September 6, 2011 Part 3: The Process of Bronze – At the Foundry
Once the molds have been delivered to the foundry, the process begins in the wax room. Here, the molds are painted with wax, building up a thickness of 1/4″ – 3/8″ thick. The wax is removed from the mold, creating a wax duplicate of the original sculpture. To recap, we had the original sculpture (a positive), the rubber and plaster mold (a negative), now the wax is another positive. Wax sprues or channels are added to aide in casting so that the bronze will flow smoothly and will be removed once cast (shown in bright red wax below).
Various tools are used to attach the wax sprues to the wax figure.
Next stop, the ceramic room. The assemblage is dipped in a liquid ceramic slurry.
Sand is poured over the assemblage, starting with a very fine sand, picking up all of the super fine details.
The repetition of ceramic slurry coated in sand is repeated 10-14 times, building a ceramic shell around the wax piece, allowing it to dry between each coat. Below, wax pieces encased in ceramic are shown in various stages of ceramic shell. As the coats increase, the coarseness of the sand also increases. The ceramic shell is our next “negative” in the casting process. We went from positive (original sculpture), negative (rubber and plaster mold), positive (wax cast) and now negative with the ceramic mold.
The ceramic mold is a one-time use mold. For each casting in the edition, we’ll start back in the wax room with the artist’s rubber and plaster mold. Next it will be on to the foundry to heat it up, literally.
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