[Clayart] pin holes

Daphne Vega dvega at meca.edu
Tue Jul 23 13:04:55 EDT 2019


Thank you Snail and Ron- and it was great seeing you both at NCECA! I've
know about escaping gasses and I think that is in line with what Snail is
saying, that these solids do not get a chance to become gas in the bisque
if it is not a properly oxidized environment, getting released in the final
firing causing glaze problems (which are really clay body problems)
Ron- you are saying that the unintended reduction actually causes uneven
maturity all over the piece (around the iron) and I get how that makes
pinholes and bloating- so why would it matter if you could reoxidize, isn't
the damage already done?
My thinking has been that I bisque to a lower temp than when I body reduce
so I'm in a safe zone (because i'm not reaching the temp needed for
reduction)- can the Fe2O3 give up its O2 at any temp? (Am I overthinking
this?)

Thanks-
Daphne


On Mon, Jul 22, 2019 at 9:55 AM Snail Scott <claywork at flying-snail.com>
wrote:

>
> > On Jul 21, 2019, at 12:54 PM, Daphne Vega <dvega at meca.edu> wrote:
> > ...reducing or oxidizing in a bisque kiln- I am
> > curious why it would make a difference?
>
> One important difference is that impurities like carbon need sufficient
> oxygen to combine with them, in order to ‘burn away’ in the bisque process.
> When this happens the carbon becomes carbon monoxide and carbon dioxide,
> a.k.a. gases, not solids, so that it can leave the clay. A kiln atmosphere
> starved of oxygen (reducing) will not have sufficient free oxygen to permit
> this to happen, and carbon will remain trapped within the clay as it
> matures.
>
>          -Snail



-- 
www.dvegadesigns.com
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