Ceramic glaze covers three quite different products sold under similar names: ready-mixed dipping and brushing glazes, dry powdered glazes you mix with water, and the raw materials a glaze is made from. Knowing which of the three a listing is describing prevents most of the disappointment on this shelf.
Ready mixed, powdered, or raw materials
A ready-mixed glaze arrives wet in a tub, needs stirring and nothing else, and costs the most per litre. A powdered glaze is the same recipe dry, mixed with water to a bucket, and costs considerably less for the same coverage. Raw materials are the individual ingredients, weighed to a recipe of your own, and cost least of all while requiring scales, a respirator and testing.
What ceramic glaze paint means
Products labelled as glaze paint are usually brushing glazes: formulated with a suspending agent so they stay put under a brush and build in coats rather than running. They are the right choice for decorated work and for anyone without enough glaze to dip in. They are not paint in the household sense, and they still need a glaze firing to become glass.
Matching the glaze to the body
Every glaze has a firing range and it must overlap the body's. A stoneware glaze on an earthenware body simply will not melt; an earthenware glaze taken to stoneware temperature runs off the pot. Both facts are printed on the tub and on the clay, and checking them against each other takes ten seconds and prevents the most expensive mistakes in the kiln.
What it costs to glaze a pot
Less than most people expect. A bucket of dipping glaze covers a great deal of work and keeps indefinitely if it is covered and stirred, so the cost per pot falls steeply with use. Brushing glazes in small jars are far dearer per pot and are bought for colour variety rather than for volume, which is exactly the right way to use them.
Questions people ask about ceramic glaze
What is the difference between glaze and ceramic glaze paint?
Glaze paint is usually a brushing glaze, formulated to stay put under a brush. It is still a glaze and still needs firing.
Can I mix a powdered glaze myself?
Yes, and it is much cheaper than ready-mixed. Weigh in a ventilated space with a fitted respirator, because the powders are silica bearing.
Why did my glaze not melt?
Almost always a mismatch between the glaze's firing range and the temperature reached. Check the range on the tub against the cone you fired to.