Charles Moore on fri 27 dec 02
Over the past couple of weeks there have been a number of postings about the
possibility of producing a clear matt glaze. Quite by chance, a year or two
ago, I tried James Chappell's Semi-Gloss (SG-7) because I wanted a clear
glaze that was not too shiny and would allow colored engobe decoration to
show through the glaze. I tried the glaze (below), which Chappell calls
"semi-gloss," but which I found to be more a "soft matt." It reminds of the
old Rookwood "vellum." It is very soft in appearance and designs show
through quite clearly.
CHAPPELL'S CLEAR SEMI-GLOSS ^5 (SG-7) P. 178
Kona F-4 feldspar 45.7
Gerstley Borate (GB) 12.9
I used it over blue and brown underglazes and engobes, which I wanted to
show through clearly. It worked beautifully.
When Alisa Clausen (from Denmark) tested it at my suggestion, she found that
some of her underglaze colors (not engobes) were not always true to color.
Presently, I am studying Insight's glaze calculation program. When I learn
to substitute for Gerstley Borate, I may post this recipe again.