A glass furnace, just like induction furnaces are designed for melting metal, is a large oven like structure designed for melting glass in large quantities. Artists and workshop keepers use these machines when working with clear glass and colored glass as their material. There are two different types of furnaces you can make, you can make a pot shaped furnace and an oven shaped furnace. The oven shaped furnace is usually more dangerous to make and use as well, because of the size. The oven shaped furnaces also use more burners and give off more heat which makes them more dangerous. Just a single minor flaw in their construction can be dangerous. However the pot shaped glass furnaces are very easy to make and safe to use.
How to Make a Glass Furnace
Step 1 Getting your materials together (pot shaped furnace)
Most pot shaped furnaces are made from a 55 gallon drum. You will also need:
• sheet metal
• thick plywood
• a saber saw
• a welding torch
• power drill
The most important things you will need are vermiculite, castable refractory and water glass. These materials are used for heat proofing the furnace. Most pot shaped furnaces are considered a natural gas glass furnace because they normally use a natural gas as the heat source. Making a homemade glass furnace is not a hard job but you want make sure you are careful when making one. You will also need a burner and gas regulator along with some sheet metal screws and high heat paint to build your furnace.
Step 2 Constructing your glass furnace
The first thing you want to do when creating your furnace is cut the drum in half and then cover it with the high heat paint.
• Be sure to cover the interior and exterior heavily with thick paint.
• Now you want to mix the vermiculite and the water glass together equally until you get a gritty glue like substance.
• You want to pour about three inches into the bottom of the drum and let it harden before you do anything else.Furnace Cement
Step 3 The castable refractory
The next step is to mix up the castable refractory and pour about an inch into the bottom of the drum.
• The refractory is heat resistant cement like material. After everything has hardened, you want to drill a hole in the side of the drum level; with the castable refractory. This will create the drain as the glass melts.
• Next, when making home made glass furnaces, you will measure three inches down from the top of the drum and then put the sheet metal screws in a ring on the inside of the drum.
• Cut the sheet metal and plywood in a circle about an inch shorter than the barrel, so that it will fit inside.
• Once you have cut the metal and plywood; coat both of the materials heavily with the heat resistant paint. Then place the sheet metal inside the drum so that it sits on the screws and then pack more of the vermiculite and sheet glass on top of the sheet metal.
• As the vermiculite is drying; remove the sheet metal from the drum and place the plywood on top of it. This will be the cover for the furnace.
• The last steps you need to do are drill a hole into the side of the drum for the burner, and then weld the burner in place. The regulator should be in position behind the burner and attaches to the natural gas source.
After you have completed all these steps you should have a very nice home made glass furnace to work with.