Dale Cochoy on fri 28 dec 01
Ron,
Thank you so much for the reply. I am going to definitely slow down that
bisque firing even more just to be sure. I'll try to keep the kiln filled
with just this clay when I do so. I had gone to 125 or 150 at final bisque
times but I'll try at 100 max. to be sure. I'd be glad to slow it down to be
sure to save pots I've worked 2 1/2 to 4 1/2 hrs to build, and then have it
all go bad in second firing. I will also be bisque firing to cone 04 now
instead of 05 for this clay and will try to be sure I'm below cone 6 for it
( although, I was already at 5 1/2ish. )
As I said, I really like the color of this clay by it's self unglazed for
my purposes, but I have found a couple other brands that I like "Almost as
well" and, have no problems with. The bloating problem wouldn't be so bad if
it were just with slab builts, I could use other clays if in doubt, but I
get it in wheel work at it ticks me off. Yes, some are thick ( the nature of
my beast) but stacking is NEVER tight. . I was not in the practice of
leaving a spy open after about 1,100 degrees max and then closed top
completely and plugged my small vent hole in top. Perhaps I will try
leaving small vent hole open and lower spy hole open patially. I'm glad I
finally got into this after reading a couple "bloat" posts a couple weeks
ago. I'm hoping to solve lots of problems. BTW, since I'm installing a gas
kiln right now, and will be searching out good cone 8-10 clays in DARK
colors, maybe I could save myself some heartache by asking now.....Any bad
experiences there with darker clays any particular darker clays, especially
with slab work?
Regards,
Dale Cochoy, Wild Things Bonsai Studio, Hartville, Ohio USA
DaleCochoy@Prodigy.com http://www.WildThingsBonsai.com
----- Original Message -----
From: Ron Roy
To:
Sent: Thursday, December 27, 2001 11:55 PM
Subject: Re: "Bloating" revisited, FYI
> Hi Dale,
>
> I suspect that clay is on the verge of being over fired at cone 6 - I also
> agree with Standard in that I do think you are speeding up your bisque at
> the wrong time - the crucial temperature range for burning out
combustables
> (important in iron bearing clays) would be from 1300F to 1650F - I suggest
> 100F per hour and leave a spy open - even better if you are using a vent
> system attached to the kiln. If stacking is tight and/or ware is thick you
> have to be even more careful.
>
> You probably like the colour because the clay is so vitrified - still -
> standard should make some changes to that body - it sounds like a constant
> problem for them. If they need some expert help semd them to me. It's a
> simple mater of raising the maturing tepm or taking out some of the clays
> that are bringing in the contaminents.
>
> If you need more on this contact me directly.
>
> RR
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