Recipes in Glazy


What is a Recipe?

Recipes are combinations of one or more ceramic materials. Recipes specify the proportion of one material to another. When mixed together, the recipe’s materials form a new type of material- a clay suitable for throwing, a beautiful, shiny glaze, or a colorful underglaze.

The recipe below is a classic recipe called “Leach 4321”. Leach 4321 is often used as an example because its recipe is very simple and it works well:

Leach 4321

Because the recipe lists the proportion of ingredients, you can think of the amounts as percentages. Leach 4321 is a recipe made up of:

  • 40% Potash Feldspar,
  • 30% Silica,
  • 20% Whiting, and
  • 10% Kaolin,

For a combined total of 100%.

It is not unusual to see recipes that do not total to 100. Often, recipes in workshops are written down as batches rather than 100% proportions. For example, Leach 4321 can also be written as:

  • 4000g Potash Feldspar,
  • 3000g Silica,
  • 2000g Whiting, and
  • 1000g Kaolin,

For a combined total of 10,000g.

It’s important to realize that this is the same recipe as listed above, just multiplied by 100 and specifying a unit of measurement. Potters often write down recipes in batch sizes that they work with to make mixing glazes easier. A batch size of 10,000g (like the one above) is often used when making up a large bucket of glaze or clay.

Note: All recipes are measured by weight, not volume!


batch, noun

  1. A quantity required for or produced as the result of one operation: made a batch of cookie dough; mixed a batch of cement. link

Because recipes list proportions of ingredients, no units of measurement are used. To make this recipe, you can measure in ounces or grams, even kilograms or tons!

For convenience ceramicists usually stick to the Metric System. Batches of recipes are measured in grams and kilograms. Small test batches are usually only 100 or 200 grams, while batches for daily studio use can be 10 or 20 kilograms.

More information about mixing up batches: Mixing Test Recipes

The Batch Calculator

Underneath each recipe listing is a Calculate Batch input box. After entering a number into this box, Glazy will calculate the total amount for each ingredient.

Here we calculate a batch size of 100:

And here we calculate a batch size of 200:

Base Recipes & Additional Ingredients

Recipes are often divided into two sections: the base recipe and additional ingredients.

Imagine a recipe for pizza. The base recipe would include the ingredients for making the dough and sauce, while toppings like mushrooms and sausage would be listed as additional ingredients.

For glaze recipes, the base recipe is usually a plain glaze without any color. Additional ingredients like colorants and opacifiers can be added to change the look and character of the original base recipe.

Below is the same Leach 4321 recipe, but with an additional ingredient of 1% Red Iron Oxide:

Leach 4321 Celadon

Notice that the name of this recipe has changed. Because this version includes 1% additive Red Iron Oxide, the type of glaze changes to a celadon.

Also notice that when calculating a batch, additional ingredients are added in addition to the batch amount. (The batch amount is actually the base batch amount.) So the total batch amount for this batch is 101, not 100.

Recipe Information

Each Recipe has descriptive information, or metadata, that describes it. In general, the more metadata is added to a recipe, the easier it is to categorize, compare, and search recipes.

Glazy uses highly structured data, meaning that instead of allowing users to define descriptive “tags” for recipes (like hashtags in Instagram), users are only allowed to select from a pre-defined, finite list of categories. Unfortunately, the names of these categories are currently only available in the English language. If you do not agree with a category, please contact Glazy and we can discuss changing it.

Type and Subtype

Defining a useful, universal taxonomy for glazes is very difficult. Some of the recipe types and subtypes in Glazy were originally imported from old databases, while other types were inspired by John Britt’s High-Fire Glazes.

Glazy’s recipe types are constantly being refined. If you have ideas to improve the system, please contact us.

Regardless of whether or not Glazy’s system of types is adequate, when creating a recipe please specify a type and subtype. If glazes are categorized more specifically with subtypes like “Blue Celadon”, “Black”, and “Clear” then it is much easier for both the Glazy software and users to navigate the recipes.


There are currently only three status levels:

  • Testing: A recipe that is not actively being used in the studio.
  • Production: A recipe that is actively used in the studio.
  • Discontinued: A recipe that is no longer used for some reason, for example an ingredient is no longer available or the glaze did not fit a clay body.

Only recipes with a status of Production are displayed in the default Glazy search page.


It can be useful to associate a recipe with a Country if the ingredients and firing are specific to a location. For example, many traditional Chinese materials are tied to specific mine and kiln locations.


.oxide-colors-R2O { color: #d32f2f; }
.oxide-colors-RO { color: #1976d2; }

.oxide-colors-Al2O3 { color: #388e3c; }
.oxide-colors-PbO { color: #388e3c; }
.oxide-colors-SnO2 { color: #388e3c; }

.oxide-colors-SiO2 { color: #7b1fa2; }
.oxide-colors-B2O3 { color: #7b1fa2; }

.oxide-colors-Li2O { color: #d32f2f; }
.oxide-colors-Na2O { color: #d32f2f; }
.oxide-colors-K2O { color: #d32f2f; }

.oxide-colors-BeO { color: #1976d2; }
.oxide-colors-MgO { color: #1976d2; }
.oxide-colors-CaO { color: #1976d2; }
.oxide-colors-SrO { color: #1976d2; }
.oxide-colors-BaO { color: #1976d2; }

.oxide-colors-TiO2 { color: #f57c00; }
.oxide-colors-ZrO { color: #f57c00; }
.oxide-colors-ZrO2 { color: #f57c00; }
.oxide-colors-V2O5 { color: #f57c00; }
.oxide-colors-Cr2O3 { color: #f57c00; }
.oxide-colors-MnO { color: #f57c00; }
.oxide-colors-MnO2 { color: #f57c00; }
.oxide-colors-FeO { color: #f57c00; }
.oxide-colors-Fe2O3 { color: #f57c00; }
.oxide-colors-CoO { color: #f57c00; }
.oxide-colors-NiO { color: #f57c00; }
.oxide-colors-CuO { color: #f57c00; }
.oxide-colors-Cu2O { color: #f57c00; }
.oxide-colors-CdO { color: #f57c00; }
.oxide-colors-ZnO { color: #f57c00; }

.oxide-colors-F { color: #757575; }

.oxide-colors-P2O5 { color: #0097a7; }

.oxide-colors-fill-R2O { fill: #d32f2f; }
.oxide-colors-fill-RO { fill: #1976d2; }

.oxide-colors-fill-Al2O3 { fill: #388e3c; }
.oxide-colors-fill-PbO { fill: #388e3c; }
.oxide-colors-fill-SnO2 { fill: #388e3c; }

.oxide-colors-fill-SiO2 { fill: #7b1fa2; }
.oxide-colors-fill-B2O3 { fill: #7b1fa2; }

.oxide-colors-fill-Li2O { fill: #d32f2f; }
.oxide-colors-fill-Na2O { fill: #d32f2f; }
.oxide-colors-fill-K2O { fill: #d32f2f; }

.oxide-colors-fill-BeO { fill: #1976d2; }
.oxide-colors-fill-MgO { fill: #1976d2; }
.oxide-colors-fill-CaO { fill: #1976d2; }
.oxide-colors-fill-SrO { fill: #1976d2; }
.oxide-colors-fill-BaO { fill: #1976d2; }

.oxide-colors-fill-TiO2 { fill: #f57c00; }
.oxide-colors-fill-ZrO { fill: #f57c00; }
.oxide-colors-fill-ZrO2 { fill: #f57c00; }
.oxide-colors-fill-V2O5 { fill: #f57c00; }
.oxide-colors-fill-Cr2O3 { fill: #f57c00; }
.oxide-colors-fill-MnO { fill: #f57c00; }
.oxide-colors-fill-MnO2 { fill: #f57c00; }
.oxide-colors-fill-FeO { fill: #f57c00; }
.oxide-colors-fill-Fe2O3 { fill: #f57c00; }
.oxide-colors-fill-CoO { fill: #f57c00; }
.oxide-colors-fill-NiO { fill: #f57c00; }
.oxide-colors-fill-CuO { fill: #f57c00; }
.oxide-colors-fill-Cu2O { fill: #f57c00; }
.oxide-colors-fill-CdO { fill: #f57c00; }
.oxide-colors-fill-ZnO { fill: #f57c00; }

.oxide-colors-fill-F { fill: #757575; }

.oxide-colors-fill-P2O5 { fill: #0097a7; }

The Unity Molecular Formula (UMF) Chart

See Also: Unity Molecular Formula (UMF)

Each Recipe page contains a Unity Molecular Formula (UMF) Chart.
This chart shows the recipes closest to the current recipe.
The current recipe is represented by a star symbol, while neighboring
recipes are represented by a circle.

R2O:RO Ratio

See Also: R2O:RO Ratio

The R2O:RO Ratio Scale shown in the Stull Chart.

The color of each recipe point denotes its R2O:RO ratio.
Recipes high in R2O are redder, while recipes low in
R2O are bluer.

Filtering the Chart

The chart can be filtered by using the form on the right. The recipe category can be changed (in the above screenshot, the category is Iron - Celadon - Blue), or the temperature can be filtered, or the axes of the graph can be modified.

The chart always loads as a plot of the oxides SiO2 and Al2O3

Because the Stull Chart is based on SiO2:Al2O3, it will disappear if you choose a different oxide pair.

Show Images

By clicking the “Show Images” checkbox you can display the thumbnail photos for each recipe in the graph. Please note that many recipes do not have photos and will only display as a greyed-out square.

Zooming in the chart

While the UMF Chart in the search can automatically be Pinched & Zoomed, the UMF Chart on the recipe page initially has Pinch & Zoom disabled in order to avoid accidental zooming.

Just click the “Allow Pinch & Drag Zoom” to start zooming.

Similar Base Recipes

If two recipes consist of the same base materials (not including additional materials) in the same amounts (within 1%), then they are considered similar.

  • Two Leach 4321 glazes (40% Feldspar, 30% Silica, 20% Whiting, 10% Kaolin) may be similar even if their additional oxides differ. For instance, Leach White is a 4321 glaze with added Zircopax, while Leach Celadon is a 4321 glaze with added iron. These two glazes are considered similar by Glazy.
  • A Leach 4321 glaze recipe with 40% Potash Feldspar is similar to the same glaze recipe with 40% Custer Feldspar because the materials or their parent materials are the same.
  • A Leach 4321 glaze recipe with 40% Potash Feldspar is not similar to the same glaze recipe with 40% Soda Feldspar because the materials (and their parent materials) are different.
  • A Leach 4321 glaze recipe with 39.5% Feldspar and a Leach 4321 glaze with 40% Feldspar are considered similar because the material amounts only vary by %1.

Similar Unity Formulas

Two recipes are considered to have similar unity formulas if their oxides do not differ more than .05 For this comparison, K2O and Na2O are combined (KNaO).

Note: Recipes that have similar unity formulas do not necessarily exhibit similar fired characterisitics.

Exporting Recipes

Recipes can be exported as a Recipe Card- an image containing the recipe photograph, name, and recipe details.

Recipes can be exported to your favorite glaze calculation software. Currently, only Insight and GlazeChem are supported, but hopefully more export formats will be added in the future.

To export a recipe, simply select “Export” from the menu on the recipe page. The Recipe Card image can be saved on your computer or shared with others online. The downloaded glaze calculation software text file can be imported into your program.


09/2016 Note: This is a new feature. If a recipe material is not listed, that material’s data has not yet been added. Some materials only have GHS ratings, while others only have HMIS ratings. Warnings differ between systems and countries. Glazy does not take any responsibility for accuracy of linked SDS information. Contact your ceramics supplier for safety information for your specific materials.

You must wear a NIOSH certified mask whenever mixing ceramic materials. All materials should be handled and fired in well-ventilated areas to avoid the risk of inhalation.

Lack of a warning does NOT mean that a material is safe.

From hazard warnings alone it is difficult to determine when and how a given material may be harmful. Some materials might be relatively safe to use when making glazes, but toxic when volatized during firing or leached from a non-durable fired glaze. Other materials might be relatively safe in a durable fired glaze, but extremely toxic in raw form in the studio. It is up to the individual to understand the risks of each material and take necessary precautions.

GHS Hazards

A more detailed chart is avialable on Wikipedia here.


Unstable explosives Explosives, divisions 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 Self-reactive substances and mixtures, types A, B Organic peroxides, types A, B


Flammable gases, category 1 Flammable aerosols, categories 1, 2 Flammable liquids, categories 1, 2, 3 Flammable solids, categories 1, 2 Self-reactive substances and mixtures, types B, C, D, E, F Pyrophoric liquids, category 1 Pyrophoric solids, category 1 Self-heating substances and mixtures, categories 1, 2 Substances and mixtures, which in contact with water, emit flammable gases, categories 1, 2, 3 Organic peroxides, types B, C, D, E, F


Oxidizing Oxidizing gases, category 1 Oxidizing liquids, categories 1, 2, 3 Oxidizing solids, categories 1, 2, 3

Compressed Gas

Compressed Gas Compressed gases Liquefied gases Refrigerated liquefied gases Dissolved gases


Corrosive Corrosive to metals, category 1


Acute toxicity (oral, dermal, inhalation), categories 1, 2, 3


Acute toxicity (oral, dermal, inhalation), category 4 Skin irritation, categories 2, 3 Eye irritation, category 2A Skin sensitization, category 1 Specific target organ toxicity following single exposure, category 3 Respiratory tract irritation Narcotic effects

Health Hazard

Respiratory sensitization, category 1 Germ cell mutagenicity, categories 1A, 1B, 2 Carcinogenicity, categories 1A, 1B, 2 Reproductive toxicity, categories 1A, 1B, 2 Specific target organ toxicity following single exposure, categories 1, 2 Specific target organ toxicity following repeated exposure, categories 1, 2 Aspiration hazard, categories 1, 2


Explosives, divisions 1.5, 1.6 Flammable gases, category 2 Self-reactive substances and mixtures, type G (see HAZMAT Class 4 Flammable solids) Organic peroxides, type G Skin corrosion, categories 1A, 1B, 1C Serious eye damage, category 1

Environmental Hazard

Acute hazards to the aquatic environment, category 1 Chronic hazards to the aquatic environment, categories 1, 2

More Information

More information about the Hazardous Materials Identification System (HMIS),
Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and GHS pictograms on Wikipedia.

Articles on Safety

I see the oxide section is still being built, but is there a reference for what the oxide color coding means?

I’m just now moving the help articles to this wiki. You can see coloring information here:

Question about how to tag firing atmosphere for your recipes. I’m looking to upload a bunch of recipes from my alma mater’s studio. They fire ^10 reduction, but the bottom of their kilns regularly fire oxidation, when the top fires reduction. Obviously the glazes I want to upload work in both atmospheres. So do I tag them all as Reduction & Neutral & Oxidation even if the test tile photo only shows the reduced tile? Or do I only tag them as Reduction? I have some recipes with clear differences between the reduced and oxidized tiles, but most are fairly uniform.

Yes, it’s a good question. Some glazes are only meant to be fired in a certain atmosphere. For example, Celadon glazes are usually meant to be light blue/green and only come out that color in reduction. In Oxidation, a Celadon glaze often comes out yellow. So the “Atmosphere” setting for Celadons should be set to “Reduction”. The same would go for other typically Reduction recipes like Copper Reds. But other glazes, like White glazes, might do well in either Reduction or Oxidation. (We’ve been thinking of removing “Neutral” as people often just specify Oxidation or Reduction.)

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