Here is an excerpt from Jill's Email
Thought you might like to see what I've done with the crackle glaze.
I did test tiles and found Janet de Boos glaze 47, a satin black to which I had added a little beech ash proved to be perfect for my purpose as I also wanted to create big blisters in grey and black. I did this by smearing the crackle back and forth with the brush over the black in a few places. The crackle on the top was very thick as was that surrounding the fissure in the centre.
I am experimenting with distorting the clay in the kiln by putting little blocks of kiln shelf under strategic places where I have induced cracks in the body clay. This is Abbotts Brick Red which I found readily cracks in normal throwing. I coiled the main pot then twisted it when almost leather hard. It was fired considerably hotter than recommended and I almost lost it when it slumped against another tall piece during a rather extended soak but both were able to be ground and recovered. Lots of fun.
One of the benefits of having a blog where I have been prepared to share information about the process of pottery, has been the letters that I have received "behind the scenes" from people like Jill. A few years ago I tested the DeBoos glaze that Jill mentioned, and it looked like a really nice glaze, but I had no immediate use for it. I more recently tested some crackle glazes, and I will, no doubt, use them one day, but not quite yet. I am familiar with the clay that Jill talks about (although I haven't personally experienced cracking problems with it). I use Abbots Brick Red myself when I am making planters and other earthenware pots. It was great to see Jill pull the black glaze, a crackle glaze, and the earthenware clay together and to use them in a way that was quite different to anything I would have done myself. I liked what she did with the firing, pushing the clay to a higher temperature than it was "supposed" to go to and deliberately stressing it by putting little blocks under the sculpture to make it twist when it was at high temperature. Such experiments are valuable ways of testing a material, and are also a good way of taking you out of a personal "comfort zone". The results may challenge beliefs about what clay and glaze should do, and what potters should do, and may open the mind and imagination to further possibilities.
I do like making mugs and bowls, and jugs and teapots, but it is good to keep open the possibility of doing other things with clay. Honestly, when you were a child and first played with nice squishy mud outside somewhere after it had rained, was your first thought, "Ahh, I must make a mug with this stuff!" Or did you enjoy the sticky feel of it between the fingers, and the splishy, splashy noises it would make as you stomped it with your feet? Did you try making monsters or animals, or did you draw in it with a stick?
I wish Jill well with her exhibition, and hope that her work inspires others to experiment, to take risks, and to rediscover imagination.
For those who might be interested....
DeBoos Glaze 47 Cone 3-5 (from Glazes for Australian Potters" J. DeBoos published in 1978 by Cassell Australia)
Nephaline syenite 75
Frit 3110 (4110) 15
Ball clay QA or C 5
Manganese dioxide 4
Red iron oxide 8
Cobalt carbonate 2
Oxidation: Smooth satin-matt black. Best at cone 4.
Reduction: Not suitable, as it becomes extremely metallic.