Over IAP, I took a metal sculpture class. I've always wanted to try metal casting, and finishing a metal sculpture was a really satisfying experience. I started off by making a model out of wax. As a material, wax is basically adult play-doh. It holds its structure well, but is not difficult mold or add texture.
After the wax model was finished, we had to add sprues for the molten metal to fill the mold better to prevent voids from forming. The wax model was cast into a cylinder of refractory cement to make a mold. After the refractory cement had set, the wax was baked out of the mold, and the mold was fired in a kiln. Finally, molten bronze was poured into the mold, and after it cooled, the mold was broken apart to reveal a semi-finished tree.
After being freed from the mold, the tree required some post-processing. The model was sandblasted to remove especially tenacious mold material and oxidation. All of the sprues and feeders had to be cut off, and any metal that filled air bubbles in the mold had to be removed. Sanding and filing was required to clean up the areas where the sprues were removed, and the tree was finally done. In order to finish the tree, I plan on letting it naturally oxidize and occasionally polishing the surface to allow the oxidation to highlight the textured surface.
