Firing a ceramic piece involves heating it to extremely high temperatures. Heating to such extreme levels removes the moisture from the clay and makes it hard and rather brittle. To control the temperature, ceramic artists and manufacturers commonly use a kiln equipped with a heating element and convenient controls. However, you can fire ceramics without a kiln using a large, heat-proof container such as a metal trash can. Firing ceramics this way is more primitive than using a kiln.
Things You'll Need
Metal trash can with lid
Drill and ¾-inch bit for drilling metal
Drill a ring of ¾-inch diameter holes around the bottom of a large metal trashcan. Place the holes 3 or 4 inches apart and 2 or 3 inches from the bottom of the can. Drill another set of holes around the top of the can. Space these holes 5 or 6 inches apart. Drill several other holes at random places around the can between the top and bottom rings of holes.
Put the trash can on a cleared, fireproof area such as a concrete slab or bare patch of ground. Spread a layer of sawdust in the bottom of the trash can 5 or 6 inches deep. Use clean sawdust from untreated wood.
Place your dry, unfired ceramics carefully in this bed of sawdust, leaving plenty of room between each piece and the sides of the trash can. Cover the ceramic pieces with several more inches of sawdust.
Continue layering unfired ceramic pieces and sawdust until you reach the top of the trash can. End with a layer of sawdust just below the holes around the top.
Place several sticks of kindling wood 10 or 12 inches long in a pyramid shape on top of the sawdust. Wad up some old newspaper, stuff it under the wood pyramid and light the newspaper. Let the fire become well established and cause the sawdust underneath to begin to smolder.
Place the metal lid on the trash can and let the sawdust smolder and smoke. Let it burn completely and then go out. This can take six hours or more.
Let the trash can cool for the same amount of time that the sawdust took to burn. The trash can must be completely cool before you open it. Therefore, from the time you light the fire, you must let the trashcan sit untouched for about 12 hours or more. Don't open or disturb the trash can in any way during this entire time and don't leave it unattended.
Take off the trash can lid and carefully lift out the pottery. It will be smoked and covered with ash.
Rinse each piece under plain water and scrub with a wire brush. Dry with a clean towel. Rub with beeswax to make it shine.
You may be able to get sawdust from a lumber mill or a woodworker’s shop; it must be made only of wood and should not have any chemicals in it such as from pressure treating.
The finished ceramics will be porous so they can't be used for liquids.
For ceramics with a smooth finish, burnish the clay before firing with the back of a spoon until it is shiny and even.
Do not leave a fire unattended. Always have a fire extinguisher handy during the entire firing process. Do not let children play near the trash can because the pottery can explode.
- Goshen College: Rework Clay, Dig Your Own Clay & Fire without a Kiln
- Fairfield County Public Schools: Firing Manual
- Ceramic Arts Daily: Clay and Atmosphere: A Guide to Ceramic Kilns and Firing Methods
- Homeschooling-Ideas.com: Smoke Firing in a Trash Can
- Homeschooling-Ideas.com: How to Pit Fire Clay