Charcoal Foundry

Our team made two charcoal foundries out of the limited materials we could find in our homes and at a hardware store. Our goal was to make the foundries as cheaply as possible with readily available materials. We based it off of a mini backyard foundry built by a channel called the King of Random.

Foundries need to be insulated with a refractory material. We used a mixture of sand (21 Cups) and plaster of Paris (21 Cups), solidified with water (15 Cups).

The insulation was held together in a steel bucket (10 qt), and we inserted a plastic bucket (2.5 qt) into the partially-hardened plaster to create a cavity for the charcoal and the crucible. When mixing, we found that using your hands was much more effective than tools. While it is more messy, it is much easier to get to the clumps of sand and plaster that might not have been instatnly desolved into the water.

We also made plaster lids for further insulation, which we poured into buckets and removed when it was dry. Finally, we drilled a hole through the wall of the foundry to allow for a blower tube to supply oxygen to the charcoal. This was done roughly an hour after mixing the plaster, sand, and water to allow for the drilling to still be done with relative ease.

It is best to wait a few days to let the plaster fully set. Even then, it is possible that the foundry will have some residual moisture. After a few days, the foundry should be ready for use.

To melt aluminum, we surrounded a clay-graphite crucible with charcoal briquettes inside the insulation of the plaster. We inserted a tube into the hole in the side of the foundry and attached a hair drier to the end. With the hair drier on low, it made for the perfect oxygenation to keep the fuel burning.

We learned that it was important to use specifically charcoal briquettes, as coal is hard to light and lump charcoal burned away too quickly. In addition, it's helpful to use a "kindling" of sorts that can be easily heated and then incorporated into the charcoal. If need be, it can be useful to cut away some of the plaster if it will make room for larger pieces of charcoal. This allows the charcoal to light faster and stay hot for longer.

When it comes to the time to cast, be careful when pouring. If the metal moves easily when prodded with the tongs, it will most likely be ready to pour. The metal comes out quickly, so be sure to pour at a smaller angle to reduce the amount that comes out at once. But conversely, if you pour too slowly, the metal will begin to harden and oxidize and will not form to the mold as well. It can be very difficult to get this correct with smaller molds.