Glaze Batch Calculator
Scale a glaze recipe to any batch size, keeping colourant additions on top of the base where they belong.
Water is not part of the recipe — add it to the weighed dry materials until the glaze runs the way you want, and record the specific gravity rather than the volume. Nothing is uploaded.
Additions sit on top of the base, not inside it
A recipe's base is written as percentages summing to 100. Colourants and
opacifiers are listed separately and those are additions on top of that hundred, not
slices of it — so this recipe actually totals 110.
Which makes "a 1000 gram batch" ambiguous. Weighed the conventional way it is
1000 grams of base and the bucket holds
1100. Scaled so the bucket holds 1000,
every material comes out lighter and there is only
909 grams of base in it —
9% short.
| Material | Parts | 1000 g of base | 1000 g in the bucket |
|---|---|---|---|
| Custer feldspar | 40 | 400.0 g | 363.6 g |
| Silica | 25 | 250.0 g | 227.3 g |
| Whiting | 20 | 200.0 g | 181.8 g |
| EPK kaolin | 15 | 150.0 g | 136.4 g |
| Zircopax (addition) | +8 | 80.0 g | 72.7 g |
| Tin oxide (addition) | +2 | 20.0 g | 18.2 g |
| In the bucket | 110 | 1100 g | 1000 g |
The glaze itself is identical either way — both columns hold exactly the same proportions, and the fired result will not know which you used. What differs is how much of it there is, and the whole of the discrepancy is the 10 parts of additions. That matters when one bucket was scaled one way and the next was scaled the other, which is how a studio ends up with two batches of the same glaze that do not match in quantity.
Scaling behaves, once the base is the anchor
Anchored to the base, every line is simply its percentage of the batch — 40 parts of feldspar
in a 1000 gram batch is 400 grams, and doubling
the batch doubles every line. That is the reason the convention exists: it makes the recipe
readable straight off the page without arithmetic.
A recipe with no additions makes the two readings agree exactly, which is the mechanism
stated backwards — the gap between them is the additions and nothing else.
How to use
- Enter each material and its parts.
- Mark colourants and opacifiers as additions.
- Set the batch size you want.
- Choose whether that means base or bucket, and weigh out.
Frequently asked questions
Why does my recipe add up to more than 100?
Because the base sums to 100 and the colourants and opacifiers are added on top of it, not taken out of it. A base of 100 with 8% zircopax and 2% tin totals 110 — that is the convention, not an error in the recipe.
What does a 1000 gram batch mean?
Conventionally, 1000 grams of base — and the bucket then holds 1100. If instead you scale so the bucket holds 1000, every material comes out about 9% lighter and there is only 909 grams of base in it. Both are the same glaze; they are different amounts of it.
Does it matter which one I use?
Not to the fired result, since the proportions are identical either way. It matters when one bucket was scaled one way and the next the other, which is how a studio ends up with two batches of the same glaze that do not match in quantity.
Where does the water go?
Nowhere in the recipe. Weigh the dry materials, then add water until the glaze runs the way you want and record the specific gravity. Water is not a percentage of anything, which is why it never appears in a published recipe.
Why are colourants written separately?
So the base can be read and compared without them. Two glazes sharing a base are the same glaze in different colours, and writing the base as a clean 100 makes that visible at a glance — which is also why the parts are directly readable as grams in a 1000 gram batch.
Can I scale a recipe that does not sum to 100?
Yes. The calculator anchors on whatever the base actually sums to rather than assuming a hundred, so a recipe written in raw parts scales correctly without normalising it first.
Should I sieve the batch?
Yes, and it is the step most worth not skipping — 80 mesh twice is a common standard. It is not arithmetic, but no amount of accurate weighing survives a lump of unmixed colourant.
Does this send anything anywhere?
No. Every figure is computed in your browser, and nothing is uploaded or stored.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.