Soda Firing #3

---

The third firing of the soda kiln has certainly been the best so far, yet it didn't come without some hiccups. Temps were fairly even, colors and surfaces were new and exciting, but I didn't quite stick to my exact plan.

After thinking about the results of firing #2, I had planned on a few specific adjustments to the process. One major adjustment was going to be skipping body reduction entirely. The other major change was going to be a re-oxidation period after finishing the reduction-cooling cycle. The funny thing is–neither of these things quite turned into a reality. So why did I want to try these things, and why did I end up not doing them?

Footed Vase from Firing #3. 12" tall.

In the second firing, I noticed that my reduction was fairly light and yet there was still a lot of great red and purple color in my clay surfaces. While in India last year, I was researching reduction-cooling online and came across an essay by Owen Rye where he mused about what it might look like to fire a kiln in complete oxidation save a full reduction-cooling cycle to finish. It was this article that first got me thinking about the importance of body reduction in reduction-cooled firings, and after seeing the results of firing #2, it got me excited to try it out. (If you happen to know the specific article that I'm referencing, please shoot me a message so that I can provide a link!)

When it came time to pull the trigger and let that kiln climb sans-body redux, I...well...I sort of just chickened out. I started worrying too much about having a kiln full of anemic nightmares and that not slowing it down might result in another terribly uneven kiln. I decided that maybe I'll adjust my plan a little bit. I opted for an intentionally light body reduction rather than skipping it completely. I waited for cone 06 to soften, and entered body via a slight gas increase, and a reduction of air to my burners. No dramatic damper adjustments, no smokiness. Just a gentle lick of flame coming from the bottom peep, and a very subtle reduction smell when close to the kiln. I kept these settings for about 1.5 hours–until my 06 fell in the cooler area. This may seem like a long body reduction, but it was so light that it was barely perceptible.

Porcelain mug from Firing #3. 6" tall.

After my full down-firing cycle the clock read 4:41am. At this point, I was nodding off while listening to podcasts and trying to keep my stokes consistent. My intent was to turn a single burner back on, open the damper, and just hold temp steady around 1600F for about an hour. But, after 23 hours at the kiln, and a double work shift waiting to begin in t-minus 3 hours, I threw in the towel. I like to think that if I wasn't facing that long work day, that I would have followed through with the plan. But honestly I was so deliriously out of my mind, that I don't think it would have been very smart to do anyway.

The idea for the re-oxidation period came at the suggestion of Hideo Mabuchi, a potter and Professor of Applied Physics at Stanford University. Hideo has been scientifically studying the qualities and behaviors of iron in redcution-cooled atmospheres using the very powerful scientific equipment that he has at his fingertips through the university. His research has shown that in order to get the vibrant, cherry reds from a reduction-cooled firing, there must be a re-oxidation period. Usually this re-oxidation happens naturally during the cooling once the addition of fuel for the reduction-cooling has stopped. They found that when the re-oxidation happens is quite important, but something they hadn't tried yet was holding a kiln at the chosen re-oxidation temp to see what would happen. Next time...

---

Firing #3 Details:

• Preheat - 14 hrs (to 1292F)
• Active Firing - 17 hrs
• Downfire - 5.7 hrs (to 1612F)
• Soaked @ Cone 10 - 1 hour 50 min (in hottest spot)
• Finished @ Cone 11ish (in hottest spot)
• First Soda @ hour 12, 2158F (@ 1st cone 8 down)
  • 700g soda in 5.9lbs hot water
  • Stoking small wood intermittently
  • Took 12 minutes
  • Dropped 20 degrees
• Second Soda @ hour 15, 2192F (@ 1st cone 10 down)
  • 700g soda in 5.9lbs hot water
  • Stoking small wood intermittently
  • Took 7 minutes
  • Dropped 28 degrees
• 1 hour 35 min soak between 2nd soda and shutdown
• Shutdown, 2230F (Cone 10 top, cone 11 bottom)
  • Stoked 5 medium-sized pine pieces into firebox
  • Burners off.
  • Damper shut completely right away
  • 12 minutes before first downfire stoke @ 2192F (38 degree drop)
• Downfire (2192F - 1612F)
  • 2-3 small pieces of wood each time atmosphere cleared

---

Results:

Summary:

Directly from my notebook...
"This firing was pretty great. Managed to have a pretty even kiln, just about a cone off. The top shelf (cone 10) seems to be the money spot. There was some bloating in the ZMT-3 in the hot zone. RR-4 had some warpage on side-fired mugs at these temps as well. There are a few oxidized-looking pots, yet they still have good color. A few have that redux cherry red. Soda surfaces on the stonewares are beautifully silky matte and have a ton of color. RR-7 showing nice potential; a little more orangey than the ZMT-9. Wasn't able to do the reoxidation hold, but still would like to. Gotta get to temp faster but stay even! The RR-4 is still too waxy/fluxy. Need to reduce silica content. There is crazing in some of the thicker soda areas."

Well I am pretty happy with this firing, in spite of the deviations from the plan. As I noted above, and as you can see from the images, the range of color was quite broad, and appealing to my eye. I'm intrigued by the amount of color and variation within the soda itself. There are some pots that have sort of anemic looking bare clay areas beneath wad marks, yet still have complex colors in the soda. This gives me a little bit of an idea about what might have happened if I skipped the body reduction entirely. In light of this information, I've decided to go ahead and try a full, heavy body reduction in the next firing.

.

As I sit and write this, it has been one month and two weeks since unloading firing #3. The world has since changed. The global COVID-19 pandemic has altered the human way of life. There have been over 2.4 million confirmed cases worldwide, with over 169,000 deaths. The misinformation pandemic spreads even more quickly than the virus can. I've seen communities pull together to help protect one another. I've seen people compromise others' health and safety because they wanted a haircut. Strange times we live in. But so ripe for learning, and so ripe for change, if we truly pay attention and desire it. Here in Red Lodge, a local business has begun printing signs that read, "Together We Can Do This".  They now adorn the windows of just about every business in town.

They're right. We're all in this together, folks. Do what you can to keep yourself and your community safe. Always question what you hear. Seek the truth on your own. Don't accept everything you hear at face value. Even if it is from the lips of someone you admire. Together we can do this.

Thanks for reading, friends.

Harry