December 2019 Soda Firing

In December of 2019, I set out to fire my first soda kiln since graduating from the University of Wisconsin-River Falls in the spring of 2019. Since then, I had been primarily firing reduction cooled wood due to the low cost and accessibility. During that time, I had a lot of space to think about how I would like to continue pursuing soda firing from where I left off in the spring. I knew I wanted to pursue down-firing and was a little nervous to down-fire this kiln as I was not allowed to put any wood or charcoal into it - this is what I did all throughout undergrad. This was also a new style of kiln for me to be firing soda in - a downdraft, forced air burned, sprung arch kiln with an active damper. I knew that this firing would be totally different than my firings in undergrad and that this would be the beginning of a new way of firing.

Materials

• My Porcelaneous Stoneware and Continental Clay’s Woodfire Porcelain with 12 mesh brick grog wedged in.

• RF East Soda Flashing Slip from UWRF.

• RF Blue Celadon from UWRF.

• Basic salt/soda wadding.

Loading:

I loaded this kiln with the pots pretty close to each other so that they would manipulate the flame and create variation on the surfaces. For this I choose to load with a “loose height” with lots of variation in the height of the wares so that the shelves are not completely choked off from the atmosphere.

Results / Post Unloading Notes:

• There was an abundance of great carbon trapped surfaces, flashing and matte surfaces all the way through the kiln.

• The top of the kiln did not get a lot of atmosphere. There was not much carbon trapping and much quieter surfaces but some really interesting pinkish purples with the light soda flashing. This area of the kiln also had much brighter oranges and less flame trails than the rest of the kiln.

• Mostly everything below the top shelf of this firing had great carbon trapping and intense colors.

• The bottom shelf was the most intense with heavy carbon trapping. There was less purple here but more flame trails, halos, and reds. I would probably attribute this to the proximity of the exit flue - where everything in the kiln is traveled towards.

• The bottom shelf also had some blistering in the heavier reduced buildup of soda glaze - nothing a little sandpaper cannot fix!

• Throughout the kiln, there were some really interesting peach, pink, and yellow colors. It seems like these may have been produced by the reoxidation of the carbon trapping just beneath the surface through pinholes and cracks in the slip; but that it just a guess. This also seems to have happened where the slip was a little thicker and had pooled and dripped.

Next Time:

• Set shelves closer to the back wall of the kiln and an extra brick on the bag wall to promote the flame to move more towards the top of the kiln.

• Bring the kiln in and out of reduction during the down-firing to hopefully promote more flame trails and variation in color.

Summary:

All around I think that this firing was successful. I had a group of really interesting surfaces to continue pursuing and my anxieties about trying to down fire a forced air burner kiln in reduction were lifted. This firing will act as a bit of a base for my future firings in terms of surfaces that I am interested in and in firing schedule. I hope to increase the down-firing in length of time and fire to a lower temperature in future firings to see how that will change the surfaces and colors.