Most glaze recipes are measured by weight, in grams. The following is a general guide to help decide what size bucket to use.
500 grams = quart
2,000 grams = gallon
5,000 grams = 2.5 gallon
10,000 grams = 5 gallon
1. Weigh out material with a gram scale. Wear a respirator and gloves, and work in a well-ventilated area. Avoid breathing the dust of any dry glaze.
2. After each ingredient is weighed out, add dry material to water. The amount of water will vary depending on the material and the desired thickness of glaze. You may mix chemicals together first and then add water to desired consistency if you prefer.
4. Put liquid mix through a 60 or 80 mesh screen. Work the glaze through with a brush or your fingers. There is no need to push mixture through; too much pressure will wear out the screen.
5. Sieve again using the same screen, or one with a smaller mesh.
Since glaze materials are not soluble in water, all glazes have a tendency to settle. Every glaze must contain either ingredients or additives to reduce this problem.
For glazes that contain at least 15% clay (such as kaolin or ball clay) the addition of about 2% bentonite is usually sufficient. Be sure you mix the bentonite into the other dry ingredients before you add the glaze batch to water. Some potters use a product called Veegum Cer, added to the water.
For glazes with lower proportions of clay, other techniques are necessary. Potters can add 1 – 2% Epsom salts as a flocculant; others use products such as Flocs (in much smaller amounts); still others use muriatic acid (with care, of course).
Each potter must solve the problem of glaze settling in a way that is effective for each particular glaze. Failure to do so will result in a cement-like precipitate at the bottom of the glaze bucket.