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terra sig questions/pyramid

updated tue 20 jan 04


Patty Alander on sun 18 jan 04

Terra sig has my head spinning lately! Got some amazingly colorful
pieces out of the pit fire - used the same batch of sig on each one -
yet it popped off of one piece and two have hairline crazing, five
others look fine. Black from smoke, I like the look of the hairline
crazing. I've done glaze tests where glaze pinged and popped off the
pot a week later, any chance of this happening with crazed terrra sig or
is it safe to sell them?

I used the terra sig at a specific gravity of 1.15, which I thought
would keep it attached, what other factors contribute to it popping off
the pot? I never had any problems when my pit fires were at a lower
temperature, this one went to 1400 F so I assume the higher heat
contributes to it. Is it also the volatile nature of a pit fire? If I
fired pots in an electric kiln would there be less chance of popping sig
at the same temperature?

The pots from this firing were 2-3 inches tall, and are easy to replace
- I want to fire some large ones and be confident I can count on the sig
- is this possible? Is there some criteria other than specific gravity
I should be looking at? Some people seem so cavalier about making and
using terra sig (and don't seem to have problems with it) and others are
so scientific about it! I've been trying both approaches and still
can't seem to get consistent results. I even tried Vince's, which seems
to work for everyone and I got some popping. I admire Vince and his
attention to detail, maybe I'll try his again - I must have done
something wrong. It's curious to me that Vince's is one of the few
recipes I've come across to use the very top layer - most others call
for the middle layer.

I'm grateful for Tony C's mention of the pyramid. I've been making pots
part time, off and on for 15 years and was getting sort of depressed
that they don't seem to be improving much lately. I used to get better
and better all the time! It made me realize I need to pay attention to
the details. This realization started with reading Clary Illian's
wonderful book. I want to make pots that sing, and to do that takes a
lot more concentration than I was giving it. I've never been happy with
the feet I make, so I spent a week exploring very different styles.
Now I'm working on the lips - I want lips that dance on top of the pot
- not tired looking ones that say whew, just made it with the last bit
of clay!

Thanks for all your help and inspiration!

feeding the right wolf in Grand Lake, CO

Marcia Selsor on mon 19 jan 04

Maybe the pot where the TS popped off was due to being on too thick. It
can also craze if too thick as well.
I agree with Vince to use the top level of TS. I always use that for the
final application when buffing. Some of my pots with TS are 8-10".
I make my TS according to the directions in the Kenny book "The complete
Book of Potterymaking" very old edition. He also says to use the top level.
Best wishes,