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Rebisquing Sawdust Fired Pots

rebisquing kiln elements

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#1 firefly

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Posted 03 November 2013 - 09:52 AM

I've read that if you're dissatisfied with the results of a sawdust firing, rebisquing the pots will burn out the carbon and you can then refire them. HOWEVER, I've also read that exposure to salt will harm the elements of an electric kiln. Since I combine salt, Miracle-Gro and copper carbonate in my sawdust firings, this has me wondering:

 

1) If I rinse my sawdust fired pieces and lightly wet sand them, will that remove enough of the residual salt to prevent damaging my kiln elements?

 

2) Would combining these refires in a load with greenware negatively affect the greenware?

 

If more information helps, I use the preprogrammed slow bisque and fire to cone 010 in an electric kiln with a down draft vent system.

 

Thanks so much for any advice you can give me!



#2 bciskepottery

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Posted 03 November 2013 - 10:11 AM

What you want to avoid is a build up of salt on your elements . . . if you follow up the re-bisque with a regular bisque (no sawdust fired items) or two, you will likely burn off any salt that accumulates on your elements.  Just not a good thing to make a habit of doing.  The elements will not fail after one refiring of sawdust items; but repeated firings, you could end up with degraded elements. 



#3 firefly

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Posted 03 November 2013 - 10:23 AM

Thank you! That makes a lot of sense - sadly, I easily have a full load of refires! I'll save the greenware for a follow up load.



#4 Evelyne Schoenmann

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Posted 03 November 2013 - 11:26 AM

Hi firefly. I know you asked about re-bisquing and bciskepottery answered correctly. But: I though to myself: why not re-sawdustfire the pieces? Without any additions, only the sawdust and whatever filling material you use? Maybe one or the other smoke sign is enough to make a nice pot out of a bad pot (in terms of color). Only a thought...

 

Evelyne

 

PS: I like the pot in your avatar!


Evelyne Schoenmann
Studio: schoenmann ceramics
In love with alternative firing methods
www.schoenmann-ceramics.ch


#5 firefly

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Posted 04 November 2013 - 06:43 PM

Evelyne, thanks for your reply. One of the things I find most fascinating about smoke firings is when you can visually follow the passage of the fumes across a pot's surface. The pots I want to rebisque are those that have very heavy black carbon markings with little or no modulation. Hopefully, the carbon will burn out in the bisque firing and I can try again. Very rarely do I get a piece with what I consider not enough smoke markings - but when I do, your plan to refire it in the sawdust would be spot on.

 

As to my avatar, thanks for the compliment - I should really credit Sumi von Dassow though as that piece was fired at a pit firing workshop that she hosted last summer. 

 

Jean

 

PS: And I really like your smoke fired pieces too!



#6 Stephen

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Posted 05 November 2013 - 12:20 PM

One thing you might consider ( since your objective is to burn off carbon and thus you may not necessarily need a top notch kiln to accomplish this ) is to check craig's list for an older used one you can use just for this purpose. I check on pottery equipment daily in the Seattle area just to keep on top of what's out there and I see $50-$100 kilns come and go on probably a weekly basis.

 

One thing I have found about Craig's list is that since its free there are plenty of folks that list things at very high prices and just continually relist. Its easy to go check at any given time and conclude the going price for something is higher than it needs to be. When people really want to sell something though they usually list it at a lower price and it moves fairly quickly.

 

Cheap kilns that work usually on sit for a day or two before they get snatched up around here.



#7 Idaho Potter

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Posted 08 November 2013 - 09:54 PM

As a user of raku firings.  I'd just use my propane  raku kiln to rebisque because my pots don't get carbonized until post-firing reduction.  Maybe you could find another potter with a propane/natural gas raku kiln that would let you refire in it--no elements to harm.

 

Shirley



#8 firefly

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Posted 08 November 2013 - 10:13 PM

Stephen and Shirley,

 

Thanks for your replies. This is why I appreciate the forum - not only other's technical knowledge to draw on, but different ways of approaching a problem!

 

Jean



#9 Frederik-W

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Posted 12 November 2013 - 06:11 AM

I would not re-bisque them. It's a waste of time & money.

Just re-fire them. Old stuff will change or burn away. You will see they come out differently.

I do pit-firing and that is my experience so far.







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