Reid Harvey on sat 5 dec 98
I received the following from Donovan Palmquist and I've got to confess
I should have spotted sooner a small problem with the Ceramic Industry
Donovan Palmquist wrote:
I believe that the recipes given for stains/underglazes are not meant to
used directly as stains or underglazes. These recipes need to be mixed,
calcined or fired to a certain temp. and ground before they can be used
a colorant. If one were to add these mixtures to a glaze as listed they
would not give the effect of a stain in a glaze.
Normally, materials like borax, a standard frit material, are put into
useful form (ie. as a frit) in the way Donovan has said. Also, some of
the materials are specified as calcined. For several recipes, though,
this treatment may not be needed. I'm going to look again.