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question on "mastering cone 6 glazes" spearment

updated mon 25 jun 07

 

Laura Macgregor on thu 21 jun 07


I recently mixed up the high calcium semimatte glaze (page89/91) and
coloured it with 4%copper carbonate and 6% rutile. I have a lovley leafy
green. However the glaze is very runny and has been running off my bowls
and sticking to the kiln shelves. Any sugestions on how to resolve this
problem. Should I thin the glaze more by adding water?? The glase is very
shiny and almost transulant on the rims of the bowls. It doesn't look like
the picture in the book.However I'm using plainsman gray clay and not
porcelain as in the book photo.

John and Judy Hesselberth on fri 22 jun 07


Hi Laura,

Are you very sure you are firing only to cone 6? I'm not meaning what
your kiln controller is telling you, but what large cones placed on
every shelf tell you. It sound like you are overfiring or have made a
mixing error.

Regards,

John

On Jun 21, 2007, at 2:03 PM, Laura Macgregor wrote:

> I recently mixed up the high calcium semimatte glaze (page89/91) and
> coloured it with 4%copper carbonate and 6% rutile. I have a lovley
> leafy
> green. However the glaze is very runny and has been running off my
> bowls
> and sticking to the kiln shelves. Any sugestions on how to resolve
> this
> problem. Should I thin the glaze more by adding water?? The glase
> is very
> shiny and almost transulant on the rims of the bowls. It doesn't
> look like
> the picture in the book.However I'm using plainsman gray clay and not
> porcelain as in the book photo.
>

Laura Macgregor on sat 23 jun 07


Hi John
yes I did over fire in one firing.Cone 7 had bent right down. However the
first time I used the glaze I had a true cone 6 firing.The green was the
same colour as the overfire.It was not quite as runny but still flowed a
little onto my kiln shelf. I thought I mixed it up correctly but perhaps
not.I was wondering if I could attempt to make it less runny by adding
another 5 % EPK. Thank you for your reply
Laura

Chuck Wagoner on sat 23 jun 07


Did you use CSM base 1 or 2? 1 is stiffer, I use it for the Raw Sienna,
Spearmint and Bone color combinations, although the book shows them in 2.
They are just a little more mat. Don't be afraid to put the CSM glazes on
thin. Experiment with how thin you can put them on. Slow cooling is a must
as you probably already know.

Chuck
...big fan of Ver. Slate Blue

>>same colour as the overfire.It was not quite as runny but still flowed a
>>little onto my kiln shelf. I thought I mixed it up correctly but perhaps
>>not.

Laura Macgregor on sat 23 jun 07


I used csm base 2.I see base 1 has a little more EPK. I did have the glaze
quite thick . I'll try a thiner coat and I'm still considering to add 5%
more EPK. .Is your spearment a light green or more leafy looking? (Yes I
do a slow cooling)
Thanks for your reply

Fred on sun 24 jun 07


cutting back a bit on the rutile might work OR it needs alumina (more clay)
---- Laura Macgregor wrote:
>I recently mixed up the high calcium semimatte glaze (page89/91) and
>coloured it with 4%copper carbonate and 6% rutile. I have a lovley leafy
>green. However the glaze is very runny and has been running off my bowls
>and sticking to the kiln shelves. Any sugestions on how to resolve this
>problem. Should I thin the glaze more by adding water?? The glase is very
>shiny and almost transulant on the rims of the bowls. It doesn't look like
>the picture in the book.However I'm using plainsman gray clay and not
>porcelain as in the book photo.
>
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