This method describes a procedure for the determination of the low- and high-shear viscosity of coating clays. This is accomplished by the preparation of a completely dispersed 70% solids aqueous clay suspension with incremental introduction of a dispersing chemical to obtain the optimum dosage (minimum viscosity) for the low and high shearing rates.
At 70% solids content, not all clay slurries are sufficiently fluid to permit viscosity determinations with the usual instruments. The test as written is thus substantially limited in its applicability to the type of coating clays suitable for high solids coating. A similar test procedure using lower solids content is informative in the case of clays not suited to testing at 70% solids, but in each case the solids content should be maintained at as high a level as possible to accentuate differences between the clays in question.
Coating clays are available in predis-persed slurry form, generally at 69.5 – 70.5% solids. The procedure for determining the viscosity character-istics of these clay slurry shipments is also incorporated in this method.
| Number of Pages : | 8 |
| Published : | 06/01/2003 |
