Carol Baker on thu 5 apr 01
Hi Clayarters -
I am using a translucent cone 6ox glaze on B-mix. I love it because of its
soft glow and because my underglaze work on bisque is stable with it. Also,
it does not craze thanks to a Clayarter who fixed it for me. However --- it
is labor intensive because it shows every drip or run. I have to shave or
rub down every mark. Sometimes on the back of a plate it will also form an
alligator-like skin. I have added bentonite, but I am not sure what else to
add. I've done my homework, and I think I need a binder. I have tested with
epsom salts and it was better, but still does not smooth out as much as I
would like. Would CMC or another gum be what I need or just more epsom
salts? Is there some change to the glaze recipe that might improve it?
Since this glaze has solved the crazing problem on B-mix I'm afraid to
change it.
Woods 6ox clear:
G200 feldspar 30
Dolomite 7
Whiting 16
EPK 17
Silica 30
As always, thanks for your help. I've learned so much from all of you.
Carol Baker, Scottsdale, Arizona
Maid O'Mud Pottery on thu 5 apr 01
I haven't tried this particular recipe; but I use 1/4 to 1/2% macaloid with my
satin clear and it doesn't show any drip marks.
HTH
Carol Baker wrote:
> Hi Clayarters -
> I am using a translucent cone 6ox glaze on B-mix. I love it because of its
> soft glow and because my underglaze work on bisque is stable with it. Also,
> it does not craze thanks to a Clayarter who fixed it for me. However --- it
> is labor intensive because it shows every drip or run. I have to shave or
> rub down every mark. Sometimes on the back of a plate it will also form an
> alligator-like skin. I have added bentonite, but I am not sure what else to
> add. I've done my homework, and I think I need a binder. I have tested with
> epsom salts and it was better, but still does not smooth out as much as I
> would like. Would CMC or another gum be what I need or just more epsom
> salts? Is there some change to the glaze recipe that might improve it?
> Since this glaze has solved the crazing problem on B-mix I'm afraid to
> change it.
>
> Woods 6ox clear:
> G200 feldspar 30
> Dolomite 7
> Whiting 16
> EPK 17
> Silica 30
>
> As always, thanks for your help. I've learned so much from all of you.
> Carol Baker, Scottsdale, Arizona
>
--
Sam, Maid O'Mud Pottery
SW Ontario CANADA
http://www.geocities.com/paris/3110
scuttell@odyssey.on.ca
"First, the clay told me what to do
Then, I told the clay what to do
Now; we co-operate"
sam, 1994
"Effort does not always equal output"
sam, 1999
Ruth Ballou on fri 6 apr 01
Hi Carol,
This glaze is more appropriate for ^10. To get rid of the drips you need to
change the viscosity of the glaze at ^6. That means lowering the melting
temperature. Magnesium gives a nice buttery surface to glazes, but it is
also has the highest surface tension of all the oxides and in high
quantities is used to make alligator glazes ( does this sound like the back
of your plate?). It can be used in ^6 glazes if there are a variety of
fluxes to help smooth out the surface. There are three factors to consider
when choosing fluxes for a glazes: the attributes each particular flux
used, the quantity of each flux, and the number of fluxes. The addition of
another flux usually lowers the melting temperature of a glaze even if the
percentage of fluxes in the glaze is adjusted and held constant. In
addtion, at ^6 boron is frequently used for its strong fluxing properties
as well as its anti craze action. This glaze has only calcium and magnesium
as fluxes ( in addition to the KNaO from the spar). The calcium is high for
a ^6 glaze and is more likely creating an underfired matt. Finally, the
expansion for this glaze is high, even with the magnesium (which is another
oxide useful against crazing). In short, I'm sorry to say, there is so much
wrong with this glaze at ^6 that it is probably better to start over with
another glaze, because by the time it's fixed it won't be the same glaze
anyway. Try searching the archives for ^6 majolica glazes, as extensive
work has been done by Ron Roy and other clayarters on these glazes. This
type of glaze will be stable and show brushwork. If you find one that you
like, but is too opaque for your needs, you can try reducing the opacifier
(tin or zircopax).
Good searching and good luck!
Ruth Ballou
>
>Woods 6ox clear:
>G200 feldspar 30
>Dolomite 7
>Whiting 16
>EPK 17
>Silica 30
>
>As always, thanks for your help. I've learned so much from all of you.
>Carol Baker, Scottsdale, Arizona
>
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