[Clayart] pin holes

ronroy at ca.inter.net ronroy at ca.inter.net
Sat Jul 6 14:02:59 EDT 2019

Just a word of warning - I'm not sure downfiring would re oxidize any  
iron that would have been reduced in a fast fired bisque. I wish  
someone would do some experiments to see if that is possible.

My advise for iron bearing clay would be to fire slow enough with  
enough excess oxygen present to burn off any organics present.

Keep in mind that different batches of clay in any clay body can vary  
in carbon content. The best idea is to design your bisque firings to  
make sure all carbonaceous content (usually coal) is eliminated.

Well maintained and working kiln vents and ducts are a good way to do  
this and save your lungs and elements at the same time.


Quoting mel jacobson <melpots at visi.com>:

> dead on david...pin holes almost always come from
> bad bisque firing.
> most know i fire for speed and perfect body development.
> i take everything ron says to be true.
> so...i fast fire bisque and i hold the kiln at about 1500 on the cooling
> cycle for about 30-50 minutes.
> all the junk comes out.
> ron suggested that i run experiments in down firing, or holding
> bisque firing.  it seems to work well.
> in the past i really fired slow and long for bisque.
> in some ways. i think i get the same results by down firing, or
> holding.
> others should try and report back.
> my bisque ware does not `blow'd up`.
> i fire dry pots.
> mel
> -- 
> Mel's Website:  www.melpots.com
> http://www.melpots.com/CLAYART.HTML
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Ron Roy
ronroy at ca.inter.net
Web page ronroy.net

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