Comment

Comment by Norm Stuart on February 2, 2015 at 12:57pm

Fast cooling being best for Zinc Crystalline glazes can be easily seen in this test tile:

fired to Cone 6 with a slow-cool with a few intricate crystals having formed;

then refired to Cone 04 without a slow cool and the entire glaze becomes crystallized without macrocrystals.

To live up to the name of Macrocrystalline Blue requires a third unspecified approach. But we don't have the kiln time to devote to that at our studio.

109.0%	Macrcrystalline Blue ^6
52.0%	Ferro Frit 3110
24.0%	Zinc Oxide
24.0%	Silica
2.0%	Lithium Carbonate
6.0%	Nickel Carbonate
1.0%	Red Iron Oxide

Comment by Jeff Poulter on February 2, 2015 at 11:20am

I had a load of ornaments come out on Sunday that had little to no crystals on them.  The only difference was that I fired the underglaze on them to ^5 to harden it a little so the moly glaze wouldn't eat it so bad, but I'm guessing that I didn't get enough moly glaze on them since the surface was less porous.  I'll re-heat them & re-dip them and fire them again to see how they come out.  jhp

Comment by Jeff Poulter on February 2, 2015 at 11:15am

Actually I am finding that its not long holds like for Zinc-crystalline.  It's all about the surface tension and keeping the moly inside the kiln to re-deposit back on the surface.  They seem to grow pretty fast.  Of course I haven't gotten them as big as zinc ones either.  jhp

Comment by Norm Stuart on January 30, 2015 at 7:14pm

You have to cool very slowly to get glaze defects that interesting.

Comment by kees staps on January 30, 2015 at 5:58pm

Very nice but how is it done please

Kees

Comment by Denice E. Demuth on November 21, 2013 at 6:03am

Very cool, I hope your underglaze tests work.  Denice

Comment by Jeff Poulter on November 20, 2013 at 4:48pm

New Moly test.  Finally got my spiny starfish crystals.  Now to change the underglaze & hope I can still keep them & make them "POP".....  jhp