Salt Firing fall '09

Thanks for this image, Grace.

The weekend salt firing was quick and sharp. Starting it at 7:00 pm Saturday and firing it off at 5:00 am Sunday reminded me of the firings we would do in Oklahoma during the summer. It would get so hot during the day we chose to fire through the night and finish at dawn to beat the heat.

The insulating fire brick (seen in the image) take a beating. We have been able to coat them on the inside (hot face) to keep them from deteriorating too rapidly. The spy holes are another story. Looks like a good spot for castable repair.

The anagama is still cooling some 3 days after...

Have been reading the latest edition of the Log Book . We knew Jack's article was going to be in it. I still find it hard to believe he lost interest in salt firing. The traditional approach to salt can be somewhat one dimensional, true, but vapor has so many variations from ∆ 03 up. It is so versatile. I have fired terra cotta at ∆ 03-3 with great results. In fact, I was looking for a similar surface to the Voulkos' platters while in grad school that lead me to experiment with low temperature vapor back then. Soldner used vapor in raku in the 1970's. There is so much to try. And Jack's excitement when holding pieces from our collection certainly gave you the sense he was still smitten. But as artists, we have to follow our gut as well as our head.

Speaking of raku- it too has endless possibilities if you get beyond the tired stuff of the past 2 decades. Going to commercial glazes is too easy. The "flash" factor is still alive and well unfortunately. Try using darker bodies and spraying on frits and clays and borax and lithium and ochre and on and on...

We are knee deep in a baroque fashion in American ceramics. Nothing wrong with that I suppose, but the band wagon is wide and deep. Always has been. I was a product of abstract expressionism (the last great dominant movement, I think- the post, post, post, modernist era is still up in the air, due to the need to label such movements immediately, sucking the oxygen out of the air) and the far eastern aesthetic which some today may find tired and lacking. But the subtle is permanent, flash is temporary.

Afterburn

After 39 1/2 hours we brought the wood firing to a close. We were able to soak for close to 7 hours allowing the back of the chamber to reach a solid ∆ 9. If there is one human trait that often trumps all others, it is patience. "Heat work," that critical, almost magical element is the reward for letting the kiln do its work without pushing and prodding.

It is particularly satisfying to show students this mystical process, after talking about it so much. The pyrometer and cones in the rear of the chamber confirmed our trust in the kiln and rewarded our commitment to continue stoking.

For our "soak" we decided to stoke to keep the rear at a steady 2100º F (not wanting the front to run away) and let the kiln do the rest. We finished stoking with pine bark for color. We shut it down after reaching cone 9 in the rear with the pyrometer still reading 2100 plus or minus.

Just as the lighting of a wood kiln is quiet and ceremonious only to the degree we want to confer, the end of a wood firing is equally so. Simply stop stoking and close up the kiln. No switches to turn or burners to shutter. The very instrument of all our constant and tiring attention simply winds itself down with no fanfare other than any we might wish to perform in front of it, assuming the energy is still there (and more likely to happen if given some thought before the lighting).

Once again we fired the salt kiln on the last night of the wood firing. Smoke and vapor everywhere. And it would not be complete without a visit from the UFD. They are always gracious and even curious at times. We are always very thankful they show even if we give them a heads up. You never know.

Fall Anagama Firing '09

Just a quick note- we are in the 31st hour of firing the anagama. We are at about 2100 degrees in the back of the chamber and climbing well. Our goal is to get above cone 8 in the back in the next few hours and continue the climb leading to a soak of 6- 10 hours.

More to come...

Upcoming Firings

We will be firing the wood kiln in a few weeks, loading early in the week of November 16. The plan is to start the firing on Thursday the 18th and fire till Sunday evening. We will be firing the salt kiln that weekend as well.

We hope to fire the wood kiln longer this time, getting more heat to the rear of the kiln and more "heat work" in general. When we visited SU last week they remarked how Jack had fired their anagama long and with little air. Makes sense- if you want to get heat to the rear, lengthen the flame. We have been making slight adjustments to that end as well.

SU's kiln has a very deep and tall firebox relative to the ware chamber. Never quite noticed that before. Although it is a hill climber (stepped chamber), the crown is level. Troy brought hardware for setting up a grate in the fire box. There are a number of pros and cons for this. In the case of the SU kiln, it seems that you would get more flame to the crown which would help draw heat up and over to the back of the chamber. You can get fewer ashes and coals as well. But patience is the key. A longer flame helps keep things even. Pots and bag wall placement/height matter as well. I am not sure about the stoking ports to the rear of the (SU) kiln. It seems they are so far back that you are feeding the stack, not the ware chamber. They are talking about creating an air port for the rear stoking port, but it still seems that you might be doing things a bit late in the chamber (ps- Henry Gernhardt, SU Prof., had suggested an air port in the rear when the kiln was first built- I defer to him!). Noborigamas don't have after burners. And the effects of a "check draft" need to be considered.

Feeding the stack has always been a question for me. A long flame does just that. But an even kiln is usually the goal. The trick is to strike a balance. The stack is a tool, not a chamber. But it is fun and dramatic to "candle" the top of the stack. There is so much to discuss here. We have a "secret chamber" between the main chamber and the stack which we have yet to experiment with. Part of the excitement is the variations in approach. Maybe someone has some ideas to bounce around.

We originally planned a grate on our kiln but opted out. We were tired and wanted to get on with it. We also knew of wood kilns without them that fired fine. I think it is something we will eventually try (our kiln chamber does not step up like SU's- our fire box is lower than the chamber; the crown is level). I do think the coal/ash amounts can be managed either way. One of the first things I learned years ago was not to be so efficient in pulling coals from the fire box. It is tempting- but you are losing valuable btu's.

Air is another issue. A wood kiln is the same as any fossil fuel kiln, but the reads are a bit different. For example, a lot of flame at the ports and damper means reduction in a gas or oil kiln, but not necessarily so with a wood kiln...

At SU they use the same phrase we do- "we are just learning about this kiln." Great fun.