Monday, May 12, 2014

Record Kiln Firing

Rim of a flowerpot during the kiln firing
I am quite remorseful that I have not posted for several weeks, and will try to catch you up this week on the craziness that has recently (if not always) been my life.
An exciting recent event was a successful, record kiln firing yesterday at the farm! Not only did we accomplish a single firing (meaning no bisque-firing involved) in just over 12 hours, but almost all of the cones in the kiln reached cone 11.
Cones before they go in the kiln - each is made of clay that melts at different temperatures

Cones in action- the ones flattened have melted, telling me that the kiln has reached beyond
cone 10 (around 2300 Fahrenheit)

The cones give me a gauge for how hot the kiln is, as each cone melts at a different temperature. I usually shoot for cone 10, but reached 11 in nearly the entire kiln! My front left corner of the kiln is usually quite cool, but I have been adjusting the shelves to sit back from the wall and leaving more air space for the heat to move through.

Why, yes, that is clay on a baking sheet, ready to go in the oven!
Once again, I forgot to have draw rings or draw trials made up before we started the kiln. These get removed during the firing so I can tell whether the clay has matured and how far along my salting and slip color is. I ended up baking them in the oven the night before and putting them in the kiln in the morning. This seems to work well to get all of the moisture out of the rings and not have them explode when I put them in the kiln.

Side of a flowerpot
What was different for this firing was that I did a gas preheat with one tank in one firebox starting Saturday afternoon. Saturday evening I added a second gas tank (100 pound) burner to the second firebox. While the temperature at about 4:30 on Sunday morning was around 250 as it usually is, I think the bricks were heated up more, and that ultimately made the firing go faster. Because I foolishly made my kiln walls with two layers of hard brick, I spend more of the kiln firing just heating up the mass of brick. By using the gas preheat, this cut back on how long I would have to spend heating up the mass of brick.

Top of a hanging planter in the kiln
I started salting around 2200 degrees Fahrenheit, and did two rounds of salt about 30 minutes from one another. I did this both because I had a lot of people on hand at the time to accomplish this task, but also that I figured it might help to have the salt in place and get things good and melted for the rest of the firing. 
For a cute factor, a nest of baby wrens decided to try and take flight. They spent part of their day scaling various pieces of equipment opposite the kiln, including an old Farmall Cub tractor (photo above).

I'll have my fingers crossed for the next day with the hopes that everything turns out well! This coming Saturday is the Pottery Fair on the Square at Old Salem, so I hope to have some fresh flowerpots for the event!

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