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Archive for November, 2006

This is an image of my second kiln casting project right after it came out of the kiln. If you haven’t checked out the posting immediately prior to this one, I suggest doing so, as things will make a lot more sense. “Devesting” is the process of breaking apart the mold to reveal the sculpture underneath. They do the same thing with bronze casting. It’s the most exciting part because as each piece of the mold crumbles away it reveals the nearly finished sculpture below. It’s like opening presents on Christmas morning.

Here I’ve begun to saw into the crumbly mold material with a butter knife and then remove chuncks as they become loosened.

The mold-material is a mixture of plaster and silica. This was a hand built mold, which was applied in layers. The “face coat” is the coat that touches the artwork and is very fine. As we applied subsequent layers we added sand and grog(pulverized bits of fired clay) to add strength to the mold. The mold tends to break off in layers because it was built in layers.

Removing more of the mold, piece by piece. You don’t want to get too crazy at this stage, or you might scratch or break the glass underneath.

Here a large chunck of the mold has flaked off to reveal the front of the sculpture.

This is what the piece looks like after it has been devested.

During the mold-making process the mold often gets fine cracks as the plaster-silica dries. Once loaded into the kiln, the glass will fill those cracks as it fills the rest of the mold. This results in “flashing.” You can see the unwanted ribbons of glass around the edge of the piece. These will have to be cut off or ground down as part of the finishing process.

Scrubbing with a soft brush and water will remove the rest of the white, powdery mold residue.

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