5 Best Open Fire Pottery Techniques for Outdoor Pottery Firing
Who needs a kiln? People have been creating pottery for millennia and only more recently have kilns become popular, so get in touch with your ceramic heritage and do some outdoor pottery firing. I have been firing pottery without a kiln for over thirty years and this is my list of the top 5 ways to fire pottery outdoors so read on to see my favorite open fire pottery techniques.
The Smudge Fire
Quite possibly the most common open fire pottery technique of all and certainly among the simplest to perform. The smudge fire embraces and seeks out the dark and sooty marks that occur when the fire’s fuel comes in contact with the pots. This type of fire can be done either on the surface or in a pit although the pit method seems to be the most common technique. Anybody who has participated in the typical pottery “pit fire” in which bisque ware pottery is placed in a hole in the ground and firewood is stacked over the top and lit off, knows the drill for a smudge fire.
If the pottery is already bisque fired then it is even easier because you won’t have to worry as much about breakage or getting the fire hot enough. However, if you are making primitive pottery and are firing green ware then I offer the following precautions.
- Make sure the pottery is fully dry, see tips below under “what about breakage”.
- Create a bed of coals first, then place the pottery over the coals and stack firewood over it all. This will completely envelop the pots with fire ensuring a good firing temperature is reached.
Once the fire has started sit back and wait, let the fire burn all the way down to ash before you take the pottery out. If your pottery isn’t fully fired (rings like a bell) then you did not use enough firewood. Embrace the “fire clouds”, love the homemade look, fire smudged pottery!
The Polychrome Fire
While the smudged fire purposely puts the pottery in contact with the fuel because it wants the carbon stains. The polychrome open fire pottery technique separates the pottery from the fuel in order to create clean looking pots with bright, fully oxidized colors.
To fire this way follow these steps.
- Create a bed of coals
- Stack the pots on top of stones above the hot coals
- Place “cover sherds” pieces of broken pottery, loosely around and over the pottery to keep the firewood from coming in contact with any areas where you don’t want fire clouds and to keep hot coals from falling down between the stacked pots.
- Stack wood over and around the pottery and allow to burn down to ash.
There are two critical parts of this type of firing:
- Keeping the fuel from contacting the pots.
- Allowing plenty of air circulation around the pots.
There is a balance you must reach between these two elements because if you stack the pottery too tightly or layer on too many cover sherds that can limit the air circulation around the pots. This air movement is critical to getting a good oxidizing atmosphere which will produce bright colors.
I have produced an online class that teaches this type of firing in detail that is very affordable. Take a look at the details of this class by following this link.
The Sawdust Fire
The sawdust firing is dead simple and also lends itself to firing in an urban area (not much smoke, no high flames). This type of firing also embraces the fire clouds, seeking out the random organic designs left when the burning fuel is in close contact with the pottery. You will need a metal garbage can for this process and a quantity of clean, dry sawdust. Make sure none of the sawdust is from chemically treated wood because the smoke produced from that type of wood is toxic.
- Drill a few holes in the garbage can, especially towards the bottom, to allow oxygen to enter and feed the fire.
- Place a good layer of sawdust in the bottom of the can and pack down.
- Set the pots on top of this first layer. If you have a quantity of pots to fire you should alternate pots and sawdust so that the post aren’t all bunched up but each is separated from the others by a few inches of sawdust.
- Continue to fill and pack the can with sawdust. You dont have to fill the can all the way to the top but you should have a good 10 to 12 inches of sawdust above the highest pot in the firing. Pack the sawdust firmly around the pots and down.
- Light the sawdust on fire and place the lid on the can loosely to allow smoke to escape. You may need to relight if it does not get going good on your first try.
- Let it burn all the way down and get the post out when they are cool enough to handle.
The Smothered Fire
Unlike the polychrome fire that encourages oxygen to reach the pots, the smothered fire technique eliminates oxygen from the atmosphere. The goal is to keep the clay from oxidizing, leaving the slip a pale white color and keeping delicate organic paint from burning away entirely.
This method was used by the ancient Anasazi potters in the American Southwest to produce their stunning black on white pottery. They painted designs on their pottery with organic paint made from boiling down plants into a thick syrup. When this was painted on a white smectite clay slip and fired in a smothered fire it produced the classic Anasazi black on white pottery. The steps to fire pottery using this technique are as follows.
- Dig a pit in the ground and line with rocks.
- Build a fire in the pit to produce a layer of coals at the bottom.
- Place stones on the coals and stack the pottery on the stones. The tops of the pots should be just at ground level.
- Place cover sherds (broken pieces of pottery) over the pots to keep coals from the fire from falling down and contacting the pottery.
- Build a large fire over the top of the pit and light on fire.
- When the fire reaches maximum temperature, around the time the fuel is becoming coals, begin to smother the fire with the dirt from the pit.
- Keep pottery and fire covered with earth until it is cool enough to reach in and pull out the pottery with your hands, several hours at least.
Your success with this open fire pottery technique will depend largely on the timing of the smothering step. Too early and the pots will be dark and carbon stained, too late and the organic paint will begin to burn away. Keep practicing to get it right, trial and error is a great teacher. If you want more detailed instruction in this form of pottery firing check out the book Message From the High Desert which describes this technique in great detail. This link will take you to where it can be purchased on Amazon.
The Charcoal Briquette Fire
Tony Soares, a potter who lives in California, developed this type of firing and it is perfect if you live in a city and can’t build a raging bonfire in your back yard.
- Start by isolating the pottery from the fuel by placing them into some sort of metal container that is raised off the ground on bricks. Tony uses a piece of expanded mate bent into a circle but you could just as well use a galvanized tub purchased at a hardware store, just anything to keep the fuel from contacting the pottery. This container needs some kind of lid too, any old piece of tin or steel the right size could work.
- Next place charcoal briquettes under the container that the pots are in so there will be fire all around the pots when it is lit off.
- Next set clay bricks loosely around the outside of the pot container leaving a gap of about 4 inches between the bricks and the metal for fuel. The brick should come all the way to or slightly above the top of the metal container.
- Now fill the void with gap between the metal container and the brick with charcoal briquettes. The charcoal should come up to the top of the metal container and there should be a few on the lid as well.
- All you have to do now is light the briquettes and let it burn down.
Once you have a grasp of this system it is easy to do and can be done in almost any backyard as it doesn’t produce a lot of smoke or embers and the materials to do it are easily available at any hardware store.
Check out Tony’s video to see just how this system works.
What About Breakage?
While it is true that pottery fired outdoors breaks more often than pottery fired in a kiln, the breakage rate can be drastically reduced by taking certain precautions.
Most breakage in open outdoor pottery firings occurs because of either moisture in the clay or thermal shock. Both of these issues are easily dealt with.
- Thoroughly dry and pre-heat the pottery before firing to drive off any remaining moisture. I warm my pottery around the fire while developing a bed of coals before the firing starts but you can put them in your oven on low.
- Add extra temper or grog to your clay body to give more resistance to thermal shock. I usually use about 25% temper in my clay.
My YouTube channel has several videos demonstrating open fire pottery techniques, you can see them at this link. Also there are courses on this site that cover many aspects of traditional Southwest pottery from finding and processing wild clay to outdoor pottery firings and coil pottery making, check out those course at this link.