[Clayart] discussion topics

ronroy at ca.inter.net ronroy at ca.inter.net
Sat Jan 11 17:09:09 EST 2020

I should add - we recommend a hold be started when the cone you are  
firing to just starts to bend. The cone will continue to fall and the  
cooling can start when you shut off at the cone bend you want.  
Watching your cones bend to desired fall seems to me to be the best  
situation to get your firings to come out the same.


Quoting ronroy at ca.inter.net:

> John and I recommend a 20 minute hold for cone 6 firings - I have  
> always held for 30 minutes in my over 1000 gas firings. It helps  
> eliminate pinholes, makes for a better clay/glaze bond and helps to  
> even out temperatures inside a kiln.
> I have never seen a glaze run off a pot with a short hold. We should  
> be looking elsewhere for the cause of this problem. Does she fire  
> with cones? Was it the first time she used that glaze?
> If she had the recipe I could tell for sure why the glaze would run  
> like that.
> She should call the supplier and ask their advice about this.
> My experience is very positive about slow firing and holding at the  
> end of a firing.
> RR
> Quoting mel jacobson <melpots at mail.com>:
>> 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
> Ron Roy
> ronroy at ca.inter.net
> Web page ronroy.net

Ron Roy
ronroy at ca.inter.net
Web page ronroy.net

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