mel jacobson on thu 13 mar 08
Hi Mel,
I think you must have been off list when we talked of this a few weeks ago.
I have had a few problems with the new talc of choice Texas talc Pioneer
2882. It is in one of my clay bodies, and has changed the color and
refractory qualities of the clay. However, I have had great co-operation
from Laguna, both in California (thanks, Jon Pacini) and in Ohio (thanks
Matt Morris), and I have also found a couple of ways around some of my
problems in the interim.
Now, keep in mind I don't have the figures compiled from Jon Pacini's X-ray
diffraction tests in front of me now, but I will try to accurately report
them. Pioneer 2882 talc has a higher COE than Nytal. It also has been
tested and shrinks more as well as warps more than Nytal. It is also more
refractory.
Jon and Matt have recommended I replace the Pioneer 2882 in my clay body
with a western talc called Sierra Light, whose figures are more in keeping
with Nytal. As I write this, Matt in Ohio is mixing a sample batch of the
new talc clay for me and I will put it through it's paces in the studio
after I get back from my show next week.
I have found that increasing the fluxing power of my glazes just a bit gives
me more of the glaze results that I am after. That being said, I am also
experiencing radial cracking in plates and platters during drying, whereby
four or five cracks appear from the outside rim and work themselves into the
center, with the new Pioneer talc body. Increasing the compression on the
outside rim seems to help, but that is sometimes difficult to do on a wide
flange. I expect that this condition can be corrected by altering my
working methods over time, but it will no doubt result in a number of broken
pieces in the meanwhile.
Of course, the simple remedy would be to simply change clay bodies, and that
has been suggested to me by numerous potters. What I have done over the
past 20 years, however, is to calibrate my glazes to the two bodies I work
with, and every time I have experimented with new clay bodies every glaze I
use has appeared radically different than how I would like it to appear. To
a self-supporting potter, that kind of adjustment time results in serious
cash flow problems. I've chosen to stick with the devil I know than the one
I don't.
I am sending this to your personal email as I've had problems posting to
clayart via the archives. If this doesn't appear on clayart, could you
possibly post it for me?
Hope you are well,
Richard
Richard Aerni
http://www.richardaerni.com
http://richardaernipottery.etsy.com
146 Eastland Avenue
Rochester, NY 14618
585-473-5579
Studio
1115 East Main St. Suite 106
Rochester, NY 14609
585-429-0211
from minnetonka:
website http://www.visi.com/~melpots/
clayart site:
http://www.visi.com/~melpots/clayart.html
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