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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
Drying Ceramics Without Cracks
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
Fixing a glaze that does not stay in suspension
Formulating a body using clays native to your area
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 desktop 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
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
Stoneware Casting Body Recipes
Substituting Cornwall Stone
Super-Refined Terra Sigillata
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 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
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 in understanding glazes?
Why Textbook Glazes Are So Difficult

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.


If you have been working with glazes and glaze chemistry for some time, you may have developed a mindset that is too narrow when it comes to dealing with clay body formulation. Clay body analysis is much more of an adventure in mineralogy and physics than it is in oxide chemistry. Two clays of completely different physical properties can have very similar chemistry; two clays of radically different chemistry can have very similar physical and fired properties. Thus on the surface it would seem that chemistry is of little use in formulating and evaluating clay bodies. Actually, this is not quite the case, but it is not far from it.

When glazes melt everything usually goes into solution, but the vitrification process of a clay is quite different. The differences in mineralogy, particle size, firing history, body preparation, and ware forming methods all influence the final fired product. Thus the ability to measure physical clay properties is very important. In this section of the book, I am going to introduce you to some very simple clay tests that you can learn and do. They do not require advanced test equipment and they tell you an incredible amount about a material.

Testing Your Clay Bodies

There is no time to waste in learning how to effectively test your clay bodies and materials. In this chapter I'll outline how you can go about getting a quality control program going on a low budget. Don't let anyone tell you that modern test equipment has supplanted this type of test. You can go into a lab full of million dollar test devices and ask the technicians to describe to you exactly what clay is and I'll bet few could do it in an understandable way that relates to the key reasons why we use clay in ceramics, namely plasticity and vitrification. They could likely show you thousands of numbers from DTA, CoE, XDF, etc. machines, but these are comparative measurements used for quality control, and technicians often lose sight of the reason some properties are even measured. While machines don't measure plasticity well and lab techs don't describe it well (the average potter could talk about the subject at length), it is directly related to shrinkage. The other reason for using clay is that it forms a rock when heated. Porosity and fired shrinkage measurements tell you how complete that process was.

Let us start quickly. Consider the three simple-looking specimens that make it all possible.

Lab testing a clay for its physical properties
SHAB test bars, an LDW tester for water content and a DFAC test disk about to be put into a drier. The SHAB (shrinkage-absorption) bars shrink during drying and firing, the length is measured at each stage. The LDW sample is weighed wet, dry and fired. The can prevents the inner portion of the DFAC disk from drying and this sets up stresses that cause it to crack. The nature of the cracking pattern and its magnitude are recorded as a Drying Factor. The numbers from all of these measurements are recorded in my account at Insight-live. It can present a complete physical properties report that calculates things like drying shrinkage, firing shrinkage, water content and LOI from these measured values.

As you will see, by making the above test specimens for a clay, you will be able to record its absorption and shrinkage over a range of temperatures, its water content, density, dry shrinkage, loss on ignition, soluble salts content, drying performance, glaze-over behavior, and dry strength. While these tests require very little investment in equipment (assuming you already have a gram scale and calipers), there is one testing device you really should buy: a good set of sieves. I will consider these in a separate section.

By doing these tests in a very standarized way, your data will be universal to all other tests that both you and others do (I'll explain what I mean by 'standardized' in a minute). It means you can compare clay properties using real numbers.

As most people have learned, glazes don't travel well. Still, we can compensate for this somewhat with calculations that attempt to preserve a glazes oxide formula into a new setting. But with clay bodies the added dimension of physical properties demands center stage. Unless you can test for them, you cannot even adjust a body let alone 'take it on tour'. For example, while you can usually exchange one kaolin for another in a glaze, such adjustments are likely to have considerable effects on a clay body's drying performance, green strength, fired color, and casting behavior, to mention only a few. Even changing the particle size of a constituent body material can have significant impact.

This subject reveals an interesting comparison between potters and industrial technicians. On one hand, the potter judges a body by how it feels in his hands, how it bends, stretches, pulls, how it behaves on the wheel, how it trims, or how successfully it dries with his ware and techniques. He evaluates it on how it reacts visually with his glazes and fires in his kiln; he dynamically adjusts procedures to compensate for changes he is able to perceive. On the other hand, a ceramic engineer may have never handmade a piece of pottery in his life. As a result, he may not fully appreciate what plasticity is, viewing it merely in terms of how the clay reacts in machines. To him, dried and fired properties exist as numbers produced by test equipment.

Potters often have excellent all-around knowledge; some have remarkable intuitive abilities at evaluating clay bodies; they like to look down at engineers whose cold numbers and charts keep them at a distance from the material. Some potter's textbooks are incredibly insightful and helpful. Yet there is no denying the value of good physical properties testing and hard test results. The ideal is probably a situation somewhere in between these two extremes. Many body properties are immediately evident in the hands of an experienced potter and not quickly shown by instruments. Likewise, differences shown by instruments can explain strange results in the potter's kiln.

There are still many companies in the ceramic industry that do not have a standard testing and quality control program in place. The question is, where does one start to test his clay bodies; how do you set up a simple but relevant program? One answer is an account at It provides a way to define your own test procedures, variables, and equations in keeping with equipment you have. It acts as a platform from which to accumulate unlimited test results and allows you to search, query, and report these results as needed. Being a mature software solution it has a better chance of success than any effort to date.

In a few minutes, I will show you some reports for one of its predefined tests. But first, let us review the options you have with regard to setting up a test program.

Testing Categories:

Universal Standards

An example is the 50-volume Annual Book of worldwide ASTM Standards (American Society for Testing and Materials, 1916 Race St, Philadephia, PA 19103). One of the volumes deals with refractories, glaze, and ceramic materials. The books are well organized and describe all test procedures in great detail. Just reference a test by number and you convey all details about how you achieve your results.

Industry Specific Standards

Individual industries like construction, ferrous metals and electrical porcelain have outlined standard testing guidelines more specific to their needs, for example, ANSI (American National Standards Institute, 1430 Broadway, New York, NY 10018). Companies publish data sheets and advertising material in a format that voluntarily recognizes these standards.

Customer Required

A customer will sometimes require that a manufacturer document quality and compliance of each product shipment. In this case, the client may reference a standard test or define his own test procedure for the manufacturer to carry out. With the advent of quality control standards like ISO 9000, customers are going to the next step and requiring documentation not only on how tests are done, but tolerances, noncompliance procedures, procedure change mechanisms, test equipment calibration schedules, and proof of certification.


Many tests are internal to a company, intended to solve problems, maintain properties critical to production efficiency and cost, control reject rates, etc. In this situation, the manufacturer is quite free to formulate any method that seems best for the circumstances.

Tests have typically required expensive equipment. In the real world, technicians generally have to make do with what is available, so standard methods are usually adjusted. This is not necessarily bad. Simple tests are sometimes most revealing (excellent examples are the Insight-live DFAC and SOLU tests). It is important to think a test through thoroughly, document it, and analyze the information it provides. If you can prove the value of the information, customers will respond positively and production yields and quality will improve.

Implementing a Test

Define the test
Decide what physical properties need to be measured, and if possible, take an existing test procedure (like the Insight-live SHAB test shown below) and redefine it for your needs. If possible, formulate the test to measure as many physical properties as possible. For example, one test bar can be used to measure dry shrinkage, fired shrinkage, and absorption.

Document the test
Using the pattern provided in the SHAB test, clearly set out the reason for the test, the physical properties it will measure, the procedure, and how the results will be used.

Set up the software
Set up your variables in Insight-live, print data entry forms, accumulate test results, print reports in the required format for individual tests, and track testing and problem histories.

Put the test into practice as documented
Carry out the test as defined on a trial basis, make the needed changes, and update the documentation until the bugs have been worked out.

Accumulate tolerance samples
Where a test involves making a subjective observation, accumulate samples that demonstrate the tolerances. For example, if you must record the relative amount of soluble salt discoloration on the fired surface, gather samples to show the worst tolerable amount.

Analyse the results and take corrective action
When test data is accumulated on computer, there is a real danger that the staff will just go through the motions of collecting the information and no one will ever do anything with it. Fine tune the analysis aspects of the test procedure to make sure that at some point, test results are being compared with standards, decisions are made, and actions are taken according to these comparisons. Make sure the procedure definition includes provision for trend reports and historical analysis to help improve plant performance.

Insight-live predefines many tests and the ones of interest to us here are the SHAB (Shrinkage, Absorption), DFAC (Drying Factor), SOLU (Solubles), and LDW (LOI, Density, Water Content). The procedures for these four describe how to make and process the three simple specimens I showed you at the beginning of this chapter (shrinkage bars, H2O bars, drying disk). They also provide a framework within which to gather data.

This is the first part of the Test Procedure report for the SHAB test. It is formatted like a standard ISO 9000 style procedure.

 PROCEDURE NO 02-012-002
DATE: 03/16/97
 1. Purpose of Test
 1.1 This test is designed to measure dry shrinkage, absorption
and fired shrinkage properties. Results from this test are
repeatable if instructions are followed closely.
As a clay dries the removal of interparticle water causes the
mass to tighten up and pack together resulting in shrinkage.
Clays of fine particle size and those of high plasticity have
high shrinkage. Unfortunately the benefits of plasticity are
offset by drying problems. Variation in drying shrinkage is an
indicator of changes in a clays plasticity. However comparing
the dry shrinkage of different types of clay is not necessarily
in indicator of their comparative plasticity since some fine
clays are not plastic. Note that higher water content also means
greater dry shrinkage.
 For typical modeling stiffnesses dry shrinkage for non-plastic
clays is around while plastic clays which require care in drying
are usually above 7.0%. High shrinkage can be reduced by the
addition of an aggregate however this can produce a matrix where
micro-cracks radiate outward from each of these larger particles
creating a weaker dried and fired product. A low drying
shrinkage is important to successfully dry larger items or ware
of uneven cross section.
 Dry shrinkage is simply the per cent change in length between
wet and dry. The SHAB test provides the data for this property
as follows:
 Wet length - dry length / wet length * 100
 or where a 10 cm marks are stamped on the bar it is simply:
 100 - mm dry length
As a clay fires, it shrinks and particles continue to pack
together. At some point, they begin to break down and react with
each other, fluxes begin to melt and flow, and mineral grains
seed the development of more stable forms. The amount of
shrinkage during firing is thus an indication of the degree to
which the complex "maturing" process has proceeded.

This report shows the variables defined for the SHAB test. Data is to be collected for each variable. It also displays calculated fields and the equations used to derive them from the variable data.

Date: 03/16/97
Four Letter ABBR: SHAB
 Purpose: This test is designed to derive shrinkage and absorption data
by drying and firing clay bars according to a detailed procedure. This
test is recommended over the SAWL test since its fewer variables mean
that you can route results reports to the screen and they will fit
within 80 columns. This test does not account for LOI as does SAWL,
however it is assumed that you will also use the LDW test.
 Much of the theory behind why this test is beneficial is dealt with in
the Digitalfire Reference Database online. Like other tests defined here, it
is assumed that you have an account at to log results.
 This test is meshed with the SOLU, DFAC and LDW tests in that it is very
convenient to perform all four at the same time.
VARIABLES (each shown with VAR NAME & TESTDATA link)
 1) Dry Length...................DRY-LEN " 1"
The distance between the outer edges of
two marks on the dried clay bar as
measured with a set of calipers. These
marks were pressed into the wet bar at
exactly 10 cm apart on the outer edges.
 2) Fired Length.................FIR-LEN " 2"
The length between two marks on the
fired clay bar as measured with a set of
 3) Fired Weight.................FIRE-WT " 3"
The weight in grams of the clay bar
after firing.
 4) Boiled weight................BOIL-WT " 4"
The weight in grams of the clay bar
after boiling for 5 hours and soaking
for 19 and being blotted on a towel.
 5) Fired cone...................CONE " 5"
The Orton cone number to which the bar
was fired. Take the highest cone to show
deformation and interpret it as follows:
 Position Value
~~~~~~~~ ~~~~~
1 oclock n-.4
2 oclock n-.3 For example, if
cone 6 is at 3 oclock, then the
3 oclock n-.2 value is 6 minus
.2 = 5.8.
4 oclock n-.1
5 oclock n
 If the guard cones shows deformation you
must increase the figure appropriately.
 6) Ring diameter................RING " 6"
The diameter of a bullers ring which has
been included in the firing. This ring
must be on edge in a holder to allow
heat access from all sides.
 7) Bar color....................COLOR " 7"
The color of the bar (e.g. GOOD, DARK,
 1) Fired Shrinkage..............F SHR " 1"
 EQUATION: IF(V[1]>0 .AND. V[2]>0, str((V[1]-V[2])/V[1]*100,6,2)+"%", " n/a")
 This is the fired component of total shrinkage. Note that dry+fired
shrinkage does not equal total shrinkage because fired shrinkage is
based on the dry length not the original 10 cm.
 2) Dry Shrinkage................D SHR " 2"
 EQUATION: IF(V[1]>0, str(100-V[1],5,1)+"%"," n/a")
 This is the shrinkage due to drying only. Assuming 10 cm marks on
the wet bar, drying shrinkage is simply 100 mm minus the dry length
in mm.
 3) Aborption....................ABSORP " 3"
 EQUATION: IF(V[3]>0 .AND. V[4]>0, str((V[4]-V[3])/V[3]*100,5,1)+"%"," n/a")
 This is a measure of the clays fired maturity as interpreted from
its pore space. The pore space is calculated from the increase in
weight a bar experiences during boiling in water.

This report is actually a form that can be given to your assistants to use to record data as it is collected. The data from these forms can then be keyed into


Variables to measure are:
DRY-LEN - Dry length of unfired thoroughly dried bar (assuming that 10cm marks were pressed into bar when it was wet)
FIR-LEN - Fired length of bar
FIRE-WT - Weight of bar after firing
BOIL-WT - Weight of bar after 5 hour boil and 19 hour soak
CONE - Orton cone to which bar was fired
RING - Bullers ring measure after firing
COLOR - Color judgement on fired bar.

|                 |           |         |        |        |        |        |        |        |        |
|                 |           |         |        |        |        |        |        |        |        |

This test results report was generated from a record for which test data has been accumulated.

*TEST Definition reports are available for tests results shown
DATE: 02/25/97
This is a series of bodies that were mixed after reading Dave Beumee's
article in Ceramics Monthly January 1994.

Nepheline syenite melts faster than the potash feldspars so this body may
tend to warp more.

Compared to the other porcelains tested, this has excellent workability,
the best translucency, excellent whiteness, no absorption, slight
slumping, 17.5% shrinkage at cone 10 and glaze fit of GTS-3-10 (see

I made one vase and transparent glazed it. The bare surface fired was
probably smoothest and it was was the darkest fired color. It reacted
visually with the glaze the same as the others.


6  |95.56  |86.65  |35.82  |35.83  |6.7  |     |     |   9.32  4.4%  0.0% 
7  |95.65  |86.9   |35.42  |35.43  |6.9  |     |     |   9.15  4.3%  0.0% 
8  |95.73  |87.16  |38.31  |38.31  |7.7  |     |     |   8.95  4.3%  0.0% 
9  |95.51  |87.5   |41.27  |41.28  |9.2  |     |     |   8.39  4.5%  0.0% 
10 |95.56  |88.55  |40.6   |40.6   |9.7  |     |     |   7.34  4.4%  0.0% 
11 |95.75  |88.86  |41.86  |41.92  |10.9 |     |     |   7.20  4.3%  0.1% 
12 |95.74  |86.11  |40.47  |40.47  |10R  |     |     |  10.06  4.3%  0.0% 


DRY_FAC - A000

LOI/Water Content (ID-LW, ABBR-LDW )

1 |33.49  |26.34  |24.7    |26.6 7 |11.9   | 21.3%   6.2% 1.81 g/cc 

1 |NIL  |      |     |

Compiling test bar shrinkage and weights for Insight-live
A batch of fired test bars, organized by temperature, have already been weighed (the weight is written on the side of each bar). Now they will be measured and the SHAB test data (shrinkage/absorption) entered into each recipe record (in an account at From this data Insight-live can calculate fired shrinkage and fired porosity, enabling you to compare the degree of vitrification of different materials and bodies. This is especially good for quality control purposes.

The end-product of all your clay body testing work is to generate 'real numbers' that mean something;reliable numbers that can be compared with others to reach conclusions. While the above report may appear a little foreign, it all comes together when you see it in terms of the structured set of variables which are defined for each test. This is a basic report showing gathered data and the results of equations applied to that data. But it is a beginning of a flexible testing system on which much more graphical reports can be built.

So my advice is simple. Set up a little lab for yourself and take control of the physical properties of your clay bodies and materials.

Related Information

Measuring shrinkage/absorption test bars in 1983 at Plainsman Clays

Data for hundreds fired clay test bars was logged into a portable Epson custom programmed HX-20 computer and uploaded to a Radio Shack TRS-80 Model III where it was stored first on cassette, then floppy disk, then a loop tape. That data was later migrated to the Digitalfire DOS 4Sight lab record keeping system (as SHAB specimens) where it lived for more than 27 years (expanding to more than 200,000 tests) until being imported to an account in 2014.

A batch of fired clay test bars in the Plainsman Clays lab

A batch of fired test bars that have just been boiled and weighed, from these we get dry shrinkage, fired shrinkage and porosity. Each pile is a different mix, fired to various temperatures. Test runs are on the left, production runs on the right. Each bar is stamped with a code number and specimen number (the different specimens are the different temperatures). The measurements have all been entered into our group account at Now I have to lay out and photograph each pile and upload the picture into the code-numbered record. Upon doing so I compare color and tests results to make decisions on what to do next (documenting these in insight-live).

Making a humidity drying chamber - How?

The ideal drying chamber is a tunnel. Starter tunnels pass wheeled-ware-carts single file. Hot dry air enters where the ware exits. The moving air touches all surfaces and picks up humidity as it moves toward the ware entrance. The tunnel must be calibrated so that air reaching the entrance, is still very warm, but of high humidity (laden with water it got from ware down the tunnel). When an equal volume of ware is passing constantly, manual calibration of cart movement, air volume and temperature is possible. But if flow is not constant then your "dynamic system" needs multi-location monitoring and intervention. Locating wireless thermometer/hygrometers and actuators is a good early-start to the project. ESP8266 controllers are revolutionizing industrial control. As cheap as $5, they are tiny but completely capable battery-powered WIFI servers. One of these little things can email you! Even display a web page. These communicate with a central dashboard online (in-plant control systems are now obsolete). There are many online dashboard services that talk to these devices and display results graphically. And it is easy to make your own. Hiring a technician on to design a system for you is only a matter of a few thousand (even hundreds) of dollars. Shown here is an Amazon listing for a development kit of an 8266, sensor and cables. I included a listing for a ready-made one, but it is expensive, not well described. A similar product line sells under the name "SensorPush".

Global supply chain issues? Learn to mix and adjust your own bodies, glazes

Shipping containers piled high

Material prices are sky rocketing. And, the more complex your supplier's supply chain the more likely they won't be able to deliver. How can you adapt to coming disruption, even turn it into a benefit? Learn to create base recipes for your glazes and even clay bodies. Learn now how to substitute frits and other materials in glazes (get the chemistry of frits you use now so you are ready). Even better: Learn to see your glaze as an oxide formula. Then calculate formula-to-batch to use whatever materials you can get. Learn how to adjust glazes for thermal expansion, temperature, surface, color, etc. And your clay bodies? Develop an organized physical testing regimen now to accumulate data on their properties, learn to understand how each material in the recipe contributes to those properties. Armed with that data you will be able to adjust recipes to adapt to changing supplies.


Tests Pyrometric Cone Equivalent
Tests Sieve Analysis Wet
Tests Dry Strenth (Round Bars)
Tests Dry Strength (Square Bars)
Tests Density (Specific Gravity)
Tests Soluble Salts
Tests Drying Shrinkage
Tests Firing Shrinkage
Tests Dry Strength (kgf/cm2)
Tests LOI/Density/Water Content
Tests LOI (100-1000C)
Tests Sieve Analysis Dry
Tests Shrinkage/Absorption Test
Tests Sieve Analysis 35-325 Wet
Projects Tests
Glossary Firing Shrinkage
During drying, clay particles draw together and shrinkage occurs. During firing the matrix densifies and shrinkage continues. More vitreous bodies shrink more.
Glossary Drying Crack
During drying clays and porcelains shrink as they become rigid. When this occurs unevenly, cracks are the result.
Articles How to Find and Test Your Own Native Clays
Some of the key tests needed to really understand what a clay is and what it can be used for can be done with inexpensive equipment and simple procedures. These practical tests can give you a better picture than a data sheet full of numbers.
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 Stoneware Casting Body Recipes
Some starting recipes for stoneware and porcelain with information on how to adjust and adapt them

By Tony Hansen

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