How to Fire Pottery without a Kiln
In recent years many people have started to pick up pottery from the comfort of their own homes. However, as a new potter, you’ll quickly realize that firing your pieces without a kiln is difficult.
Moreover, even a small pottery kiln is a big investment you are probably not willing to make as a beginner.
So let’s look at some other methods to firing pottery without a kiln.
Can you make pottery without a kiln?
Yes, there are several ways to make pottery even without a conventional pottery kiln. One method that people have used for centuries is pit firing, in which you build a large bonfire to heat your pots.
A kitchen oven can also be used to heat your pots. But if you are using regular clay, you won’t reach temperatures that are high enough to completely fire and vitrify the pots. So you’ll have to carefully choose to work with a type of clay that can be fired at low temperatures or use air-dry clay.
Pit firing pottery
Pit firing is a technique of firing clay that has been used for many years, in which the clay is heated in a hole or pit. This is an excellent method for producing unglazed, natural-looking pottery. However, it can also be utilized to glaze unsheathed pots.
This technique is just as much an art as a science. You’ll constantly need to experiment, observe the results, and tweak your approach. And every piece of pottery you fire this way will be a truly unique piece.
Pit firing safety
Since you will basically be building a big fire in your backyard, there are a few things to take into consideration.
The first thing to consider is whether you have enough space. You will need at least an area of 50 feet across, with nothing burnable in the way such as grass or weeds.
Secondly, you want to prepare plenty of water in case the fire gets out of hand. If you can catch it quickly, just a bucket of water might be sufficient. But a spray nozzle is a safer choice.
Finally, you’ll have to check if creating a fire is actually legal. Especially in large cities or during a drought, this is not always a given. If you’re not sure, you could try calling the local fire department. In some regions, you might be required to have a permit to start an open fire.
How do you pit fire pottery?
- Start off by digging a hole. The hole will need to be big enough to fit all your pieces of pottery. But you don’t want to make it any bigger than necessary, because you will need more wood to keep the fire going.
- Then start a little fire inside the pit by using some dry wood, twigs, planks, or anything you have available. But don’t place your pottery inside yet! The purpose of this small fire is to dry the ground. Because any moisture might lead to problems later on.
- Next, place your pots close to the fire but not inside the fire yet. This will allow the pots to slowly warm up. To speed up this process, you want to make sure that your pots have already been drying in the air for a few days. Do this for roughly an hour, and make sure to turn the pots halfway through.
- Once your fire has reduced to coals, rake it out to create an even layer with a bare spot in the middle for your pots. Give the pots roughly 30 more minutes to adjust to the higher temperatures.
- Now you can start adding wood to create a big bonfire. Make sure that the pots are completely covered by wood.
- Keep the fire going for as long as needed. You can estimate the temperature of the clay by the color it’s glowing in. A red color is roughly 900 C, yellow is around 1200 C, and white is normally above 1300 C. The temperature you need to reach to fire the clay depends on the type of clay you are using.
- Finally, you can let the fire burn out and recover your fired pots.
This might sound simple, but a lot of things can go wrong in the process. The most common problem is that people place the pots inside the fire too quickly.
If the clay goes from room temperature to several hundreds of degrees, it is likely to crack.
Pit firing vs kiln firing
There’s a reason why most pottery is fired in industrial kilns and not in open fires. A pit fire can’t reach high enough temperatures for vitrification. So the resulting pieces of pottery will still be porous and unsuitable for eating or drinking.
Moreover, during the pit firing process, your pots might crack from thermal shock because it’s difficult to control how quickly the pots will heat up. Whereas in an electric kiln you can accurately set the ramp rate.
The pit firing process is also much harder to control. It takes a lot of experience and knowledge to know exactly how much heat your pots will be exposed to and how long you need to keep the fire going.
Because the temperatures are so high, you also have to worry about burning yourself or starting a forest fire when the temperature rises too high near dry grass.
So, if at all possible, I strongly recommend using an electric kiln or firing service instead of pit firing.
Firing pottery in an oven
The kitchen oven is a more accessible way to fire your pots. It’s not a good method for firing ceramics on a big scale or in a commercial environment, but it’s an option for people who are just getting started with pottery.
In this case, you have to make sure to use clay that can be fired at a low temperature.
How to fire pottery in an oven
- Place your pieces in a preheated oven for one to three hours, depending on how thick the clay is. Heating the clay for too long might make the resulting pieces brittle, so don’t heat for too long.
- If your pots keep breaking, make sure the clay is completely dried out before heating. You can also heat the clay at a lower temperature for a while before raising the temperature to the maximum.
- Once you are done firing the clay, make sure to let it cool down slowly inside the oven. Opening the door and/or removing the pots too quickly might result in cracking.
Kitchen oven vs pottery kiln
The major downside is that kitchen ovens don’t reach very high temperatures. Most ovens only go up to 260 C, whereas most pottery kiln easily reaches temperatures above 1000 C.
As a result, you won’t be able to glaze or vitrify your pots. Which means you won’t be able to use your pots and plates for food. And most of your pots won’t be nearly as strong and durable as similar pots fired at higher temperatures.
Moreover, a lot of ovens only have one heating element, which means that all the heat is coming from one side. This results in a considerable temperature gradient in your oven and might fire your pots unevenly.
When at all possible, using a pottery kiln is preferred over using a kitchen oven. The resulting pots will be more durable, and you could also apply a glaze if necessary. The change of your pots breaking is also smaller since you can set the heating rate and the temperature inside the kiln is uniform.
There are a number of ways that you can fire pottery without using an industrial kiln. The most popular method is pit firing, but it’s not the best for people who want to use their pots and plates as dishes or drinkware because this process won’t vitrify your pots and will result in porous pieces.
If you’re just getting started with pottery and don’t mind having some cracks on your finished products, then consider trying out oven-firing methods like those described above.
An electric kiln might be preferable if you plan to produce large quantities of ceramics at once or work with glazes that require high temperatures. So if you are about your pottery, you want to invest in a pottery kiln sooner or later.