2020 Jerome Ceramic Artist Project Grant Blog

To begin with, I am going to take a step back to my first firings at NCC; I had three of them before beginning my grant research. I am sharing them because these firings’ research seamlessly transitions into the ones in which I was performing my grant research.

My first firing at NCC was in December of 2019. This was my first time ever firing an atmospheric kiln in doors which I was so very thankful for as it was now winter in Minnesota – brrrr. This was also my first time utilizing forced air burners and a kiln that I was not allowed to reduction cool with wood. I was a little nervous but fired anyways and utilized the burners to down-fire the kiln. The firing turned out far better than I had expected, and I found some new and exciting colors in my clay body and slip that I was not getting in my previous reduction cooled soda and wood firings. I knew that I was on to something with this style of cooling!

Notes:

• Sprayed 1,125 grams of soda ash into the kiln during three sessions beginning at ^9 in reduction.

• 30-minute soak after spraying.

• 3 hour down-firing to 1774°F in reduction.

My second firing at NCC was not as good; I had reoxidized the kiln too much during the down-firing and lost some of the exciting colors that I had previously seen. I was however left with some intense and bright flashing. This was one of those firings that I had learned a lot about what I am not going for! I had also stacked the bag walls and stack differently which pushed more of the atmosphere to the top of the kiln and help it fire more evenly which I had troubles with in my first firing at NCC.

Notes:

• Sprayed 1,125 grams of soda ash into the kiln during 3 sessions beginning at ^9 in reduction.

• One hour of soaking after spraying.

• 4.75 hour long down-firing to 1708°F in reduction.

Around the time of this firing, we were just getting word of COVID-19 here in the U.S. About a week after my March firing, the state of Minnesota had shut down. I was happy to have some fresh pots to sort through and some research to begin working on for this grant as I no longer had access to my studio or the soda kiln. I hunkered down safely at home and began working! I read Robert Tichane’s book Clay Bodies along with Gail Nichols’ Clay Soda and Fire for probably the 7th time…. After all my reading, I set out to begin formulating some new clay bodies. I was interested in looking into high alumina clay bodies; like Gail Nichols research and formulated 28 clay bodies ranging in a silica to alumina ratio of 2.6:1 – 3:1 using glazy.org. I also began working on this new website as a resource for others to learn about soda firing, my process and see my research. Something that is important to me is dissertation. I believe that there is a lack of information on soda firing and hope to help advance the general understanding of soda firing processes and materials interactions.

Moving on to May, I was lucky enough to have been back in the studio for some time to make pots and mix my new clay body tests which I then fired in June when I had kiln access again. I conducted this firing very similar to my previous firing except I reduced the kiln less during the end of the firing and down-firing and held the kiln at temperature for longer after spraying. I had also decided that I did not want to keep introducing steam into the kiln by spraying water every 15 minutes. I opted for soaking soft brick in water and introducing those into the spray ports every 45 minutes. I still saw some of the same effects that spraying the water in produced, just less intense. I had also learned a lot from my clay body tests! I was not very excited with the results, but they gave me good information on color and glaze accumulation. I had left the clay bodies too open by putting too much and too large of grog in them. With this information, I would reformulate a couple of the clay bodies that showed promising results to have a finer molochite filler in them. The clay bodies that particularly interested me and yielded some exciting results were ones that had 20-40% Gold Art in them. I believe that this supplied the clay bodies with enough iron to give color while was still fine enough to produce flame marks.

Notes:

• Sprayed 1,350 grams of soda into the kiln during two sessions around ^9 / ^10 in reduction.

• 45-minutes of soaking after spraying.

• 5 hour long down-firing to 1602°F in reduction with introduction of steam.

For my next firing in September, I continued to test my new clay bodies and used my usual porcelaneous stoneware and slip. This firing went pretty smoothly and for the down-firing, I decided to not introduce steam into the kiln. I was curious to see the difference again as I have become more comfortable on what I was going for with the down-firing. The lack of water reduction during this firing was certainly apparent and I did not see as intense of surfaces and saw less of the browns that I was talking about previously. This firing was still a good one but was a different direction in which I did not want to take at the moment. My new clay bodies resulted in some really wonderful surfaces and produced a more dynamic soda glaze with more depth to it. I would attribute this to a longer down-firing.

Notes:

• Sprayed 1,350 grams of soda ash into the kiln around ^9 and ^10 in reduction.

• About an hour of soaking after spraying soda into the kiln.

• About 6 hours of down-firing to 1591°F in reduction.

I was particularly excited for my next firing in October because my oxygen probe had just arrived from Econox in Switzerland. The folks at Econox were kind enough to give me an oxygen probe to test out as they did not have any information regarding the use of their probes in the soda kiln. I will send it back for analysis if or once it poops out. Part of this project grant was to utilize an oxygen probe to collect more data on the firings. The oxygen probe worked great and told me a lot of information as I fired up in temperature. It helped me realize that I have been firing in heavier reduction than needed, so I toned it down a bit which helped me fire the kiln more efficiently and quicker. However, the probe did not give me much information during the down-firing as it was placed in a less violent part of the kiln which did not receive much atmosphere.

After working with my new clay bodies I decided on one to reformulate further and mix a larger batch of; I would call this one T33! I also decided to try formulating some slips based on my clay body tests which would each be made up of 10-40 percent Gold Art. Some of these slips are less refractory than my normal slip that I use provided a surface richer in soda glaze accumulation.

Up until now I have typically down-fired down to 1600°F over the course of about 5 or 6 hours but this time I was able to go for about 7 hours. I also used wet soft brick once again to plug up the spray ports every 45 minutes. I feel like this firing was an accumulation of everything that I have learned throughout my time firing this kiln. I got a variety of surfaces that related to most of my previous firings. There was great carbon trapping, nice areas of depth in the soda glaze, intense flame marks and color, and the mysterious pinks and peachy colors. One new thing that I did notice from this firing was what I believe to be an iron crystalline structure which take form as small metallic spots among purples and deep reds. I would attribute most of these surface qualities to the longer cooling in reduction but it is hard for my to pinpoint at this time what mechanisms are causing what surfaces.

Notes:

• Sprayed 1,360 grams of soda ash into the kiln at about ^10 in reduction.

• About an hour and a half of soaking after spraying. There was much less soda glaze blistering because of this!

• 7 hours of down-firing to 1580°F in reduction with introduction of steam.

My December firing will be the last firing in this series of research for my Jerome Project Grant. Much like the last firing, I feel like this firing shows an accumulation of all my knowledge of firing this kiln. With the help of the oxygen probe again, I was able to fire this kiln in a more efficient atmosphere and much quicker. This allowed for more time to down-fire. I placed the oxygen probe in a different area of the kiln this time where I was hoping it would pick up more on the atmosphere during the down-firing. It was a little more reactive but due to the design of the kiln it has been very hard to create a homogenous atmosphere that reaches where I have put it. I did not get as great of a reading on the down-firing as I did on the up-firing again.

This firing left me with lots of dynamic surfaces and most pieces had areas of flashing and soda glaze.  My slip showed extraordinary variation with peachy tones in the thicker areas and more carbon trapped dark tones in the thinner areas. All around, my slip was a little too thick on my pieces leaving them to have more flashing than previous firings, but I am not complaining about that! I got some nice stony greys on my plates and there was not too much blistering in the soda glaze – less sanding!! Some pots had some interesting reds or yellows appear in the soda glaze matrix near rims or feet. This was my first time seeing this – it is almost like iron was caught in the soda glaze and crystalized.

Notes:

• Sprayed 1,360 grams of soda ash in around ^9 / ^10 in reduction.

• About and hour and 40 minutes of soaking after spraying.

• Just about 8 hours of down-firing to 1540°F in reduction with introduction of steam.

I have learned so much over the past year of firing this soda kiln and feel confident in my understanding of firing it to fulfil my research interests. It has been interesting switching from reduction cooling with wood to utilizing forced air burners for down-firing. It has made me think much more about what I am doing and be so much more intentional with my actions during the cooling. This research has brought to me so much good information on soda firing and has left me with an expanse of new questions to keep me busy for the foreseeable future.

Thank you for taking the time to read through my research. If you find anything odd, have questions or want to chat about soda firing please reach out to me!

-        Casey

Acknowledgements:

Many thanks to Northern Clay Center for the endless support in my artistic pursuits and research. Thank you to my partner, Laura Lusardi for supporting me personally, scientifically and artistically. She has helped me understand the physics of what I am doing and create graphs to contain my data. I am also thankful for my many conversations with Harry Hevenstein (https://www.harrylevensteinpottery.com/) and Isaac Howard (http://www.iehoward.com/) about soda firing technically and conceptually.