Saturday, June 11, 2011

Earthenware Kiln Firing

I know, I know, "what's Miss Stoneware looking at an earthenware kiln for?" While I may be impartial to stoneware, I also happen to like wood-fired earthenware, and this was more an adventure into the world of experimental archaeology! And, I like kilns.

I went to Old Salem yesterday and visited with the potter, Mike Fox, who interprets the Moravian pottery shop in the historic Single Brother's House. They built a kiln several years ago based on the archaeological excavations in Salem. They have figured out how to make it into a downdraft after a few trial runs. This firings is their first glost (or glaze) firing. Glost is an older term which you see historically used here in America, occasionally still used in England, and definitely in the records of 18th and 19th-century potteries in England. At least that is what I have gathered, correct me if I am wrong!

The front firebox had a grate inserted. I do have to wonder whether there was actually a patterned brick layout which formed a grate rather than a metal grate. Mo Hartley, the archaeologist at Old Salem told me that they found no evidence of a metal grate, but as Mike Fox pointed out, that could have been removed.

I did have to wonder whether the ware chamber was larger, and since an archaeological excavation usually reveals only the floor, I wonder whether the original kiln was not larger. It did not seem to hold that many pieces of pottery, which would surprise me to learn that the Moravians would fire so little so frequently in order to supply their market.
To start the kiln Mike was putting shovels of hot coals onto the grate. This is a good idea I think, as opposed to starting a fire in the kiln. This would distribute the heat better and create a more consistent temperature rise. Eventually he will add wood to the coals once it reaches a certain temperature. While it was in the hsitoric area, he did have some pyrometers hooked up so he could keep record of the temperature climbing. He said he made some cones of glaze -- not clay with glaze on it -- in order to see when the glaze fluxes and starts to melt. I will be very interested to follow up with him in order to see how that turned out.

I also took a moment to go back through the Art in Clay exhibition, which I highly recommend if you have a chance to see it before it leaves in August!

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