[Clayart] cone six rumors

Bonnie Staffel bstaffel at chartermi.net
Sat Nov 5 17:30:48 EDT 2016

One of my very early lessons in working in clay and the melting of glaze
ingredients, was that most they unified around Cone 10. Kilns were not
usually built to go that high in the early days of my career. I had a friend
who liked to build electric kilns and I asked him to build me one for Cone
10. Most kilns during that time would not fire that high. I purchased three
square ones, as I also felt the square shape would fit in  more pots than a
round one. So my ventures in glaze creations was at Cone 10. I worked on
these while at Cranbrook too as that was the temperature of their class
firings. When students shared their glazes, they were also Cone 10. 


Then after I was operating my own studio and selling my functional work, I
still stayed with Cone 10, but the new Cone 6 was being introduced. I tried
a couple of the new glaze recipes but they were a big disappointment to me
as to depth of color, feel, and general interaction with other elements of
the glaze ingredients. They have improved over time so I find it is
difficult to tell one from the higher fired glaze now.


I have never deviated from this Cone and mixed my clay to fit my glazes.
After I stopped mixing my own clay, I then found Cone 10 clay from
Highwater. My glazes all fit their clay as well. The trend currently seems
to lean towards cone 6 with clay and glaze offerings. 


Some time ago I purchased a beautiful mug from a well known on line gallery.
I heated my coffee in the microwave and the mug crazed horribly, spoiling
the concept. I had also given one to my granddaughter and told her to never
put it into the microwave. Seems to me that all potters should test and
attest their work to be microwave proof if it is a commonly used "mug." Even
a bowl where one might heat soup or other hot food dish in the microwave,
one would expect it to not craze. I have Cone 6 bowls made by friends that
are craze proof as I have heated liquids in those mugs and bowls for years.
They are still intact. However, I just don't basically trust that the pot is
as strong as Cone 10 Stoneware or porcelain. I have had little or no
problems with my Cone 10 mugs and bowls. 


As to Mel's comment on his last casserole, I started to throw sinks and sold
some. However, one of my friends where I had gifted one as a housewarming
present, mentioned that there was an area in the sink bowl where the glaze
had crazed. On questioning, he said that he had one of those super hot water
faucet additions that struck only that portion of the sink. I made my last
sink as I didn't want that to happen again. One really needs to stay up with
progress or how a customer uses your work. 


Next time I purchase a pot on line, I will ask the question if it is Cone 6
or if it will go into the microwave without crazing. 


Thanks for listening,







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