# What is Cab-O-Sil and why is it in (some) powdered zinc?



## kadriver (Jul 9, 2012)

Cab-O-Sil (cabosil) is added to powdered zinc to prevent caking of the powder. If your zinc powder is free flowing with no clumps, then it may have cabosil.

Refiners of precious metals sometimes use powdered zinc to precipitate platinum group metals from solutions containing dissolved PGMs.

If the refiner uses zinc powder that has been treated with Cab-O-Sil, then the risk of contamination increases. 

Cab-O-Sil is a form of fumed silica or pyrogenic silica consisting of microscopic droplets of amorphous silica fused into particles. These particles have very low bulk density and high surface area. Cab-O-Sil has a three-dimensional structure that helps to adjust the viscosity of fluids when used as a thickener or filler.

It is also used in toothpaste (as a light abrasive), in cosmetics to diffuse light, in paints as a thickening agent, _And as an anti-caking agent in powders._

*Cab-O-Sil* is a trade name for the product and it is produced by Cabot Corporation of Boston Mass.

It is also produced by Envonik Industries in Germany under the trade name *Aerosil.*

kadriver


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