Tuesday, February 22, 2011

Isn't spraying fun ?!!

Hazmat Face
Last day of the workshop was ferric chloride day, or FeCl3 for the chemist in you. Eduardo Lazo was leading the charge. On the first day of the workshop, we all glazed a piece with a low-fire glossy clear glaze and they were fired overnight.
First thing on Sunday morning, all the pieces were loaded into the Raku kiln. Firing was slow, about 2 hours, up to glaze maturity. When it was about time to stop the firing, the "sprayers" had to suit up appropriately to handle the corrosive ferric chloride solution. In my case, double layers of gloves (nitrile gloves, heat-resistant gloves), a respirator and sunglasses.
The hot piece was taken out of the kiln and placed on a soft block on top of a banding wheel. The "sprayer", placed upwind (IMPORTANT FOR SAFETY), started applying the solution holding the sprayer upright, while slowly rotating the piece.

The ferric chloride gradually colored the outside layer of the glaze a yellow/orange color. The hotter the ware the darker the color. In my case I waited about 30 seconds before starting spraying, resulting in an orange coloration. Once a metallic luster appears, spraying is done.

The piece is then transfered to a reduction chamber. I prepared mine by lining sides and bottom with newspaper and adding a handful of wood shavings on the bottom. Once the piece was placed in the chamber, I added some more wood shavings in the inside of the pot for some good smoking of the unglazed inside. Because the piece had cooled off considerably during the spraying, I had to start the flames by fanning the chamber vigorously. Once the flames start to consumme the combustibles, time to close the chamber for some good ol' smoking.

Once the piece was mostly cool, it was cleaned up with a soft brush and water to remove the ashes. Beautiful !!!

The final piece

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