Xantham Gum

Notes

Xantham Gum is a versatile polysaccharide thickener and suspension agent produced by the fermentation and extraction of the naturally occurring plant-bacteria Xanthomonas campestris.

Used as a hardener in glaze slurries. It is biosynthesized from a bacteria (after which it is named).
This is a widely used product, other grades are available for pharmaceutical and personal care products, for example.
Since this is organic, a preservative or biocide addition is often needed if the product will be stored for some time.

Related Information

Xantham gum seals clay against water slaking

These two 4mm thick pieces of clay have had 1% of an Xantham gum added. The gum was just shaken together with the powder and then 21% water was added and it was stirred in a cup and then wedged to plastic working consistency. The piece on the left was underwater for 1 hour! Without the gum it would have slaked within a couple of minutes. Of course, there is an issue, the gum destroys the plasticity of the clay!

Mold growing in a clay having added xantham gum

This slug is about 6 months old. It contains 0.75% gum. The gum destroys the workability of the clay so it is not useful in this application anyway.

Links

Oxide	Analysis	Formula

URLs	http://en.wikipedia.org/wiki/Xanthan_gum Xantham Gum on Wikipedia
Materials	Vanzan
Materials	Rhodopol
Typecodes	Additives for Ceramic Glazes Materials that are added to glazes to impart physical working properties and usually burn away during firing. In industry all glazes, inks and engobes have additives, they are considered essential to control of cohesion, adhesion, suspension, dry hardness, surface leveling, rheology, speed-of-drying, etc. Among potters, it is common for glazes to have zero additives.

By Tony Hansen
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