These were fired at cone 04. All three transparent glazes are on the same body (made from talc and ball clay). And fired at the same temperature - cone 04. Left to right: Amaco LG10, G3879C and Crysanthos SG213. We mix the middle one ourselves, from a recipe that employs a high percentage of Fusion Frit F-524. The first of four obvious benefits is evident: While frit F-524 is expensive, the glass it produces is more transparent and less iron-contaminated - so it transmits the whiter body color better. Second, the two commercial glazes are crazing. We fixed that using another expensive material, the super low expansion Ferro Frit 3249 (or its equivalent Fusion Frit F-69). Although containing significant MgO, that frit is an amazing melter even at this low temperature. Third, notice that the outer two mugs have micro-pinholes and surface defects that the middle one does not have. The reason for that is not obvious but it could be they have lower melt fluidity. The fourth benefit - the recipe can be adjusted to improve it. Yes, mixing your own glazes can really pay off in ware quality. At stoneware temperatures the opposite can also be achieved by mixing your own - creating glazes that use less expensive and more readily available materials.
Commercial hobby brushing glazes
These are an incredible benefit to pottery beginners and pure hobbyists. But they can also be an obstacle to progress and affordability as your skills improve.
Glaze Recipes: Formulate and Make Your Own Instead
The only way you will ever get the glaze you really need is to formulate your own. The longer you stay on the glaze recipe treadmill the more time you waste.