Firebricks are used in the lining of fireplaces, kilns or furnaces. Firebricks are able to withstand heat up to about 1538 degrees C. Firebricks conduct heat extremely well, and are able to retain heat for quite some time. This ability to maintain a constant temperature and withstand extreme heat makes fire bricks an ideal structural component in the making of a perlite kiln, or a kiln used for any other purpose, such as pottery or cooking. Perlite, a volcanic glass, is used for construction, agriculture or filter aids.
Combine 50 per cent silica and 50 per cent fire clay in a large bowl. However many fire bricks you are making will determine the total quantity of silica and fire clay that you use. A pound of each part may yield eight 113gr. blocks. Mix the ingredients with your hands, or if you're using a larger quantity you can use your feet. Fire clay and silica can easily be found on the Internet or at your local home improvement store.
Mold the clay into appropriate sized bricks with your hands. This does not require a mould. Measuring the total area that will be used for the perlite kiln can offer some insight on how large you need to make the bricks. A common size for the brick would be 2-by-4-by-9 inches.
Place the bricks in a hot and dry area for two or three days to dry. Then flip the bricks over for another two or three days in order for the other side to dry. A conventional oven may be used, as well as an area next to a heater.
Bake the bricks in a kiln at 427 degrees C for two days in order to remove any excess moisture. All of the water must be absent before the next step. Do not rush this procedure or your bricks may fall apart when you try to remove them from the kiln.
Heat the kiln up to 0-3.889 degrees C for another two days. Then turn off the kiln and let the bricks cool, which should take about two to four days. Remove the bricks from the kiln and use them for your perlite kiln.