[Clayart] red refire [GroupMail]
ivor and olive lewis
iandol at westnet.com.au
Thu Jan 2 00:25:47 EST 2014
In the chemical lab of the Steel Company where I worked they had to check
every ingot for its Hydrogen content, and to devise ways of eliminating
hydrogen from inter atomic lattice space. If this was not done the steel
would fracture due Hydrogen Embrittlement while it was being processed or
under service stress; Forged, rolled, even welded. Free individual Hydrogen
molecules have high velocity . Heat treatment was the answer. To ensure
there was no hydrogen in fabricated components, like helicopter rotor hubs,
The welding rods we made for custom designed alloys were baked to remove
water and hence, eliminate occluded Hydrogen.
To my mind, the method you employ not only supplies Carbon via Carbon
Monoxide, but more importantly molecular Hydrogen from wood chips which can
rapidly diffuse into and through the disordered and disrupted glaze silicate
lattice and freely react with Copper Oxide molecules.
A Happy New Year to You
--- Original Message -----
From: "mel jacobson" <melpots2 at visi.com>
To: <Clayart at lists.clayartworld.com>
Sent: Thursday, January 02, 2014 12:42 AM
Subject: [Clayart] red refire [GroupMail]
>i had a fun time with bob anderson after his new years
> firing of pots...he got bright green and white red pots.
> he called and said...`what did i do wrong?`
> we laughed together.
> i told him to `take out the good pots, (some temmoku and white.) and just
> re fire
> the red. i have a plan.`
> i have had three really great red firings this past two months.
> all racers.
> he re stacked the kiln, and fired to cone 10.
> light reduction the entire way. sort of a speed firing
> past 500F.
> i told him to close down the kiln and load in wood sticks.
> tight kiln.
> do that four times as it cools. bob has an outdoor kiln. smoke not
> an issue.) i have vent fans and never stay in the kiln room during
> when the kiln gets to 1750F turn on one burner and
> bring the temp back to about 2000F. it goes fast, takes
> about an hour. then let it cool slowly.
> keep the kiln tight.
> he did it just that way.
> opened the next day and every pot was bright red.
> all re fired.
> this was an old nils theory about two cooling cycles, and pete
> pinnel has even suggest firing green pots over in an electric kiln.
> red needs a cooling cycle with reduction, in my opinion. and
> it needs two really well orchestrated cooling cycles past 1700F.
> i am convinced that reduction during cooling works.
> many scoff. they talk about the pots sealing etc.
> i don't believe that for a second. pots are liquid until
> late in the cooling cycle. how can they seal at 2000F.?
> clay body may not change much, but glaze is liquid. it just
> makes sense to me...and i have done it for years.
> in fact bob anderson and i have fired many kilns at the farm
> with no reduction on the way up...and did al the reducing on
> the cooling cycle. got great pots. great reduction color.
> something to chat about in the new year.
> this is a theory that needs doing, not just a theory.
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
> new book: http://www.21stcenturykilns.com
> clayart: http://www.ceramicist.org
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