[Clayart] crash cooling and funny story

[Robert Harris]

​Mel - While slow cooling is indeed important, the range from 2300+F (cone
10) to 2000F (which is where Anderson Ranch cooled to) is mostly completely
unimportant. The range where micro-crystals are formed is basically in the
1700-2000 range. Copper reds develop at about 1400F​. All the people that
slow cool focus in on that temperature.


On Fri, May 11, 2018 at 9:07 AM, mel jacobson <melpots at visi.com> wrote:

> kurt, nils and our group looked into crash cooling years back.
> it works to a degree, but is, in our opinion, a rather silly way to
> deal with pots.  down firing is the answer to the entire story.
> (ask me for my book if you do not have it...pdf file, free of charge)
>
> as we have talked about all winter, i am speed firing and speed
> cooling my new clay and glaze.
> but, it is natural cooling...whatever the kiln will tolerate.
> and that three hour down firing is very gentle and
> fits with the schedule.  i do not open the kiln at all
> during cooling.  watch the pyrometer go down slowly.
> but, the kiln can easily cool to 500 in about four hours.
> i do not lift the lid til it is at 150F.
> the pots have no ill effect.  they ring true, have no dunting, shivers
> or other awful problems.  there has not been a crack in the two hundred
> or more pots i have fired with my electric kiln.
>
> as happens in industry, the warm up to cone is gradual but with controlled
> speed.  the pots are in the cone area for about ten minutes or less.
> the cooling again is gradual and controlled.  no shocks, ever.
> climb to the top, and let it cool the same way.  perfect bell curve.
>
> if you open a kiln in that thousand degree range, the pots
> will be ruined.  we had a dork at the farm open our big
> stoneware kiln at 1200 and snatch his pots and went home.
> the entire kiln of pots was ruined..like 80 pieces.
> some could be saved, but most had baby cracks.
>
> if you are working for speed, you had better chart what you are doing
> and keep to a strict schedule.
>
> my study is not about rushing to get things done.
> we all can wait. never ruin pots.
> my tests are about what the clay and glaze will tolerate.
> it is about testing limits.  that has always been the study
> of mine, kurts and nils.  how far can you push, then back off.
> find the prefect system for  timing, fuel saving and  great pots
> that sing.  i have reached that point in my new firing schedule.
>
> funny story,.  i stopped at a garage sale yesterday, had a
> five dollar bill that i keep in my glove box....was looking for new
> stuffed toys for my golden...she loves new toys. 1$  each
> got 5.
> but, as i parked ,a lady with a big black bentley  car pulled next to me.
> (like 125 thousand dollar car) ?? who knows.
> i helped her out of the car, you know on a little hill and grass. she was
> like
> 70...lovely looking, great clothes.  she was old enough to appreciate a
> gentleman.
> we walked over to the tables and she was snatching a few things.
> i said to her.
> `it is really nice to be shopping at a garage sale with a lady that
> parks her bentley  and looks for bargains.` ` said the old line.
> `how do you think i can afford a bentley...?  ```  she wanted to
> buy my gold teddy bear, offered me two bucks...but, i could not
> sell saffron's gold bear,  there are limits to making money.
> mel
>
> --
> Mel's Website:  www.melpots.com
> CLAYART PAGE:
> http://www.melpots.com/CLAYART.HTML
>
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