Tony Hansen on tue 27 mar 01
Iron red glazes run like crazy so although they look great it is often not
worth the trouble. But if they are not runny the rivulets, variegation and
crystalization don't happen. Hmmm.
However I've been working on a possible solution.
Use a less fluxed and therefore less fluid underbase version of the
glaze and a thin application of the fluid overtop. How? Use
a ceramic chemistry program to increase the silica/alumina in the
iron red base recipe (while maintaining their ratio). Be aggressive,
change it a lot. Then apply this less melting version in a thick
layer, then apply a thin layer of the original glaze. The result will
be the visual character of the thicker version without the
runniness. Of course, this means you need to have two glazes
and double dip, but it is worth it for iron reds. For this to work
your glaze cannot have excessive shrinkage during drying or it
will crack and peel after double dip. Here is an interesting
parallel: we found that Randy's Red (15% iron) gives the brighter
color associated with a very thick application and does not run
when applied in a thin layer over Ravenscrag slip on porcelain and
whiteware bodies.
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T o n y H a n s e n thansen@digitalfire.com
D I G I T A L F I R E C O R P O R A T I O N
http://digitalfire.com Calculation/Database Software for Ceramic Industry
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