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 dispersant 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 such as calcined and delaminated coating clay that are not suited to testing at 70% solids. 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 predispersed slurry form, generally at 69.5-70.5% solids. The
procedure for determining the viscosity characteristics of these clay slurry shipments is also incorporated in this
method.
| Number of Pages : | 9 |
| Published : | 10/01/2009 |
