Friday, May 21, 2010
Slumps, Bumps, Pits
My frost porcelain plate slumped and it has bumps. This was fired in the school kiln. I am told they fire to a hot cone 6. Debris fell in the glaze from somewhere and the plate slumped, not sure where it was located in the kiln. Oh there's a few pits in the glaze too. The companion to this plate is being fired elsewhere, the comparison should be interesting, stay tuned for that.
The good news is my experiment is a keeper. I put the black flower designs in slip on greenware, bisqued, then I sprinkled orange and green underglaze and then glazed with a clear over. I want the speckled colored glaze to be darker and more of them, but I like the layered look. I used a shiny clear, but I prefer my matt clear glaze much better than shiny. Next time it will be what I am striving for.
Here's a frost porcelain tray with a blue shino glaze from the school. Not a high fire shino that's for sure. I really miss high fire glazes. I didn't even notice the red color on the side till I took the photograph, looks like whoever picked up the piece must have gotten some other glaze on it. How do you prevent cross contamination of other glazes when loading, I am curious?
What cone should mid fire clay be fired to? The school fires to a hot 6; the woman who fired my last batch before I left California fired to a cone 6 with a 20 minute hold; the place I've taken my work to be fired this week fires to a cone 5 with a ten minute hold. Does it depend upon the clay, the glaze? There must be a rhyme or reason to firing cone 5/6.
Above is another glazing experiment being fired as we speak. In my packing I discovered a bunch of Mayco Jungle Gem glazes I had from bead making. I dabbed a bit over in various spots on this vase which is itself an experiment in embedded clay upon clay of the same type. I purposefully left some red clay showing. Some Mayco glazes will fire to cone 5/6; they have examples on their website of what they will look like fired.
I ordered my kiln; it should be here in about three weeks; more about that next time. Don't go away I have fifty more pieces coming up in the next week to show. Yes, fifty pieces, I can't even believe I made that many. Comments and suggestions are welcome.