Well school has ended and I think I’m getting a mercy B in the class. It’s a pity, I love making metal sculptures. It’s so much fun to pour metal and the results are impressive. Unfortunately crutches, knee injuries, and power tools don’t mix. But I got a taste for metal and eagerly await the fall semester. And I got a chance to see different kinds of metal getting poured. Aluminum is gray, Bronze is gold, and Iron is white. Between Bob and I, we got some great pictures of pouring metal.
The process starts with a mold. We use the lost wax method which begins with a sculpture made of wax. There are many ways to make this wax mold including sculpting directly with the wax or creating a mold and pouring wax. Once you have the wax piece, it gets contained into a mold made from either a plaster and sand (the big round cylinders) or ceramic shell (in the oven).
The metal gets heated in a crucible for either aluminum or bronze. In the two foundry schools I’ve seen (Palomar College and the Fallbrook Academy of Sculpture), these crucibles go into an oven in the ground. I’m sure there is a more formal name, but I don’t know it. In the first picture (Fallbrook), you can see some raw bronze metal waiting to be melted. In the second picture (Palomar), aluminum blocks are beside the furnace hole.
Iron is special, it requires much higher temperatures. In Fallbrook, they had a large cylinder with gas flames underneath. Two views of this iron melting tank are shown — daytime before they starting the melt, and a night shot where the Iron and Raw COKE (high quality anthracite coal) were mixed together to create enough heat for melting the metal. They spent all day extracting iron from old bathtubs, sinks, and brakes, you can see the piles in the first photo.
After the metal reaches temperature, it becomes a viscous fluid. Aluminum and Bronze are melted in a crucible. Iron is melted in a large tank and flows into the crucible. The ceramic molds are heated to 1800 degrees and placed into sand. Then the crew, dressed in leather and special heat protection suits, start pouring metal into the molds. It’s very exciting to watch the metal. The pictures tell the story better than I can. But look at the different colors coming from the crucibles. You can see the difference between aluminum (gray), bronze (gold), and iron (white). The heat pulsates outward and tension rises. If anything goes wrong, someone could get hurt very badly.
In this last picture, something happened and the metal exploded into flames. There are crew members with buckets of sand. They quickly shovel sand on the molds and flame. But everyone gets excited, its events like this that make metal pouring dangerous.
After the metal gets poured, the molds need to cool down. Then it’s like an easter egg, you get to crack the shell and see what’s inside. Usually people have trouble waiting to do this, so they crack them while metal is still hot. Below are several pictures showing first the aluminum in the mold, after being taken out from the mold, and sawing off the sprue.
Here’s what hot bronze in ceramic shell looks like
And here are some pictures of finished sculptures. You’ve seen them in older posts, but they help finish this story.