Paul Haigh on tue 30 sep 08
I shouldn't have gone to bed during that last firing. I left someone in charge of the woodfiring- it was going great- and went to get a few hours of shuteye only to find out that they shot over 2000 F and had 1) not soaked it in oxidation to burn out carbon etc (single firing), 2) had not put it into good reduction when I wanted (cone 010), and 3) had actually sidestoked (causes reduction in my kiln) a bit during this meteoric temp rise because it seemed like fun. AARRGGHH!
Well, the firing results were quite good, but I did have some pieces with small bloats. I attribute these to missing the burn-out before vitrification. However- I noticed a few small pieces of some organic matter in my clay whilst throwing last night- pieces of straw or slivers of wood. Less than half inch long, pretty thin- from commercial clay, the same batch as in the last firing- but I think I used the same clay in the firing before that without bloating... hard to track right now.
In general- if I take it easy on that part of the firing in oxidation- should the pieces be able to tolerate some small inclusions such as I described without bloating? I would assume so considering some of the brick making techniques that I've seen.
Paul Haigh
Londonderry, NH
Ron Roy on thu 2 oct 08
Hi Paul,
I am sure you can get it burned out - just slow down from 700C till 900C
and make sure there is plenty of oxygen around to complete the burn. It's
the reduced iron that will over flux the clay later on.
RR
>I shouldn't have gone to bed during that last firing. I left someone in
>charge of the woodfiring- it was going great- and went to get a few hours
>of shuteye only to find out that they shot over 2000 F and had 1) not
>soaked it in oxidation to burn out carbon etc (single firing), 2) had not
>put it into good reduction when I wanted (cone 010), and 3) had actually
>sidestoked (causes reduction in my kiln) a bit during this meteoric temp
>rise because it seemed like fun. AARRGGHH!
>
>Well, the firing results were quite good, but I did have some pieces with
>small bloats. I attribute these to missing the burn-out before
>vitrification. However- I noticed a few small pieces of some organic
>matter in my clay whilst throwing last night- pieces of straw or slivers
>of wood. Less than half inch long, pretty thin- from commercial clay, the
>same batch as in the last firing- but I think I used the same clay in the
>firing before that without bloating... hard to track right now.
>
>In general- if I take it easy on that part of the firing in oxidation-
>should the pieces be able to tolerate some small inclusions such as I
>described without bloating? I would assume so considering some of the
>brick making techniques that I've seen.
>
>Paul Haigh
>Londonderry, NH
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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