Most sources on the internet say you can’t bisque fire ceramic in an ordinary wood stove. But Sure it’s possible: Fire ceramic in a wood stove is like primitive pit firing in a metal box.
Fire ceramic in a wood stove
How to fire clay to ceramic in an ordinary wood stove:
First a word about safety: I’m not qualified to give fire-technical safety advice. I don’t know your woodstove or your pipe. The only thing I say here on this webpage; is that this is safe in my stove; I fired clay to ceramics in my stove more than 50 times.
The bottom line is still: Safety is your own responsibility.
Fire ceramic in a wood stove and this is how I burn:
A living room woodstove is not the best place to burn ceramics, but it does work! I have read several places that you don’t reach the temperature you need, and sure a pottery kiln burns much higher; bisque firing is typically about 1050 ℃, and for glaze-firing many burn much higher. An ordinary woodstove only reaches 3-400 ℃, many think you can’t burn ceramics in the woodstove. But the flames are more than hot enough, so between the logs, in the center of the fire, you can reach 6-700 ℃ on your goods. That’s how primitive pit-firing works, just make sure your goods are surrounded by flames. Clay sinters at 600 ℃, it sounds a lot. But I fire with a log or two more than I usually do, and easily reach 600 + ℃ on my goods, and I only fire for an hour or two longer than I normally would do when heating my house. Not unlike how I heat my house when I come home to a cold house on a winter day.
The clay body: If you put wet clay in the flames it will splinter: Water heats up to the boiling point, and the rapidly expanding steam can’t escape the clay body’s tight structure quickly enough, and the goods splinter apart (use safety googles). Clay needs to be bone dry before you burn it to clay. If clay feels cold when touched, it contains water, even if it feels dry it can contain water. A good practice is to worm up the dry clay on top of the oven the day before burning, then you know it’s dry. On top of my fireplace clay reaches 60 – 90 ℃.
Fire ceramic in a wood stove: When burning in the woodstove, it’s difficult to heat up as slowly as you would in an electrical kiln. Start the fire slowly with a small flame till you pass 100 ℃. Tough Raku clays and clay with a lot of chamottes are less fragile for quick temperature changes. It’s surprisingly difficult to make a small and steady fire and slowly raise the temperature in a household woodstove (here the fire and the clay are in the same chamber). For delicate ceramic, a firepot comes to the rescue. The firepot’s reduced fire space makes it easy to maintain a stable burning flame over a long time. The disadvantage of the firepot is it occupies valuable space, and it only has a mission in the first 1-2 hours of the burn cycles. Despite its pros and cons – a firepot is priceless when bisque-firing your most valuable goods.
Maximum temperature: You don’t need a lot of standing wood logs, high flames are not necessary. Lying logs burn slower, but they get the job done, just make sure you have enough embers. Calm flames from two or three logs will reach the desired temperature in some hours. One thing though; I have a clean-burning wood stove, meaning most of the fire is burned in the stove, and not sent up your pipe (as un-burned woodgas). Maybe this only works in clean-burning stoves? I don’t know. On the stove, it’s best if you can place a log over the ceramic or one on each side. Hold the maximum temperature for a little while so the ceramics get evenly heated (in these low temperatures it’s not uncommon to see only one side of the goods turned to ceramic, while the other still is clay). Do not place clay high up in your oven, it is hottest lying close to the bottom, but do not place flat goods directly on the bottom of the oven.
Read about the absolutely lowest of any low-fire flux here:
Fire ceramic in a wood stove: I only do bisque firing in my oven (glaze-fire is out of reach), and I can reach max temperature on the ceramic goods (6-700 ℃) in about 3-4 hours, let it cool down before the goods can be removed from the oven.
Why not build a real pottery kiln in your backyard?
After it cooled down it is time to find out if it really turned to ceramics. Tap the goods with your fingernail, a little pling sound is a good indication. The color would have changed slightly. But only the water-test gives the exact answer: Add some water to your goods, if it starts to colour off when you rub your finger against it or starts to feel slippery, it’s still just clay (then dry it well and burn it again).
