TAPPI T 648 om-09

This method describes a procedure for the determination of the low- and high shear viscosity ofcoating clays. This is accomplished by the preparation of a completely dispersed 70% solids aqueous claysuspension with incremental introduction of dispersant to obtain the optimum dosage (minimum viscosity) for thelow and high shearing rates.

At 70% solids content, not all clay slurries are sufficiently fluid to permit viscosity determinationswith the usual instruments. The test as written is thus substantially limited in its applicability to the type of coatingclays suitable for high solids coating. A similar test procedure using lower solids content is informative in the caseof clays such as calcined and delaminated coating clay that are not suited to testing at 70% solids. In each case thesolids content should be maintained at as high a level as possible to accentuate differences between the clays inquestion.

Coating clays are available in predispersed slurry form, generally at 69.5-70.5% solids. Theprocedure for determining the viscosity characteristics of these clay slurry shipments is also incorporated in thismethod.

Product Details

Published:

10/01/2009

Number of Pages:

9