Glaze Recipe Calculator

In short A glaze recipe is a set of percentages of the DRY BASE, and the base is the part that sums to 100. Colourants are quoted on top of it — "plus 2% cobalt carbonate" means an addition, not a share — which is why a correctly written recipe totals more than 100% and why that is not a mistake. Batch a base of 1,000 g with 2% cobalt and you weigh out 1,000 g of base plus 20 g of cobalt for 1,020 g of dry material. THE WHOLE THING SCALES BECAUSE THE BASE WEIGHT CANCELS. Total dry weight divided by base weight is always 1 plus the colourant percentage over 100, whatever the recipe and whatever the batch. That is the entire reason glazes are written in percentages rather than grams: the same recipe works for a test tile and a bucket without a single number changing. Double the batch and every weight doubles while every percentage stays put. Two practical things the arithmetic will not do for you. Published recipes frequently do not sum to exactly 100 — a line gets dropped somewhere between a book and a forum post — so this page scales the base to whatever weight you asked for and tells you when the total was off, rather than silently correcting it. And water is never part of the recipe. Start somewhere near 85% of the dry weight and then adjust by specific gravity or by feel, because the right thickness depends on your bisque, your dipping time and what you are dipping. Two potters working from the identical recipe routinely get different results, and water is usually the reason. AND THE LARGEST LIMIT IS WORTH STATING PLAINLY: this page knows nothing about whether a glaze works. It cannot tell you about melt, fit, crazing, running, or food safety. It is a batching calculator, and it will weigh out a bad recipe perfectly.