Friday, January 27, 2012

Pit Fire Results

At first glance I thought all the test pieces we fired in the pit fire were black, just black. But look at this pinch bowl, after washing there is some gold and blue. This bowl is red stoneware with Florida clay slip applied around the perimeter and bisque fired beforehand. We used citrus fertilizer, miracle grow, and salt sprinkled liberally over the wares before firing, nothing else.

Keep in mind the pieces we fired are test pieces. This one is what I call a brush holder, open at the top and bottom. This was fired green, no bisque. Amazingly it did not crack or break. Food for thought.

This pinch vase was bisque fired beforehand and got smokey color and one tiny spot of copper color. Why? I have no idea. We placed pieces of copper inside the pieces, but  I think the copper was too thick to melt and produce the color we were looking for.

This flower form was bisque fired beforehand and only has carbon colors showing.

These are the two pieces Fran included in the pit firing. Notice the piece on the left has a leaf pattern which is visible. Fran embedded the leaf in the clay during construction, using a delicate cypress leaf and firing it green. The oblong leaf was also fired green. Although we didn't get the colors we hoped for, we now know we can fire green and get the same results. However small it may be, this is progress. Thanks for reading and for all your comments.


  1. Hi Linda, what fun you are having with your pit firing. Impressive to have done a few unbisqued and have them survive. I have found more colour when coating with terrasigalta and burnishing the pieces then bisque at 900 deg C before firing. A light sprinkle of copper oxide can then produce reds. Good luck with your experiments.

  2. Did you put terra sig on the pieces before bisque? You can get great color that way. Also wrapping them up in aluminum foil with moss, copper carb, etc. will give you some reduction colors. I have a recipe called swamp juice somewhere, but if you google Edge Barnes and swamp juice I think it's on a Ceramics Daily site.... he gets really nice results with it. I used it last time I did a pit fire and got some crazy reds.
    I personally like the black with the smokey effects though. Looks good!

  3. haha, I think Anna was posting at the same time, I didn't see her comment until after I posted mine, sorry for the repetition :)

  4. Hi Anna, thanks, yes I was surprised that they didn't crack, with clay it's never hurts to experiment. Why does the terra sig produce better colors? I have used copper carbonate, will that work or do I need to use copper oxide?

    Hi Tracey, thanks, when I did my barrel firings I used burlap soaked in salt and dried and then wrapped the pots in that along with RIO and copper carb and salt and got some good results, next time I'll do the same but I'll use a clay slurry coating over the burlap (saggar) and see what happens. I saw that swamp juice article some time ago, but forgot about it. I'll try some next time. I would love to get those reds.

  5. I might need to hear it twice for it to sink in, Ha.

  6. wrapping thin copper wire and copper brillo pads...

    our friend burnishes and it is beautiful..

    love following your clay adventures, Joan

  7. wow... catching up on blog reading. love hearing about your pit firing. banana peels- they can work well. Becky Story knows more about all this than me. I echo all the materials mentioned in the other comments... seaweed (wet) is good, i've found. Yes, copper wire! I also like to wash the pieces in murphy's oil soap afterwards--- brings out some additional color too. gosh, I miss pit firings! have used burlap cord too... or twine too. good luck!

  8. Hi Joan, thanks, I used those in my barrel firings, but didn't get organized enough for this one. I'll have to try that burnishing one of these days. I still read your blog too, one of these days I hope to get up there to visit.

    Hi Amy, thanks, perhaps we can all meet one of these days and have a group firing, wouldn't that be fun? so much I want to do and so little time to do it. wouldn't the wet seaweed make the pots explode by putting moisture on them? I've used dried seaweed before.


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