A Low Cost Tester of Glaze Melt Fluidity
A One-speed Lab or Studio Slurry Mixer

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 Clear Glaze Compatible with Chrome-Tin Stains
Formulating a Porcelain
Formulating Ash and Native-Material Glazes
Formulating Your Own Clay Body
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
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
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 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
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

A Textbook Cone 6 Matte Glaze With Problems

Description

Glazes must be completely melted to be functional, hard and strong. Many are not. This compares two glazes to make the difference clear.

Article

The picture below is a flow tester that was fired at cone 6. The tester itself is Plainsman M370. The glaze on the right is G1214W, a typical cone 6 transparent used by potters. It is fluxed by a boron sourcing frit. The glaze on the left is typical of what many use to achieve a matte. The recipe is:

Nepheline Syenite40.00
Dolomite15.00
Whiting10.00
Ball Clay20.00
China Clay10.00
Silica5.00

But this glaze is not flowing at all whereas the boron-fluxed glaze has run right to the bottom (and it is not even considered a highly fluid glaze). This simple comparison teaches us many things about glazes and even ourselves. Here are some of them.

Understanding your glazes is so much better, especially when it comes to dealing with their problems (and this one would have plenty!).

Related Information

The next time I buy a bunch of materials to test an undocumented online recipe slap me!

Look at recipes before wasting time and money on them. Are they serious? This is a cone 6 GLFL test to compare melt-flow between a matte recipe, found online at a respected website, and a well-fluxed glossy glaze we use often. Yes, it is matte. But why? Because it is not melted! Matte glazes used on functional surfaces need to melt well, they should flow like a glossy glaze. How does that happen? This recipe has 40% nepheline syenite. Plus lots of dolomite and calcium carbonate. These are powerful fluxes, but at cone 10, not cone 6! To melt a cone 6 glaze boron, zinc or lithia are needed. Boron is by far the most common and best general purpose melter for potters (it comes in frits and gerstley borate, colemanite or ulexite; industry uses more boron, zinc and lithia frits). The lesson: Look at recipes before trying them.

A functional matte cone 6 glaze should melt as well as a glossy

True functional mattes have fluid melts, like glossy glazes. They need this in order to develop a hard, non-scratching durable glass. The mechanism of the matte on the right is high Al2O3 (G1214Z), it is actually melting more than the glossy glaze on the left (G1214W).

Links

Articles A Low Cost Tester of Glaze Melt Fluidity
This device to measure glaze melt fluidity helps you better understand your glazes and materials and solve all sorts of problems.
Articles What Determines a Glaze's Firing Temperature?
By understanding how glazes melt and materials and chemistry interplay to determine behavior and temperature of melting and testing degree of melt you control the melting temperature of your glazes.
Articles Why Textbook Glazes Are So Difficult
The trade is glaze recipes has spawned generations of potters going up blind alleys trying recipes that don't work and living with ones that are much more trouble than they are worth. It is time to leave this behind and take control.
Articles Reducing the Firing Temperature of a Glaze From Cone 10 to 6
Moving a cone 10 high temperature glaze down to cone 5-6 can require major surgery on the recipe or the transplantation of the color and surface mechanisms into a similar cone 6 base glaze.
Articles Trafficking in Glaze Recipes
The trade is glaze recipes has spawned generations of potters going up blind alleys trying recipes that don't work and living with ones that are much more trouble than they are worth. It is time to leave this behind and take control.
Glossary Matte Glaze
Random material mixes that melt well overwhelmingly want to be glossy, creating a matte glaze that is also functional is not an easy task.
Glossary Glaze Recipes
Stop! Think! Do not get addicted to the trafficking in online glaze recipes. Learn how they work. Understand them. Then make your own or adjust/adapt what you find online.

By Tony Hansen


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