Posted 30 March 2013 - 04:16 AM
Posted 30 March 2013 - 10:16 AM
I recently used cobalt carbonate to fill a stamped motif on two small pieces made with white earthenware. I applied it when they were bone dry and cleaned up carefully (I thought) before bisquing in my electric kiln. There was cobalt residue on both pots which only showed after bisquing - very messy! image.jpg 1.23MB 93 downloads image.jpg 1004.14KB 73 downloads I know I could have had SOME on my fingers, but the cobalt appears to have spread during the firing. There was also some blue on another pot that was placed nearby in the kiln. I was able to clean them up, but it took some time! Any ideas as to how / why this happens and suggestions for preventing it another time.
As Marcia says, really strong oxide. I use it on bisque fired ware as a wash, and then sponge off the high, or even sand if I want a crisp image. This usually works much better than on greenware. You could also try underglazes instead of the cobalt on your greenware, a lot less intrusive.
Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . . http://picworkspottery.blogspot.com/
Posted 30 March 2013 - 11:15 AM
This photo is a very old mug done like this.
Posted 30 March 2013 - 12:02 PM
Contemporary Fine Colored Porcelain
TRY ... FAIL ... LEARN ... REPEAT
Posted 30 March 2013 - 05:14 PM
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