Pottery Glaze Mixing Calculator
Scale a dry glaze recipe to fill a bucket at a target specific gravity, with the water and the material breakdown.
A glaze recipe is written for 100 grams of dry material, but a bucket is filled by volume and set to a specific gravity rather than weighed out to a recipe. This calculator takes a recipe total, scales every material to the bucket size you want at the specific gravity you mix to, and reports the dry glaze, the water and the individual material weights. A 10 litre bucket at a specific gravity of 1.45 holds 14.5 kilograms of slurry and about 9.5 kilograms of dry materials.
At a glance
- What you enter
- Weight the recipe is written for, Bucket size to mix, Target specific gravity, Slurry from 100 g of dry glaze, Material 1 as a percentage of the recipe total, Material 2 as a percentage, Material 3 as a percentage, Material 4 as a percentage, Price of the dry glaze per kilogram, Surface to be glazed from this bucket
- What you get
- Weight of slurry in the bucket, Dry glaze to weigh out, Dry glaze in kilograms, Water to add, Water in kilograms, Dry glaze as a share of the slurry, Water as a share of the slurry, Scale factor for the recipe, Material 1 to weigh out, Material 2 to weigh out, Material 3 to weigh out, Material 4 to weigh out, Total of the material percentages entered, Dry glaze per litre of slurry, Cost of the dry glaze in the bucket, Glaze cost per square metre, Dry glaze per square metre
- Formula shown
- Yes, every step, right below your results.
- Cost and privacy
- Free, no account needed, and nothing you type is stored.
See worked examples ↓ Read the FAQ ↓ Share this calculator ↓
Results are estimates for general information only, always verify with a professional or official source before acting on them.
How to use the Pottery Glaze Mixing Calculator
- 1 Enter Weight the recipe is written for (g), The base weight of the recipe, which is usually 100 grams. Every material is scaled from this figure.
- 2 Enter Bucket size to mix (litres), The volume of glaze in the bucket, not the bucket capacity. Leave room for freeboard if the bucket is used for dipping.
- 3 Enter Target specific gravity, A dipping glaze is usually mixed to about 1.4 to 1.5, which is 1400 to 1500 grams per litre.
- 4 Enter Slurry from 100 g of dry glaze (ml), Most dry glazes make roughly 100 to 120 millilitres of slurry from 100 grams at a working consistency.
- 5 Enter Material 1 as a percentage of the recipe total (%), Enter the largest material first, which is usually the feldspar or the silica.
- 6 Enter Material 2 as a percentage (%), A second material, such as whiting or kaolin.
- 7 Enter Material 3 as a percentage (%), A third material, such as a frit or a clay.
- 8 Enter Material 4 as a percentage (%), A fourth material, such as an oxide or a colourant.
- 9 Enter Price of the dry glaze per kilogram, Optional. Used for the cost of one bucket.
- 10 Enter Surface to be glazed from this bucket (sq m), Used for the cost and material per square metre.
- 11 Press Calculate. You get Weight of slurry in the bucket, Dry glaze to weigh out, Dry glaze in kilograms, Water to add, Water in kilograms, Dry glaze as a share of the slurry, Water as a share of the slurry, Scale factor for the recipe, Material 1 to weigh out, Material 2 to weigh out, Material 3 to weigh out, Material 4 to weigh out, Total of the material percentages entered, Dry glaze per litre of slurry, Cost of the dry glaze in the bucket, Glaze cost per square metre, Dry glaze per square metre, and every intermediate step stays visible under "How is this calculated?"
- 12 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.
Worked examples
Real numbers run through this calculator. Open any example to load it into the form above and change it.
Filling a 10 litre bucket at 1.45
A 100 gram recipe at 40 percent feldspar, 25 percent silica, 15 percent whiting and 10 percent kaolin.
You enter
- Weight the recipe is written for
- 100 g
- Bucket size to mix
- 10 litres
- Target specific gravity
- 1.45
- Slurry from 100 g of dry glaze
- 110 ml
- Material 1 as a percentage of the recipe total
- 40%
- Material 2 as a percentage
- 25%
- Material 3 as a percentage
- 15%
- Material 4 as a percentage
- 10%
- Price of the dry glaze per kilogram
- $18.00
- Surface to be glazed from this bucket
- 4 sq m
You get
- Weight of slurry in the bucket
- 14,500.00 g
- Dry glaze to weigh out
- 6,904.76 g
- Dry glaze in kilograms
- 6.90 kg
- Water to add
- 7,595.24 g
- Water in kilograms
- 7.60 kg
- Dry glaze as a share of the slurry
- 47.6%
- Water as a share of the slurry
- 52.4%
- Scale factor for the recipe
- 69.05
- Material 1 to weigh out
- 2,761.90 g
- Material 2 to weigh out
- 1,726.19 g
- Material 3 to weigh out
- 1,035.71 g
- Material 4 to weigh out
- 690.48 g
- Total of the material percentages entered
- 90.0%
- Dry glaze per litre of slurry
- 0.69 kg
- Cost of the dry glaze in the bucket
- $124.29
- Glaze cost per square metre
- $31.07
- Dry glaze per square metre
- 1.73 kg
14.5 kilograms of slurry, about 6.9 kilograms of water and 7.59 kilograms of dry glaze, which is a scale factor of about 76. Material 1 is 3.03 kilograms and material 4 is 0.76 kilograms.
A small 5 litre test bucket at 1.5
The same recipe mixed thicker, for a glaze that needs to lay down more material.
You enter
- Weight the recipe is written for
- 100 g
- Bucket size to mix
- 5 litres
- Target specific gravity
- 1.50
- Slurry from 100 g of dry glaze
- 100 ml
- Material 1 as a percentage of the recipe total
- 40%
- Material 2 as a percentage
- 25%
- Material 3 as a percentage
- 15%
- Material 4 as a percentage
- 10%
- Price of the dry glaze per kilogram
- $18.00
- Surface to be glazed from this bucket
- 2 sq m
You get
- Weight of slurry in the bucket
- 7,500.00 g
- Dry glaze to weigh out
- 3,750.00 g
- Dry glaze in kilograms
- 3.75 kg
- Water to add
- 3,750.00 g
- Water in kilograms
- 3.75 kg
- Dry glaze as a share of the slurry
- 50.0%
- Water as a share of the slurry
- 50.0%
- Scale factor for the recipe
- 37.50
- Material 1 to weigh out
- 1,500.00 g
- Material 2 to weigh out
- 937.50 g
- Material 3 to weigh out
- 562.50 g
- Material 4 to weigh out
- 375.00 g
- Total of the material percentages entered
- 90.0%
- Dry glaze per litre of slurry
- 0.75 kg
- Cost of the dry glaze in the bucket
- $67.50
- Glaze cost per square metre
- $33.75
- Dry glaze per square metre
- 1.88 kg
7.5 kilograms of slurry at 1.5, so 3.75 kilograms of dry glaze and the same weight of water, with a scale factor of 37.5. The 100 millilitre yield gives a clean 1 kilogram of dry material per litre.
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Frequently asked questions
What specific gravity should a dipping glaze be?
Most dipping glazes are mixed to a specific gravity of about 1.4 to 1.5, which is 1400 to 1500 grams per litre. A litre of slurry at 1.45 weighs 1450 grams, so a 10 litre bucket holds 14.5 kilograms of slurry and about 9.5 kilograms of dry glaze once the water is accounted for. Mixing at 1.4 lays down visibly less material per dip than 1.5 with the same recipe, so check the figure rather than assuming it.
How much dry glaze makes a litre of dipping glaze?
Roughly 0.9 to 1.1 kilograms, or about 100 to 120 millilitres of slurry from each 100 grams of dry material. A 10 litre bucket at a specific gravity of 1.45 therefore takes about 9.5 kilograms of dry glaze, and the calculator reports both the dry weight per litre and what your yield figure implies so the two can be compared. A large gap usually means the specific gravity target or the mixing consistency is not what you think.
How do I scale a glaze recipe to a bigger bucket?
Work out the dry glaze the bucket needs, then divide that by the weight the recipe is written for. A 100 gram recipe scaled to 9.5 kilograms uses a factor of 95, so a material at 20 percent becomes 1.9 kilograms. The proportions never change, which is why scaling cannot spoil a recipe. Weigh the dry materials accurately, mix them dry first, then add water gradually and check the specific gravity rather than pouring in a measured volume.
Why does my glaze settle out or go hard in the bucket?
Because the heavy materials, and the frit and the silica in particular, sink faster than the clay and the whiting can hold them in suspension. A small amount of clay such as bentonite or kaolin in the recipe helps, and stirring before every use is normal even with a well behaved glaze. A bucket that has been standing for months may need the water poured off the top and the solids broken up and re-mixed, and the specific gravity checked again afterwards.
Are glaze materials hazardous to handle?
Yes. Glaze materials are fine powders and several of them, including crystalline silica, feldspar and various metal oxides, carry a respiratory hazard and some are toxic. Weighing dry material should be done with the extraction, the respiratory protection and the gloves set out on the supplier safety data sheet for each material, and the work area should be cleaned wet rather than swept. This tool does the arithmetic only: it gives no recipe, no substitution and no mixing or safety instruction, and it cannot tell you whether a fired glaze is suitable for food contact.