Most quarters, now that we are in the new building on the south side of campus, we do a raku firing at the end of the quarter. This quarter we had to shovel first, so we wouldn't be standing in snow. During the firing, students asked me what the bucket of salt was for, thinking this might be related to a salt firing. The uninspiring answer was that the salt was for the ice on the ground. We had a lot of snow and ice this year.
|Extruder bowl by Malea Esqueda|
The raku firing process is lots of fun, but also fairly exhausting. We fired on Monday for the hand-builders and again on Tuesday for the throwers. It snowed on Tuesday morning, but not enough to stop us. About half the hand-builders were involved in the process on Monday. In fact, I was a little bit concerned about some of their pieces making it through the firing.
|Raku vase by Austin Peart|
The raku firing is a pretty intense process for the pots. We fire them up to temperature rapidly, then remove them, with tongs, when the glaze is molten. We take the pots out of the kiln and put them into a bucket of combustable materials (shredded paper, dry leaves). The materials light on fire and we close the top of the bucket to trap the smoke inside with the pot. As the pot cools, the exposed clay absorbs the smoke from the firing, turning any unglazed sections black.
|Raku bird jug by Malea Esqueda|
Some students took advantage of this effect and used wax to protect sections from glaze. Malea waxed the branches of the tree on her press-molded bird vase. Amber waxed what she says look like cow spots on her white vase and lines spiraling up her blue vase (the first image in this post). The contrast between the dry black clay and the white or blue glaze is striking.
|Raku cow vase by Amber Ryan|
Some of the students used copper based glazes. The copper in the glaze reacts differently when there is or is not available oxygen in the firing. With plenty of oxygen during the firing and/or after in the reduction bucket, the copper tends to turn green or blue. Without oxygen during the firing, the glaze tends to turn red. In the post firing reduction bucket a combination of reds and metallic coppers can show up.
|Faceted vase by Ruby Mayo|
We have several copper raku glazes in the studio. Two tend to melt to a glossy finish. On of those, the one we see in Amber's first piece tends to stay a teal blue with not much change to coppers and reds. The The other on Ruby's vase above goes green, red, blue, and metallic copper. Our third copper glaze does not melt to a shiny surface, instead it stays rough and even a bit crumbly. This is the glaze used on Ivy's small cups and lidded sugar dish below.
|Raku tea set by Ivy Shearer|
Several students chose to use a horse hair raku method during this firing. These pieces have no glaze on them. We fire them up with the other work and remove them when the other glazes are molten, but we don't put them in the post-firing reduction bucket. Instead, we take individual pieces of horse hair and apply them to the hot surface.
|Horse hair coil piece by Anjela Sevilla|
|horse hair extruder jug by Jennifer Martinez|
During this last firing I was amazed that Jennifer Martinez's extruded jug survived. The pots go through pretty serious heat shock as they are cooled from 1800 degrees Fahrenheit to the outside temperature (about 30-40 degrees on the days we were firing). This heat shock, as well as the fact that we have to move the hot pots using tongs, can cause the pots to crack during firing.
|Horse hair coil piece by Anjela Sevilla|
|Pit fired and painted coil piece by Raquelline Llaguno|
Raquelline Llaguno was the only student this quarter to choose to fire her work in a pit kiln. In fact, she was the only students in about the last 4 years to pit fire on campus. We set up a metal trash can with a few holes in it, loaded it up with shredded paper with her pot buried in the middle. Then we lit the paper on fire. It fired for several hours and created a variegated smoky effect on her burnished clay surface. Raqui then painted the yellow and red on the surface after the firing.
|Extruder bowl (top view) by Malea Esqueda|