[Clayart] Too much Neph Syenite in a Cone 10 slip glaze for soda firing

[Hank Murrow]

Hey Helen;

When I entered the pottery the next morning(by the back way through the kiln room!) someone said, "Bob is looking for you”. Bob James was the teacher, so I was worried. I found him in his office and he said, “It got a little hot in your kiln”. He looked at his pocketwatch and asked, “Do you have any afternoon classes?” I said no(lying) and he said, “There are new shelves and posts in the attic, so if you work this afternoon, you could have the kiln firing again by dinnertime”. Whew! I said to myself, and sure enough I did fire it again the same day, and into the next. Came out perfect. There were Voulkos pots in that first firing, and because they were made from fireclay and sand, they had held the broken kiln shelves off of the melted studio pots that littered the broken sheves. We sent those pots with which Pete had demonstrated to him; and he said they were the best he had gotten from any of his workshops(back in the late fifties anyway)! As another teacher in the art dept. was famous for saying, “Who knows what is good luck or bad luck!”

Cheers, From Eugene(yeah, I am still here near my alma mater, though my teacher Bob James died this fall @ 89). Meanwhile, I have been building & firing kilns for 60 years(so far)!

> On May 4, 2018, at 9:32 AM, JOAN <jomacx at msn.com> wrote:
> 
> Hank:
> 
> It is nice to know that my first firing disaster in January was similar to yours sixty years ago.  I also over-fired because I couldn't see the cones.  They had already melted and melted the cones into their holders and the holders to the 3 kiln shelves and the kiln sitter cone fused the parts together.  Fortunately, it was just a test and no pots were in the kiln.  I hope to follow in your footsteps and NEVER do this again!
> 
> Joan
> Joan MacDonald
> 303-816-9035
> 877-554-1121fax
> website: http://joanmacdonald.bravehost.com
> Pine Grove, Colorado
> 
> 
> ________________________________
> From: Clayart <clayart-bounces at lists.clayartworld.com> on behalf of Hank Murrow <hmurrow at efn.org>
> Sent: Friday, May 4, 2018 7:58 AM
> To: Clayart international pottery discussion forum
> Subject: Re: [Clayart] Too much Neph Syenite in a Cone 10 slip glaze for soda firing
> 
> Dear Helen;
> 
> Fingers and toes crossed in Eugene, OR waiting to hear of your successful first firing. IT was different for me the first time, as I fired an old Alpine for the first time and having lost the vision of the cones, it went to C18 before I turned it off! Haven’t over-fired a kiln since, in some 3000 fires over a sixty-year span, though.
> 
> Good Luck Helen!  Hank in Eugene
> 
>> On May 3, 2018, at 12:46 PM, Helen Stone <helenestonepeony at gmail.com> wrote:
>> 
>> I did my first cone 10 soda firing this week in my new soda kiln, with over
>> 150 samples inside, including various mixes of native clays and native
>> kaolins.  For the samples, I used a slip recipe from Gail Nichols soda
>> firing book, but altered it.  This is because, for my lowest kaolin content
>> sample clay bodies, I did not think that they could last up to cone 10, I
>> thought that for they maybe would make cone 8 maturation.  These lowest
>> kaolin content samples were 20% kaolin, others were 25% and 30% kaolin with
>> corresponding lower amounts of native clays in the mix.  The reason that I
>> thought that they could only go to cone 8 is that, in and of itself ,one of
>> these native clays typically fires to cone 4 and a half, when fired by my
>> friend, the salt kiln potter.
>> 
>> So I altered Gail's slip recipe.  She called for Neph Sy 10%, Clay X 80%
>> and Silica 10%, with Bentonite additions as a basic slip for Cone 10, but
>> really her firings go to cone 11.  So I foolishly put in Neph Sy 20%,
>> leaving the other items the same %, somehow thinking that this would
>> provide for a lower melting temperature, possibly at cone 8, where was my
>> head.
>> 
>> Tomorrow I will open the kiln and see what happened.  If the slips did not
>> melt properly, I will have to change my higher Neph Sy recipe to
>> accommodate one similar to that of Gail Nichols.  Any suggestions would be
>> welcomed.   Because I have dry powdered slip mixes to the ying yang and
>> cannot waste them.   Last ditch choice for me would be to possibly weigh
>> each different dry powder slip sample and extrapolate from that, what
>> ratios  of Clay X and Silica and Bentonite I would have to add, in order to
>> bring the slip recipe up to be the same as Gail's recipe.
>> 
>> Thank you for your help.
>> 
>> Helen in Ecuador, on Rio Yambala, with happy cats
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