Raku is a ceramic technique whereby clay pieces that have been fired once, are coated with unfired glazes. They are put in a raku kiln, heated, pulled out of the hot kiln with long tongs, and thrown in a pit or a can filled with organic matter --creating stunning glaze effects. Commercially manufactured raku kilns are expensive. A simple "top hat" gas-fired raku kiln can be constructed for far less money.
Take the lid off the trash can and lay the can on its side. Measure 2 inches below the top rim of the trash can and make a mark.
Measure the diameter of the end of the Venturi burner--a burner designed to burn gas inside a kiln. On a piece of paper draw a perfect circle 2 inches in diameter larger than the diameter of the burner. Cut out the circle.
Set the outside edge of the paper circle on the mark. Trace around the circle with a marker. Drill a hole in the center of the circle with an electric drill.
Put on gloves and safety glasses and use a tin snip to cut along the drawn line of the paper template.
Place the trash can lip on the floor. Draw a 4-inch hole in the center of the bottom of the can. Drill and cut out.
Drill and bolt on two, heavy-duty galvanized handles to the bottom outside edge of the trash can. Position them directly across from one another. These will be used to set the kiln over the pots to be fired and to retrieve the red-hot pottery during the firing.
Put on a filter mask and unroll some of the ceramic fiber blanket. Set the trash can lid lip down on the blanket and cut around it. This circle will insulate the bottom of the trash can where the 4-inch hole is cut. Place the cut-out circle of ceramic fiber blanket in the bottom of the trash can. Drill holes through trash can and secure CFB with ceramic buttons and nichrome wire--high fire wire.
Cut one strip of ceramic fiber blanket so when put inside the trash can on its edge, it covers every inch of the trash can wall. No metal should be showing except for a little at the inside top of the rim. Use ceramic buttons to secure the blanket to the walls of the trash can.
Cut out the ceramic fiber blanket where it's covering the holes that were cut from the trash can.
Set out eight double cement blocks on their sides, solid side up, where the kiln is to be fired. The ground surface must be level. Set two blocks end to end. Butt the next set of cement blocks up to the sides of the first two. Repeat for the remaining blocks.
Lay down a section of CFB on the cement block. Cut it 2 inches in diameter larger than the trash can lid.
Set a round kiln shelf on top of the CFB on the cement blocks. This is the inside base of the raku kiln. The kiln shelf should be smaller in diameter by 2 inches than the inside diameter of the lined trash can.
Set three to four kiln stilts on top of the shelf. Kiln stilts are ceramic spacers made from the same material as the kiln shelves. Place another kiln shelf on top of the spacers and set the raku-glazed pots on the shelf.
Turn the trash can rim down. Pick it up with another person by the two galvanized handles. Carefully lower it over the kiln shelves and the glazed pots.
Prop the Venturi burner up on a firebrick and center the tip in the middle of the round hole at the bottom of the trash can.
Connect the end of the hose leading from the burner to the high-pressure regulator on the propane gas tank.