|horse hair pots smoking in the YVCC kiln yard|
Yesterday it snowed and today was just COLD. I had forgotten that the heat isn't on in campus buildings over the weekend. Unfortunately we didn't have a bisque or glaze kiln loaded. An indoor firing might have helped keep us warm in the studio. The raku kiln is outside and, though warm itself, it didn't radiate enough heat to warm the entire kiln yard. I wore two sweatshirts over my two T-shirts and was still cold, even though I was also wearing a hat and gloves inside.
|students waiting in the cold for the kiln to be unloaded|
|smoke firing in barrel kilns|
|hair recently attached to a horse|
|horse hair and sugar pot (with paper reducing interior)|
We fired using the studio's permanent top-hat raku kiln. It has a hard brick base with a soft insulating firebrick interior. We put a kaolin fiber lined top on the kiln for firing, but the top is stored under cover the rest of the year.
|YVCC's top hat kiln and propane tank|
|kiln top being raised before first load|
We fire using my own venturi burner and a couple tanks of propane gas. The kiln yard does have an outside gas line, but when I first tried the burner and natural gas line at the school, I wasn't able to get enough pressure for the heat we needed. I have been meaning to try it again; I remember from a few years ago that the gas line was in some way affected by tearing down and replacing Glenn and Anthon Halls. I can't remember now if I tested the natural gas line before or after the buildings were replaced.
But the venturi burner and propane works well for now.
|frozen tank (on right)|
When I first got to campus we needed to set up the kiln. Today's special task was that we also had to remove the snow from the kiln shelves that cover the kiln base and keep the rain (or snow) and leaves out. The kiln yard had accumulated leaves along the wall and snow on top of these leaves so we also had to remove them.
The kiln top is then carried over to the base and attached to the cables and the counterweight is attached. The burner is attached to the propane and the kiln is loaded. This morning a few pieces were ready that had been glazed during the week.
|waiting to load kiln|
Other works that students glazed today were pre-heated in the bottom of an electric kiln so they wouldn't be wet when we loaded the second, third or fourth loads into the kiln. If the work is wet, especially if it is also thick, it can explode during the firing because the kiln is heated up so quickly. This time around we didn't have any work explode during the firing. No one dropped work either, as sometimes happens.
|cracked rim (probably due to heat shock)|
Once the kiln is loaded, the burner is lit and the kiln can be heated. The first firing takes about an hour because we need to heat up the whole kiln. This time around I tried to go slowly because the kiln base had been covered in snow and I was concerned that some moisture had gotten into the bricks of the kiln itself.
Once the work has heated up to the appropriate temperature (about 1750 degrees Fahrenheit or roughly cone 08), we turn off the burner, pull open the kiln top and remove the work from the kiln.
|kiln just opened (notice the bowl in back was knocked by the top of the kiln and has tipped over)|
|still glowing hot, pieces are removed from kiln|
|hot pot being placed in a reduction bucket|
|pieces cooling after reduction|
|placing hot pot in a reduction bucket|
|reduction bucket flaming|
|re-opening a bucket to add another hot piece|
|moving burner from frozen tank|
When we say "horse hair" we usually mean the surface treatment in which horse hair is used to create small areas or lines of reduction on the clay surface. The work is heated but not put in a post-firing reduction bucket. In our case, the work was not glazed either. The work is taken out of the kiln and horse hair (or steel wool, I've heard) is placed on the surface of the piece.
The hot pot burns the hair which leaves smoke residue on the surface of (or absorbed into) the clay. The coarse horse hair shrinks and twists as it burns, leaving an irregular bumpy line along the surface of the pot.
|teetering tower topped by a hot pot|
|yeah, let's put that hot pot closer to the ground|
|paper inside the pot (to blacken the interior)|
|throwing a pencil at your pot brings good luck|
|holding horse hair against hot pot|
|the pot on the right was coated in underglaze before firing|
|interior of copper glazed pot (with burnt paper scraps)|
|various copper glazed raku fired pieces|