How to Pit Fire Pottery

Pottery is one of the oldest art forms in the world, and one that has changed little in the last millennium. Creating a hand thrown or hand built pot is basically done the same way it was in the Middle ages, and before. What has changed is how we fire, or cook, that pottery. Today artist and craftsmen use electric or gas kilns, a special kind of oven designed for the firing of pottery. What did people use before that?

It is no accident that when we put a pot in a kiln we say that we are 'firing' our pottery.  Fire was what was used before electricity and natural gas, and not that long ago.   Today people still use a fire method of firing pottery in what is called 'raku' pottery.  This method adds carbon into the glazes and smoky pattern can appear on the clay.

Here in the United States Native Americans used a pit fire to harden clay for use.  Here are the basic steps that I have used before, as it was taught to me.

  • Find a good hill of clay, the natural earth that pots are made out of.  Dig a hole into the clay, straight down about three to four feet deep, creating some 'steps' or shelves as you go.  It will be hard to dig if it is dry.  You can run a hose onto the area to make the digging easier.   The hole should be a couple of feet wide on and long, but it doesn't have to be square.  Make your pit as big as you have pottery to fill it, as the kiln needs to be full to fire properly.

  • Clear the brush and grass from around the pit for several feet.  Nothing should be near it that will catch fire.

  • Use a large piece of tin or corrugated metal roofing to cover the pit.  In ancient times large pieces of broken pottery would have been carefully placed over the pit once it was loaded, but this can be tedious and not necessary.

  • Gather lots of hard wood pieces, that are very dry and seasoned.  You can also use cow or buffalo dung that is very dry.  Which ever you use, it needs to burn hot and long.  Osage orange, oak and black thorn locust are woods that would be found near where I live.  Lots of small pieces as well as large, so kindling or wood chips and saw dust are good.

  • Make sure the pit is lined with clay.  Add some to the walls and shelves if there are spots of bare earth. 

  • Fill the pit with dry wood and kindling and light.  Cover the pit using the tin as a cover with at least one hole to allow air into the fire.  Let it burn down.  It will take most of a day.  This will harden the walls of the pit and allow for more even heat flow when you first add the pottery.

  • I use clay that I dig out of the ground and process, but it can be commercial clay.  Keep your pieces heavy and your clay should have some grog to it.  This is not a process for fine clays like porcelain, at least not the way I do it.

  • Line your pottery onto the shelves, filling the kiln with the kindling and wood as you go.  Each pot should be filled with wood shavings or dung and should be surrounded with the same.  Large pieces should go into the center.  You can stack pieces of pottery onto of each other, but keep things packed in so that they won't fall and break as the fuel burns.  All pots should be completely covered with fuel.

  • Keep a small amount of hardwood chips and branches to add to the fire as the day progresses.

  • In many cultures before the pottery was fired a prayer or blessing was said.  Often pots will be lost, and you won't know exactly why.  I have had pits filled with 20 or more pots and not lost one.    Once you light the fire your work is left to fate, but you learn with each firing.  Trial and error will be your teacher.

  • Light the fire when the pit is filled.  Have a pair of oven mitts, or fire retardant gloves on hand, you will need them in about an hour.

  • Let the fire roar, to make sure that it is burning all the way to the bottom.  Add more fuel as coals start to form, and then cover with the tin, allowing for at least one air hole.    The tin will buckle a bit, and that is fine. 

  • Continue to feed a bit into the fire through the air hole and shift the sheet a bit once in a while, moving the air hole on the edge, gradually.  Don't take it off or the shock of the cold air will crack your pots. 

  • Allow for a full day, at least eight hours, as the fuel burns away slowly, and add fuel as much as possible during this time.  Allow another eight hours to cool down as the coals burn away completely.   This process has to be monitored so that you don't set the woods/pasture/neighborhood on fire.  Have some water near by or something to put out any run away spark.

  • The next day, when the coals have burnt away and there is nothing but ash, take the tin completely off the pit.  Your pottery might still be hot, and the their might still be hot coals, so allow for a bit of time, a couple of hours, for cooling. 

  • Take the pottery out of the ashes.  They will be smokey, and have changes in the color on the surface, but they should be fired.  You won't get stone ware out of this process, but it should be hard and hold water.  If you have some silica sand in the clay sometimes you can see some lovely sparkles on the surface. 

Pit firing clay can be a rewarding, spiritual experience, but it takes time and commitment.  Enjoy it, but go into it with the idea that life is a learning experience and the things that fail are sometimes the things that teach us the most.

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Annie Hintsala
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thestickman
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Annie Hintsala
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thestickman
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Judith Barton
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Posted on Apr 22, 2012