June Perry on mon 20 sep 99
Hi Everyone:
Well, I finally got my first soda firing in, using my ITC100 sprayed, old
fiber Geil kiln. In general I'm happy with the results, although I did turn
the kiln off too early, being concerned that the cones weren't reading
properly!
I had made little houses for the cones, but once I started spraying my soda
solution I wasn't confident that the reading was true, so I will be refiring
some pots where one of my liner glazes (Temple White) didn't mature. The
houses look great, by the way. They got the heaviest salting! I should take a
picture and put it up on my web site. Problem is I can't figure out how to
get a second page up with multiple pictures! Gotta hire some college whiz kid
to come out one day this fall and help me do that!
I got some cracking on a few pots and I don't know if it was from fast firing
in the beginning or the fact that I hit some of them directly with the
spraying. I know some pots that I went out of my way to zap good and they're
fine. I also played with a damper (in and out fully, about 3 times) every
time I did a cycle of spraying. My research showed that some people played
with the damper, someone else opened the damper when they sprayed; but the
article didn't say how open -- all the way, part way, etc. My damper setting
is usually open 2-3". Seems that opening it, is supposed to get the vapors
really moving through the kiln; but I need to know how much to open it.
I reduced from about 170025-1750 on (the kiln ran away! I had planned to
start at )cone 012 and even had a guard cone in there. I need a light in my
kiln shed! I thought I had only turned up the pressure a hair and checked it
in a half an hour and it had skyrocketed. I couldn't believe it! When we
moved we converted to natural gas and I changed the orifices. The only thing
I can think is that I turned it up more than a hair! . In any case, starting
later with the reduction, I got some great shinos and even got some nice
carbon trapping on one sake set. Good lesson learned on that one! I have
always started my reduction for shinos, at 012 or even earlier.
I only had about half my tests tiles and only two clay bars in there, so I
will be doing another firing in two weeks when we get back from a little
driving vacation to N.California gold country.
I do have a question about the salting procedure itself, though. Do you turn
your gas pressure down and how much, to spray your solution and do you open
the damper as mentioned above. If you open the damper, how much do you open
it?
I made a MAJOR goof. This one can go in the pottery archives of stupid
mistakes! I grabbed a bag of sea salt instead of using soda ash! My husband
said I did that because I kept interchanging the terms, soda firing salt
firing! He's probably right! In any case, I didn't get good deposit of salt,
naturally, using only about 3 lbs of salt with a pinch of borax! But the good
news is that my fiber kiln stood up pretty well with the ITC coating!
I have one area near a front port, where I had patched a bare area with new
fiber using sodium silicate to attach and then coated with the ITC. That
chunk fell out. I'm not sure if it was because the sodium silicate didn't
hold of the salt did something??? Another tiny area at the back wall, needs
to be filled in; but the 22 year old fiber kiln looks good! The ITC did it's
job! I also sprayed it on the silicon carbide shelves and they don't show any
deposit of the sodium. I had washed the alumina shelves with an alumina
hydrate/clay mix and that is flaking, so I think I will grind those down and
put ITC on everything!
This kiln load was mainly a lot of old bisque pots I had hanging around the
studio along with about a third of the test tiles I made up for the soda
firings. I still have all my claybodies and clay bars to test and the
leftover pots to be fired.
The Amador and Rods Bod came out pretty dark which I figured would happen. A
few porcelain mugs looks great -- just a bit underfired. Jim has taken
possession of one large mug that I faceted and incised -- flashing slip
outside with some other slip accents on parts and lined with Tenmoku. It's
definitely a guy kind of mug!
Some of the new claybodies I formulated along with some published recipes
show good promise -- nice honey/tan colors on some and good flashing on some
of the lighter bodies. The next firing the full claybody bars will give me a
better indication. Right now I'm just looking at some of the bodies on the
exposed part of the test tile.
I had a couple of porcelain vases with Vivikas copper barium on --YUK-- over
fired and boiled and red on one part of pots. I'll save that glaze for
oxidation firings.
The Tenmoku is a great liner glaze, but next time I won't put it on the lip
of the mugs. I didn't get full cone 10 on the bottom and the glaze still ran
off the lip. It's a shame, because it looks good. Maybe I'll try dipping the
lip separately with a thinner batch of the glaze.
I am so excited about this type of firing and I love the warmth of the
flashing slips and some of the clays. I had been using the same glazes,
basically for about 25 years, and it's so nice to be excited about the
process again!
Some of my old bisque pots were made of B-Mix and G-Mix from Georgies. I'll
refire them, but at first look they look pretty pasty as bodies -- unlike the
porcelain pieces which responded very well.
I want to publically thank Craig Martell for all his help with slips and
glazes and general support. It was his beautiful work that got me interested
in this process in the first place!
Time to water my plants and get to work. My husband keeps reminding me that
we're supposed to be retired! :-)
Warmest regards,
June
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