[Clayart] discussion topics

Paul Gerhold gerholdclay at gmail.com
Thu Jan 9 04:53:39 EST 2020


Holding a firing at max temp is effectively just firing at a higher cone. Nothing wrong with doing it.  Any time you are working on developing a new glaze you should fire at different cones and with or without holds or down firing till you find out what suits your aesthetic. 

Just did a test where the piece was elevated on a clay disc and deliberately fired to run the glazes.  End result a vase that is sitting on glaze feet about a half inch above the table.  Just wonderful. Going to fire a kiln load to see if this can have a reasonable success rate.  

Paul

> On Jan 8, 2020, at 5:35 PM, mel jacobson <melpots at mail.com> wrote:
> 
> my new adult student has been working on cone 6, mel6 and our glazes.
> she had a firing and a commercial rutile blue glaze ran right off
> the pot onto her kiln shelf.  obviously she was puzzled, she also
> has some crazy pin holing in that glaze.
> 
> in discussing the problem she mentioned to me that she has
> programmed a hold at cone 6 for something over 30 minutes.
> i told her not to hold at temp.  no need.  that is old wives tales
> and in a program kiln who knows if the temp does not rise during the hold.
> hit the mark, turn off the kiln.  down fire should be at 1900F.  and, who
> knows if you need down firing?  (we all know what carol is doing with
> high iron glazes...and most of you know that i fired hare's fur at cone 12
> with a down fire. in many cases i turned pots into bright metallic gold.)
> but, i was firing all my hare's fur, partridge feather and oil spot glazes
> in oxy atmosphere, or only slightly neutral. no reduction.  high iron clay, and
> high iron glazes. they look like they come from a fuel, reduction kiln...as in
> look like..but not.  that is the key to hare's fur. fired in saggers in a wood
> fired, very hot kiln.  no kiln shelves at all.  400 pots fired in a chamber.
> the pots were snug in a neutral atmosphere, in a really wild wood fired reduction
> kiln.  i have never seen puke green in my firings. clean atmosphere in the kiln.
> (many of us saw puke green in that old temmoku recipe of the late 60's. and remember
> folks turned the world full of smoke from over reduction..we all did it. not now.
> over reduction is a scourge.)
> 
> i am convinced that there is a reaction with that high rutile content
> glaze sort of boiling at the clay surface.  high iron clay, high iron
> glaze. (and i think some titanium) they may not be compatible, or make the bubbles and pin holes part
> of the aesthetic. make the so called flaw a new signature glaze.
> we did that with colleen and the boiling shino.  now we do not get the
> boil...it is back to lovely orange and black basic shino.   it may be as
> simple as a dead mouse rotten in the shino.  who knew?  i think it was too
> much table salt.
> 
> i would love to have others join in on this topic...especially about holding
> at temp...i would like to ban it.  only bad things happen.
> that is one reason i always fire a new glaze to one cone hotter.  i want to see
> what happens.
> 
> i fired two bowls with mel6 and our five equal amounts of glaze materials to cone
> 12 last month.  they looked great...they still had a ring...but, man, that is pushin
> to the limit.  how does one know, unless you try to test to limit?
> 
> (thanks paul, you know how to push limits too...and we appreciate it. and,  if we
> can make our dear woofey jump...that is fun. by the way folks, i have known david
> woof since he was a baby wolf. you cannot find a kinder better person to sit and have
> a beer with. like paul, he loves controversy like air itself. they make clayart rich.)
> 
> website: www.melpots.com
> 


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