Roger Gallardo on thu 30 jan 97
>Is there a "gum" material that can be applied over a glazed surface
>that allows a subsequent application of stain or glaze to flow more
>freely?
The "gum" that is being referred to is most likely CMC (abbrev. of
carboxymethylcellulose), an organic gum used as a glaze thickener,
suspension agent, and brushing medium. One method to use the gum is
to dissolve approximately 22 grams of CMC in about 32 ounces of water
and allow to sit for about 1-2 days. You now have a solution that can
be added in small amounts as a medium for brushing (about 2
tablespoons per pint) or used alone as the medium for brushing stains
or other glazes over another glaze. This is a frequent technique used
by people doing majolica. You can also add the dry CMC to a batch of
glaze at approximately 1/2 to 1 1/2 %. As with the solution, allow
the glaze to sit at least a day or two for the CMC to thoroughly
dissolve.
Laguna Clay Co. and most ceramic suppliers carry CMC and can be
purchased for about half the cost of arabic and one fifth the cost of
tragacanth (2 other gums). Although not as good,CMC seems to work
well and is more readily available than the other two.
Roger Gallardo
Technical Advisor
Laguna Clay Co. CA
Jim Horvitz on fri 31 jan 97
Roger I have used CMC in the past and found that the viscosity of the
material was critical. A formula could change depending on the CMC grade.
What viscosity is the material you are selling ? Do you sell other
hydrophylic cellulose materials. Jim Horvitz
Robert Kittel on sat 1 feb 97
At 11:48 AM 1/30/97 +0000, you wrote:
>----------------------------Original message----------------------------
>>Is there a "gum" material that can be applied over a glazed surface
>>that allows a subsequent application of stain or glaze to flow more
>>freely?
>
>The "gum" that is being referred to is most likely CMC (abbrev. of
>carboxymethylcellulose), an organic gum used as a glaze thickener,
>suspension agent, and brushing medium. One method to use the gum is
>to dissolve approximately 22 grams of CMC in about 32 ounces of water
>and allow to sit for about 1-2 days. You now have a solution that can
>be added in small amounts as a medium for brushing (about 2
>tablespoons per pint) or used alone as the medium for brushing stains
>or other glazes over another glaze. This is a frequent technique used
>by people doing majolica. You can also add the dry CMC to a batch of
>glaze at approximately 1/2 to 1 1/2 %. As with the solution, allow
>the glaze to sit at least a day or two for the CMC to thoroughly
>dissolve.
>
>Laguna Clay Co. and most ceramic suppliers carry CMC and can be
>purchased for about half the cost of arabic and one fifth the cost of
>tragacanth (2 other gums). Although not as good,CMC seems to work
>well and is more readily available than the other two.
>
>
>Roger Gallardo
>Technical Advisor
>Laguna Clay Co. CA
I have found that in using CMC, an addition of as little as 1/4 of 1% to the
mixed glaze is sufficeint. Also, if you do not wish to wait for two days to
use your glaze, disolve the CMC in a blender with hot tap water and add it
to your glaze slowly as it is being mixed.
R Kittel
Clay Design Inc.
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