lower firing body. Blue stain can be added to brighten color or a decolorizer like antimony can be added to cancel the browning effect of iron. If you have a kiln that will go to cone 20 you can remove most of the feldspar and add other things that impart properties you want. If you know alot about firing and have a kiln in which you can control the gases in the atmosphere you can do some amazing things. There is no real limit to creativity in developing porcelain recipes. Dental porcelain, for example, is a mix of nearly 100% frit, it has almost no plasticity. However it vitrifies at below the bisque temperatures an average potter would use.

Optimimal casting slurry properties impossible without good mixing

A video of the kind of agitation you need from a power mixer to get the best deflocculated slurry properties. This is Plainsman Polar Ice mixing in a 5 gallon pail using my mixer. Although it has a specific gravity of 1.76, it is very fluid and yet casts really well. These properties are a product of, not just the recipe, but the mixer and its ability to put energy into the slurry.

Links

Articles Understanding the Deflocculation Process in Slip Casting
Understanding the magic of deflocculation and how to measure specific gravity and viscosity, and how to interpret the results of these tests to adjust the slip, these are the key to controlling a casting process.
Articles The Physics of Clay Bodies
Learn to test your clay bodies and recording the results in an organized way and understanding the purpose of each test and how to relate its results to changes that need to be made in process and recipe.
Articles Formulating a Porcelain
The principles behind formulating a porcelain are quite simple. You just need to know the purpose of each material, a starting recipe and a testing regimen.
Articles Low Fire White Talc Casting Body Recipe
The classic white ball clay talc casting and modelling recipe has been used for many years. It is a dream to use as long as you are aware of the problems and risks.
Articles Understanding the Terra Cotta Slip Casting Recipes In North America
This article helps you understand a good recipe for a red casting body so that you will have control and adjustability.
Glossary Glaze Chemistry
Glaze chemistry is the study of how the oxide chemistry of glazes relates to the way they fire. It accounts for color, surface, hardness, texturem, melting temperature, thermal expansion, etc.
Glossary Deflocculation
The deflocculation process is the magic behind the ceramic casting process. It enables you to make a slurry of far lower water content and thus lower shrinkage.
Glossary Stoneware
To potters, stonewares are simply high temperature, non-white bodies fired to sufficient density to make functional ware that is strong and durable.
URLs http://www.baileypottery.com/books/molds.htm
More books on Casting
URLs http://www.bigceramicstore.com/Books/slipmolds.htm
Books on Casting

By Tony Hansen


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