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stain problems on majolica

updated wed 24 jun 98

 

Helen Crowe on tue 23 jun 98

Thank Diana, Anne and Lorca for answering my stain/majolica problem. The
50/50 stain mix seems to melt completely but I shall certainly try more
frit. It looks like the base white glaze expands, breaking apart the stain
on the surface. Upon cooling and I cool slowly - dropping 50 degrees,
holding for 15 min., then ramping down 500 degrees before the program ends
- the stains remain broken and show white cracks through the colours. I got
a Bailey kiln vent and thought that the uneven heat was the problem but my
last firing was the same. Perhaps I should make my glaze from a lower
expansion frit? Am I cooling too slowly? I have not actually had such a
problem on my hand built work, but it is frustrating on these english
bisqued tiles. Some people prefer their 'perfection' so I'd like to make it
work. helen