DIY Primitive Pottery Firing

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Introduction: DIY Primitive Pottery Firing

Today, ceramics are all around you. The bowls and plates that food is served on, the inside of electronics that I am typing with and you are reading on, and toilets where the contents of those bowls and plates are returned. But have you ever thought of where they came from? Most of the ceramic you own was probably made automatically by machines and fired in electric or gas kilns, but these are very recent innovations that have only been around for a couple hundred years or so. Humanity has been making pottery for tens of thousands of years by using simple wood fires, and today, I will be showing you how to do just that.

Step 1: Dig a Hole

Pretty much as simple as it sounds. You can skip this part all together and just fire your clay in a fire pit like how it was done for a very long time, but a pit kiln like this has many advantages. First of all, the temperatures are much more stable, meaning there is a lower chance of your pottery breaking during the firing process, the walls act as insulation, meaning a higher potential temperature, and you will have more control over things like wind and fuel. The shape of the hole isn't to critical, but the more spread out, the more heat you will lose to the ground. Dig it deep enough for all of the fuel to fit in, but not too deep or there won't be enough oxygen getting in to burn the fuel. My hole is about 1 foot deep (a third of a meter), but you will probably want to go deeper with larger firings. I also added a cinder block to the bottom to provide extra insulation. Ideally, this would be done on all sides with rocks, cement or clay, but you can still get sufficient temperatures without.

Step 2: Insert Greenware

Take your pieces and place them in the hole. Not much to this one, but you will need to consider logs falling as they burn, distribution of the coals, and if they break, damaging adjacent pieces. You can use most standard clay used by hobbyists (except for polymer clays). They are typically stoneware or porcelain, but I think it is more fun and rewarding to go out to a river bank and find your own clay. It will probably break a lot more than commercial clays, but the result will be unique and something you can be proud of knowing exactly where and how it got to be.

Step 3: Adding Fuel

This will basically be built like any other camp fire, the only difference is it is built in a hole, so make sure there is a path for air to get to the underside of the logs. Any kind of wood can be used really, as long as it is dry. The only thing that is really important to this process is the coals; they fall down and make direct contact with the greenware. The coals will need to cover the pottery entirely, keep adding wood until you achieve this. You might want to completely fill the space around, under and on top of the pieces with stuff like straw, dried leaves, or wood shavings. This layer will burn and deplete the oxygen, creating a reducing atmosphere, making the pottery turn a nice black color. You can even try to add chemicals to the fire like copper sulfate or even salt to add flashes of color to your pieces.

Step 4: Cooling

This part requires no labor whatsoever, the hard part is being patient; do not tamper with anything! Even without touching anything, there is a high chance of failure for wood firings. Cooling is the part where most breakage happens. As they cool, they will contract. If one part cools faster, it will of course contract faster, and cause a fracture. These fractures might be violent enough to shoot fragments off that will break other pieces. Depending on the size of the firing, cooling might take from a couple hours to well over 12 hours or longer. Don't be tempted to take the pieces out until they are almost completely cooled down.

Step 5: The Result

If you are lucky, your pieces will all turn out okay, but if there is a high percentage of breakage, it might be because of either your fire, your clay, or just bad luck. Many of my pieces had minor cracks, but were still functional. I would say this was largely successful! Try this yourself, find something that works, and experiment further. Good luck!

Want to know how I found my own clay in nature? Click here!

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    45 Comments

    If you're fortunate to live along (or near) the fall line in Georgia, you will find that the native red clay soil often has veins of white clay in it. That clay is called "kaolinite". When fired properly (heck, if even poorly fired), it makes a fantastically durable liner for high temperature ovens. You can also order it as "refractory clay" and mix it in with your native clays. (It can also be eaten; a native use here in Georgia was as an appetite supressant.)

    Digging in my yard in several places(planting trees, putting in posts,etc) have found white clay a couple of feet down. About a foot thick. Is it safe to assume this is koalinite clay? I live in the saginaw valley of michigan. I am a new to the world of clay and pottery. Would like to make my very own kiln. Any more information on this would be greatly appreciated

    Bad news - not kaolinite. There are clays heavy in calcium ("calcerous" clays) that have a white appearance, and will fire white. But they do not contain significant levels of aluminasilicate. If fired to too high of a temperature, they will basically crumble.

    I never heard of the fall line before, it sounds very interesting. Unfortunately, I live in New England, so I probably won't be coming down anytime soon. I would love to find kaolinite to make some crucibles or fire bricks, as stone ware won't work well for that. Also, I want to say kaolinite is also used to purify water too.

    It's better to pile up a mound of earth above grade and dig a hole in that (keeping the hole above grade also). By digging into the soil - once the fire is lit you can actually set root structures on fire. If you have very dry or rocky soil those roots can continue to burn long after your fire has gone out.

    I don't know much about pottery so have a question. You mentioned greenware in Step 3. What is that? Is it a certain stage of the process?

    Greenware simply refers to an item made out of clay but has not been fired yet.

    I remember hosting a class given by a Native American woman who is an artist and who pit fires all of her clay creations - pots, figures, dolls, etc. The class was fascinating! Though she did it differently. She didn't use any wood other than twigs and small pieces. It's been so long ago, I don't remember her exact technique, but I remember filling the pit with her fuel, firing, let it reduce, refill, fire again, and then a third time. After that, it seems she let it smolder for a specific time. She's on my FB friends list, so I'll have to ask her the exact procedure. I should definitely do this, since my lawn is thick, heavy red clay. Thank you for reminding me!

    Please do, and report back to us:)

    OK, folks, here you go!
    Cher Shaffer

    Local clay needs to be dried, and then screened to take out the little particles of stone. Reconstitute the clay with water. Pour water in a bucket over the dried clay, and put a lid on it, overnight. If the clay will make a nice ball, and is not too stickey to work into a shape, or crumbly and will not hols a shape, it is ready to work. Make sure finished pieces are completely dry. Check this by holding dry pieces to your cheek. If they feel cool, they still need to dry more. If they are ready to fire.

    Build the fire in a pit , burn the fire until it is embers, (my note: when we did this in class, I remember doing this three times before we put in the rack and clay items below - fill the pit, burn it off, and repeat two more times. This gets the earth good and hot) and then place a wire rack over the embers. You then place your dried pots on the rack. Cover with dried grass, hay, or leaves, that are slightly dampish. This creates the famous yellow smoke, and you want to keep the smoking going for about 2 to 3 hours. If the fire starts to flame, put more dampish materials on it, and continue to distinguish any flames this way. I usually let the fire cool overnight, and uncover the clay objects the next morning. Be careful, the clay will still be hot, and it needs time to cool, so do not get hasty in uncovering, and taking the objects out to soon. The clay objects should be a nice carbonized black color from the smoke. They are still not water tight, so do not put water, or liquid in them.

    8:49am
    Teresa McCoy

    What is the ratio of clay to sand? I remember crushing sandstone and mixing it into the clay. (My note: I remember collecting some of that bluish stone from around the creek, the kind that has little flecks in it from mica or some such mineral, though I see no reason why you couldn't use any sand, though I'd make sure it's good quality).

    Cher Shaffer

    Mix in a little sand at a times,squeezing to make sure the clay,water,sand mix will still make a ball that holds together

    Teresa McCoy

    So it's an "instinct" thing rather than actual percentages. No surprises there! I will experiment when I have some time. Thank you so much! When I'm able to give this a try, I'll send you photos so you can see how your instructions have worked.