THE CRAFT OF FIRE

(cracked mold with a drop of bronze inside) For our first session this year (the weather has not been cooperative), our  plan was to make more bronze because we're almost out and we have lots of plaster molds (made over the winter) to fill. So we loaded the crucible with copper and tin, 90:10. in the hope of making bronze to cast it in our patiently-waiting molds. (NB: I realized later, though, that our 90:10 calculation wasn't quite right. We measured the 10% tin in relation to the amount of copper we had, but I think it should be in relation to the final amount of bronze we'll end up with. So we may in fact have been short about 6-7 grams of tin for a true 90-10 ratio. Would that be significant? Would it have helped bring the liquidus temperature lower?) Many of the molds were cracked, as you can see. It was more than likely that they got too hot too quickly in the kiln, during the wax burnout earlier this year. (The sprues are covered or stuffed to keep them clean before...

Our most recent session was the culmination of the whole process involved in casting a new object: new rubber silicon molds, wax patterns, plaster molds, wax burnout, bronze melting and finally, casting. And we have the wonderful feeling that we're learning. We wanted to cast a new pinecone and some acorns, too, and also a small medallion with the symbol of the School on it. These were the objects for which we needed entirely new rubber molds. The medallion was a real challenge because the engraving is very low-relief - we weren't at all sure if we could capture it first in rubber, then in wax, then in plaster, and finally in bronze. We made up our molds - medallion, pinecone, acorns, and a new salamander, too, because we had some extra material. And then we cast them using our newly made wax . We put two acorns together to improve our casting odds - maybe at least one would turn out. (image is there, but barely visible in wax) Next we made up the plaster molds, mixing sand and...