[Clayart] Thanks and Sumi's kiln works fine now

sumi sumi at herwheel.com
Sun Oct 2 21:36:38 EDT 2016


I'm not really worried about pots exploding and I understand the fuel 
savings of not preheating. I do it because the glazes used to come out 
pinholed or bubbled if I didn't and I'm sure that is because of the 
lumpy bumpy walls in the fiber kiln. Or something about it. Also because 
it seemed to take a long time to get a draft going - again, probably 
because the chimney was restricted by collapsing fiber. I learned to 
preheat with the door cracked to avoid the gas building up in the bottom 
of the kiln. But I'll try 1/2" first and see how long it takes to fire. 
One step at a time.

> Sumi,
> May I ask a favor?
> Will you please try firing the kiln with no preheating?
> Use the same settings you used with this last firing except just start it
> cold and go for it.
> The kiln I fired at school, turned on 1 wci to start, damper a #3 (I drew
> pencil lines every 1/4²).
> After two hours kiln was at 1000F, NEVER had ANY problems with student
> work exploding or anything else.
> Then increased gas pressure to 2 wci, at 1600F pushed in damper to #2 3/4
> mark, started reduction.
> Another hour increased gas to 2 3/4 wci at that was it.
> At 2000F, pulled damper back to #3 mark.
> Cone 6 over in 7 - 8 hours.
> Perfect copper reds, celadons and shinos.
> Did the same thing at Mel¹s, just kicked the kilns on and let them go.
> Last time I preheated a kiln was back in 1973Š.
> Bill
> Bill Schran
> www.creativecreekartisans.com
> wschran at cox.net
> On 10/1/16, 6:15 PM, "Clayart on behalf of sumi"
> <clayart-bounces at lists.clayartworld.com on behalf of sumi at herwheel.com>
> wrote:
>> Just wanted to thank everybody who responded to me and tell you that my
>> latest firing was just about right. 6.5 hours to cone 7, with an
>> overnight preheat. Temperature and reduction pretty much even
>> throughout.  Pretty much the only changes I made were I took away the
>> bag wall and moved the bottom shelf back towards the back wall. And I
>> took out the extra bricks I had put underneath the load to baffle the
>> flames. I'm sure I can tweak it a bit and make it more perfect but now I
>> know what I might want to do.
>> Bill Schran, I can't thank you enough for telling me that if you pull
>> the damper out the heat goes to the bottom. I'm so glad you caught that
>> in my first post. Now my kiln fires right side up. Turning down the gas
>> pressure or pulling out the damper both do exactly the opposite of what
>> they used to do!
>> The next step, Mel, is to try preheating with 1/2" instead of 1" of
>> pressure to save fuel and protect the bricks.
>> Sumi

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