Raku kiln, version 2.0

New Raku kiln

Bye, bye metal trash can, you've been replaced for a nicer, fancier model. Soft bricks rings to modulate the height according to pieces. Light top out of ceramic fiber for easy lifting, and a big flue to take small pieces through. And a huge space inside ! 23" diameter, great for large platters.

I took it out on a test drive last week. First ride was a saggar firing, baked potato style (see former post). Firing was done in an hour to 1400F, then I shut down the gas, plugged the holes and let it cool down naturally. It took about 4 hours to 250F, I unloaded the next morning. Aluminum foil had disintegrated to leave wonderful orange/red pots.

Square Bottles

Vase with australian fern imprint

Second ride was a regular Raku firing. I placed several pieces with crackle and copper glazes, as well as a Naked Raku piece. Again, the firing went well. I took out the Naked Raku piece at 1350F, after 45 mins, then I proceeded to increase the temperature to close to 1850F in another 20 mins or so. Venturi burner could definitely handle the kiln size, that was the true test. I am very happy with the results. Here are two of my signature Orb series.

Crackled Orb

Shadow Orb with pedestal

Ok, back to the studio ! I need more Raku pieces. I am all fired up ! :)

   

Making baked potatoes...

I don't remember who coined the term, but that's what Eduardo Lazo called it during his demo of ferric chloride saggar. It was a fun distraction from the Raku firings, and the processis is very simple and stepwise. Like a cooking recipe ! So let's make some baked potatoes, shall we ?

Eduardo making his baked potato

Ingredients:
1) bisqued pots, either burnished or with terra sigillata
2) solution of copper sulfate
3) solution of ferric chloride (Radioshack sells one)
4) spray adhesive
5) aluminum foil
6) organic/inorganic matter: horsehair, rock salt, steelwool, sugar, oxide powder, seeds, cut flowers,...whatever you feel like trying

Directions:
1) paint the pots with the copper sulfate solution
2) cut a piece of aluminum foil, big enough to wrap around your pot. Make a ball then gently flatten it back. The purpose is to crinkle it so it creates air pockets around the pot.
3) spray the adhesive lightly on one face of the foil and add the organic/inroganic matter of choice, in any pattern you want. The adhesive will keep most of it in place.
4) paint the pot generously with ferric chloride and wrap it with the foil, like a baked potato. That's your saggar.
5) Fire in a gas kiln, between 1000F to 1500F in 1 to 2 hours. Both the firing time and the firing temperature can affect the colorations.
6) Cool slowly in the kiln to let the colors develop, overnight being optimum.
7) Sponge the ashes off the cold pots and let them dry for two days to let the colors settle. Then wax/treat the pots. Renaissance wax is the best for high-end waxing. For a matte finish, use a light dusting with a matte acrylic spray then wax.

At the workshop, because of time constraints, Eduardo opted for a speed firing (1350F in 1h, cooling to 200F in 3h), and frankly we had some good results. But take a peek for yourself, that's what I brought back home.