A furnace or foundry is simply an enclosed, highly insulated container than is used to heat materials. This furnace will use a super-material known as Starlite, which can effectively insulate temperatures of up to 10,000C for minutes on end. This material can be placed on your hand, and will remain cool with a blowtorch aimed on the other side.
The material works by creating a carbon foam on its surface. Carbon is so heat resistant that it scientifically cannot melt, so it is the perfect insulator in a foam form. This foam can be made by heating a specific mix that creates carbon dioxide when heated.
The first part of this project will be like baking, but each of the ingredients is vital to create the desired carbon foam.
To make Starlite, combine 2 parts of flour, 1 part corn starch, 1 part baking powder and 1 part sugar in a bowl. TO make the furnace below, make enough to cover the inside of the can and its lid. I used 250g of putty (80g of flour, 40g others, 50g water)
Then slowly add 1.5 parts water while kneading until you make a putty-like dough. When this dough is heated it will release carbon dioxide while forming a layer of carbon on its surface.
Next, we have to make the furnace can. Choose a preferably large can. I used a can of spinach leaves. because of its wide diameter.
Next, strip all flammable materials off the can and clean it out, making sure it is completely dry.
Next, bend a corner of the lid up, to allow you to lift the lid off easily with a pair of pliers. Then drill three small holes as an exhaust. It can be noted that the lid is purely optional, and marginally improves performance.
Next, drill a hole slightly larger than the nozzle of your blowtorch near the bottom of the can. Leave space for insulation on the bottom.
Thinly line the inside of the can and lid evenly with the Starlite. Make sure there aren't any holes, and use a screwdriver to make sure that no holes are obstructed.
Now, simply place the nozzle of your blowtorch into the furnace, and you are done!
