Raku Firing During Class in the New Building

Today was our second class raku firing in our new building. We have a new counter lift system to lift the top-hat off the kiln base. The kiln base is all new bricks this year, though we haven't yet replaced the insulation in the top hat itself.

Wax on the bottoms of cool pieces loaded into a hot kiln starts to burn before the kiln is relit. (image by Dave R.)

Students in my functional pottery, intermediate and advanced wheel and independent study classes met starting today at 9am for the firing. We set up the kiln top on the new winch lift system and put in some glazed pieces.

A spot next to the top hat on the kiln helps dry a pot that was glazed after the deadline.

Our kiln runs on propane tanks and a Venturi burner. We heat the work up to about 1800 degrees in an hour or so. Then when the glaze is molten, the pots are lifted out of the kiln with tongs and placed in buckets of combustibles.

Hot pots coming out of the kiln look black on the outside because the matte glaze doesn't melt. 

Our new space is fairly small, but well protected from the wind and isolated from the main classroom by two sets of doors that help keep the smoke smell contained. We fired, maybe five or six loads of work today, including a few pieces that were refired after less nice results.

Hot pots put into the buckets instantly ignite the combustible materials inside. Students are ready to add more paper on top for even reduction.

We also had a few students try horse-hair raku, where the horse hair is applied to the unglazed surface of a hot pot. The horse hair burns black lines in place on the pot. I think next time we raku, I will prepare the students a little more clearly on how the horse hair process works before they are staring at a hot pot.

Applying horsehair to a small bowl like this takes precision and planning.

As for the glazed, pieces, after the pieces are placed into the reduction buckets filled with shredded paper or leaves, we place a lid on top and let the pieces cool and smoke. The lack of oxygen and the heavy smoke affects the surface of the glaze and the unglazed surfaces of the pots.

Reduction buckets are left to smoke and cool in between firings.

This time we used maple leaves and shredded paper for most pieces. The largest piece was so hot that we had trouble keeping the flames contained inside our reduction bucket. 

Pulling a fired pot out of a bucket sometimes causes the paper to relight.

The reduction atmosphere inside the kiln and in the reduction bucket gave us some pretty good results with at least one of our matte copper glazes. These glazes can look like they have oil spills or flamelike colors on their surfaces.

Our classroom's "Hawaiian Copper Blue"

The matte copper glazes can also be combined with clear gloss glazes to add some shine to the surface. 

This piece has been fired about four different time with glaze added at least twice.

Students who used wax resist to keep glaze from some surfaces of their pots ended up with deep black areas where the smoke was absorbed into the bare clay. 

The white side is a White Crackle Raku glaze with wax resist dots, the green is our classroom's "Texas Twister" copper glaze.

Our most unusual results came from a fairly thick coat of a glossy copper glaze with maple leaves heavily packed on top. 

This glaze benefited from heavy reduction with leaves. The underside is a brighter blue green color.