Bob Chance on mon 23 aug 99
A question has arisen among a few local potters about the difference
between Veegum-Cer and CMC.
Does anyone know if they are the same thing? Close? Can or cannot be used
in the same manner? Its truly a wonder how much info there is in this
group if you ask the right question.
Bob Chance
Vince Pitelka on tue 24 aug 99
>A question has arisen among a few local potters about the difference
>between Veegum-Cer and CMC.
>Does anyone know if they are the same thing? Close? Can or cannot be used
>in the same manner? Its truly a wonder how much info there is in this
>group if you ask the right question.
Bob -
As I understand it, Veegum-Cer is a mixture of Veegum-T and
carboxymethylcelulose (CMC). For those who don't know, Veegum-T, like
Macaloid, is a super-refined bentonite.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Tom Buck on tue 24 aug 99
Bob C:
CMC is short for carboxy methyl cellulose (sodium salt). This is a
derivative of wood-pulping/paper making. The insoluble wood fibres are
chemically chopped apart until the starchy polymer comes down in
meolecular size and thus the behaviour is altered. CMC is soluble in
water, perhaps to 5 wt% or more in hot water. Then the solution can be
added in small amounts to a newly mixed glaze. CMC acts as a suspension
agent (keeps colloidal particles from settling out too quickly); it will
serve as a mild plasticizer in claybodies/slips; it will act as an
adhesive to cement the glaze to a pot's surface.
Veegum family are natural clays, called smectites, and the several
varities offered by RT Vanderbilt (div WR GRace Co) have somewhat
different enduses although they all serve as suspension agents and clay
plasticizers. I gather that Veegum-Cer is aimed mainly at the clay
products industries to improve workability of clay slips.
| |
|
