Linda Arbuckle on tue 4 nov 97
Kenny,
In response to your majolica colorant problems and the rough and
metallic surfaces...
I assume you're using a white majolica glaze under your colors?
Sounds like you may be using your colorants too thick/concentrated on
the metallic surfaces. Copper overloaded can cause this, for example.
Majolica decorating colors are put on more like a wash than glaze
thickness.
The rough colors may be caused by using "body" stains, which are very
refractory (resistant to melting) colorants that are great for coloring
clays and slips, but often too refractory for majolica use, even with a
flux mixed in. Mason 6020 pink , titanium yellow stain, and one of the
lavender colors are such body stains.
You mentioned using 3 gerstley borate to one colorant, which is usually
fine. Some stains will work like this,, but some might need a touch more
flux or be applied thinner. But Vivid Blue and Alpine Rose are two such
stains. Mix 4 gerstley borate to one stain for those. Rutile and chrome
ditto. Something borderline refractory will be rough thick, but o.k.
thinner.
I'd suggest doing a test tile for reference where you do thin, "normal",
and thick application of the colorants on top of the base glaze to see
which ones would be likely to give you trouble thick.
Linda
Linda Arbuckle
Associate Professor, Graduate Coordinator
University of Florida, Box 115801, Gainesville, FL 32611-5801
e-mail:arbuck@ufl.edu (Note: this is a new e-mail address)
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