The title of this post has absolutely nothing to do with the contents. I just couldn't think of a catchy title and I'm watching Seinfeld re-runs. Maybe I should've called it Serenity Now........
Since my last post, I've fired my kiln twice and have garnered many, much informative information, yes I have.
As I mentioned before, I was hoping to find a firing method that would produce rich surfaces, with flashing and texture. I have 2 other potter friends who are interested in learning more about soda firing and were willing to help. (Julie and Rita.) That's us, pictured above, basking in the glow of my venturi burners. I'm holding a small, cardboard figure named "Flat Stanley" that arrived in the mail the day we fired. He was a kindergarten project for a friend's grand-daughter and was supposed to spend the day with me, so he "helped us" fire the kiln!
I'm going to share as much detail from our experience here as I can, because I was so thankful for the information we were able to gather on the internet and utilize in our firing! Even though experience is the best teacher, I hope this can at least give interested, inexperienced potters like myself a starting point. I had never ever fired a gas kiln before last fall!! So take my findings for what they're worth! (Liability disclaimer.)
We used a couple of books, Soda, Clay and Fire, by Gail Nichols and Soda Glazing by RuthAnne Tudball. We found our most helpful information on Emily Murphy's pottery blog. (Luckily we also love her work and the dynamite results she gets on her pottery!!) This particular page of her blog was chock full of information!
The first firing we mixed up a batch of Emily's soda mixture recipe and decided to introduce the whole batch. We weren't absolutely sure what size of a kiln this amount was intended for, probably larger than mine, but we thought it may also have been intended for a seasoned kiln. We decided to start with this amount and if the draw rings made it seem as if we didn't need to use it all, we could always stop. On the other hand, if it didn't seem like we were getting enough coverage we did have some extra dry ingredients mixed together, all we would need to do is add water.
For reference, my kiln is a sprung arch down draft with a hard-brick interior coated with ITC, soft brick exterior with ceramic fiber insulation on the roof. The interior dimensions are approx. a 36 inch cube, with a little extra at top for the arch. That's about 27 cubic feet of firing area. The stacking space is about 14 cubic feet. I have 2 burner ports in the back, one on each side, and a soda/salt port above each burner. I have 2 spies on each side near the top for cone viewing and draw rings, and a spy in the bottom front door. Before our first soda firing, I had done 2 salt firings in this kiln.
The soda mixture consisted of:
- 1.75 lbs. of soda ash
- 2.25 lbs. of soda bicarb (arm & hammer baking soda)
- 4 lbs. of whiting
I didn't do a body reduction, I think the atmosphere of the kiln was pretty neutral until we added the soda. We did some things in the first firing that we decided were incorrect, so we didn't do them in the 2nd firing.
We decided that besides causing a huge mess for us to clean up, introducing this extra salt was not giving us a true presentation of the soda vs.salt firing so we didn't do it in the second firing.
We read some interesting information in Gail Nichol's book about doing an hour or so worth of heat work after the last introduction of soda to enhance the results. She mentioned achieving different results depending on the kind of atmosphere the kiln was in during this time (oxidation vs. reduction) but we didn't quite understand her descriptions of exactly what kind of results each environment would produce. We decided to keep our first firing in a fairly oxidized state as a starting point.
As far as glazes, we used some celadon liners developed by June Perry She recommended various colorants to try. They were very consistent, and we especially liked one that had cobalt as a colorant. It was a deep, rich blue that complimented the dark brown of the phoenix quite well.
I had a turquoise oribe recipe I got out of John Britt's book. I had used it in my salt firings and wasn't pleased with the results, but thought my application might have been too thin. Tried it again, with a thicker application - - YUCK!! and DOUBLE YUCK!!! It came out a bright, gawdy, terrifying blue!! I am chucking that glaze and trying to find a new one. I want one with some iron and matte areas, that can blush red.
My Malcom's Shino worked well on cups and bowls, but on highly altered pieces that didn't have an exterior glaze, it seems to cause the pots to crack.
I had also mixed up a batch of Yellow Salt. I got the recipe when I was at the Odyssey Center in NC. It can come out nice when it gets hot enough, but it can also look dead. It's a yellow matte glaze that will get some speckling.
We also had a crackle shino, but it didn't seem to be thick enough. I also told Julie I thought she should apply it over a flashing slip to make it crackle more randomly.
After a couple of days spent cleaning shelves and chipping and grinding off the melted salt pots, we were ready to fire our second load. We mixed a few additional liner glazes. I had a recipe for The Glaze from Scott Shafer, and Julie found an Ash Celadon recipe in an article in Ceramics Monthly that was written by Tony Clennell.
We decided that we hadn't introduced enough soda in our first firing. We just didn't feel we were getting the juicy results we longed for and came to the conclusion that if a little is good, more must be better!!! We decided to introduce 1.5 times the amount we had used the first time. We also decided that we would put the kiln into a bit of reduction when we did the last hour of heat work.
Things were going relatively smoothly and we had added about 2 rounds of the soda mixture when Julie had a major epiphany. She asked me why we were turning the burners down and closing the damper when adding the mixture. I didn't have a good answer for that one. I thought that I had read it somewhere or heard a potter saying that was how they did it, but the more I thought about it, the more it seemed like that method was better suited for a salt-firing atmosphere. Since the soda mixture was heavier, and tended to drop down into the firebox, Julie's idea about keeping the burners on full blast and the damper opened seemed like it might give us better results. We searched both books and even got online to try to find specific information on this, but couldn't find anything! So, we decided to give it a try with the remainder of our soda introduction.
I think it made a huge and wonderful difference!! We achieved the results we were looking for! We got some beautiful directional flashing, and some dark, pebbly orange peel surfaces. The ash celadon glaze seems to have some promise as a liner also.
That's what it's all about, right?!