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carbon marks in pit-firing

updated thu 11 nov 04


Heather Morris on tue 9 nov 04

During a recent pit-firing I found that the results were heavily marked =
in some places by black, shiny carbon deposits. (I think it was because =
there was paper on the surface of the pot at that place, or the bonfire =
did not get hot enough - any ideas?) I'm planning to refire them in the =
electric kiln to clean up the surface. Previously I've taken them up to =
950 degrees which has burnt off everything except really deep copper =
marks, leaving the pot virtually white again. Does anyone one know the =
minimum temperature I could use to burn away excessive carbon on the =
surface? Could I get away with much less than 950? Ideally, I'd like to =
get rid of the carbon blackening but keep some of the coloured markings =
left by the pitfire.=20

Thanks, Heather.

Bonnie Staffel on wed 10 nov 04

In my experience, the "carbon markings" are usually creosote caused from the
wood you are burning. I wash my pit fired pots in very hot water to which I
add ammonia and dishwashing soap. With a soft scrub brush, you can work on
these areas to get rid of a lot of the "tar." I would think that pine wood
would create more creosote. Use a good hardwood instead. I do not get this
lately as I have changed my wood source. Creosote also gathers on a metal
lid if you use one and when it gets hot, will drip on your pots. If you use
any sawdust, cedar pet litter is useful.


Bonnie Staffel
Potters Council member