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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.

Regards,

Bonnie Staffel
http://webpages.charter.net/bstaffel
http://www.vasefinder.com/
Potters Council member