Carty Ellis on wed 7 sep 05
I have recently tried The Glossy Liner Glaze mentioned in Mastering Cone 6
Glazes. I love it - nice feel as well as great look. It doesn't feel like
glass like some clear glazes do - nice soft skin better describes it.
Here is the "But . . . " When I fire to Cone 6 with a soak, it performs
excellent. However, when I fire to Cone 6 with an "all off" drop, it
developes some crazing after a day or so. It has same look and feel - just
crazes some - and it appears the craze is actually on the clay side of the
glaze - not coming through all the way to the surface (at least not yet - I
had this happen last Friday.) The firing was a total of about 12 hours
before the sitter shut it off.
I am using Standard 182 clay body, bisqued to Cone 04. Is reformulation the
answer? I like my Floating Blue, so I need the glaze to handle the faster
cool as well as the soaking cool for the other glazes I use.
Carol Ryan-Aube on wed 7 sep 05
Carty - I have a terrible problem with it crazing too. Nice and clear but
crazing. It is from the clay side too as you mentioned. I love so many of
the glazes in Ron and John's book - Varigated Slate Blue, Bone, Bright Sky
Blue, and otheres BUT the Glossy Liner does have problems everytime I use
it. I have a cone sitter without any temp gage but I try to cool it as slow
as possible after it shuts off.
Carol Ryan-Aube
Blue Moose Pottery
Ron Roy on thu 8 sep 05
Hi Carty,
You may find that a short soak at the end of your firing will "attach" the
glaze better - and you can still fast cool.
You may also find that the glaze may delay craze on that clay - there is a
way to test for that in our book - page 44 - 45.
I can also reformulate the glaze with a lower expansion - and you can
probaly use it in the slow cooling as well.
Glossy base 1 & 2 both have a lower expansion by the way - you may wish to
try them and see if there is still the problem - it would help me know just
how much to lower the expansion of the glossy liner.
Just let me know if you want me to do it.
RR
>I have recently tried The Glossy Liner Glaze mentioned in Mastering Cone 6
>Glazes. I love it - nice feel as well as great look. It doesn't feel like
>glass like some clear glazes do - nice soft skin better describes it.
>
>Here is the "But . . . " When I fire to Cone 6 with a soak, it performs
>excellent. However, when I fire to Cone 6 with an "all off" drop, it
>developes some crazing after a day or so. It has same look and feel - just
>crazes some - and it appears the craze is actually on the clay side of the
>glaze - not coming through all the way to the surface (at least not yet - I
>had this happen last Friday.) The firing was a total of about 12 hours
>before the sitter shut it off.
>
>I am using Standard 182 clay body, bisqued to Cone 04. Is reformulation the
>answer? I like my Floating Blue, so I need the glaze to handle the faster
>cool as well as the soaking cool for the other glazes I use.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ron Roy on thu 8 sep 05
Hi Carol.
I'm including the post I sent about this to Carty - I'll do the same for
you if you want - but try the glossy base one and two first - so I know how
much I have to change it - every clay is different so sometimes we have to
make the glazes fit.
I do hope you are using large witness cones - if you don't know what
temperature you are firing to all the help in the world is not going to
make your firings predictable.
RR
Hi Carty,
You may find that a short soak at the end of your firing will "attach" the
glaze better - and you can still fast cool.
You may also find that the glaze may delay craze on that clay - there is a
way to test for that in our book - page 44 - 45.
I can also reformulate the glaze with a lower expansion - and you can
probaly use it in the slow cooling as well.
Glossy base 1 & 2 both have a lower expansion by the way - you may wish to
try them and see if there is still the problem - it would help me know just
how much to lower the expansion of the glossy liner.
Just let me know if you want me to do it.
RR
>Carty - I have a terrible problem with it crazing too. Nice and clear but
>crazing. It is from the clay side too as you mentioned. I love so many of
>the glazes in Ron and John's book - Varigated Slate Blue, Bone, Bright Sky
>Blue, and otheres BUT the Glossy Liner does have problems everytime I use
>it. I have a cone sitter without any temp gage but I try to cool it as slow
>as possible after it shuts off.
>Carol Ryan-Aube
>Blue Moose Pottery
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
John Hesselberth on thu 8 sep 05
On Wednesday, September 7, 2005, at 02:02 PM, Carty Ellis wrote:
> Here is the "But . . . " When I fire to Cone 6 with a soak, it performs
> excellent. However, when I fire to Cone 6 with an "all off" drop, it
> developes some crazing after a day or so. It has same look and feel -
> just
> crazes some - and it appears the craze is actually on the clay side of
> the
> glaze - not coming through all the way to the surface (at least not
> yet - I
> had this happen last Friday.)
Hi Carty, Carol,
A couple suggestions. First it could be that the glaze is not getting
bonded to the pot when you are fast cooling. Even though you are
wanting to fast cool, you could use a soak at peak temperature for 15
minutes to give that molten glaze time to bond a little better. If that
doesn't work it is pretty easy to lower the expansion coefficient on
this glaze. For a first try just reduce the wollastonite to 11 and
increase the talc to 10. That was enough to stop the crazing for
another person who asked me for help a few months ago. You are
basically increasing the magnesium ( a low COE material) and reducing
the calcium (a moderate COE material).
I would still recommend a 15-20 minute soak starting when cone 6 has
bent to about 2 o'clock. That should not hurt your fast cooling glaze.
Regards,
John
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