Dispersion of titanium dioxide in non‐aqueous media Part 4

A well appreciated difficulty in paint formulation is the scaling‐up of laboratory data, and to obtain optimum performance on a commercial scale adjustments in p.v.c. (f) and in resin solids concentration have to be made. In the laboratory the millable p.v.c. (f) of a given formulation may be above, or more usually below, the value indicated by the flowpoint data, and depends mainly on the ability of the particular milling machine to cope with the quantity and nature of the millbase. In large‐scale manufacture using high‐speed shear impellers, a somewhat higher value than the experimentally determined p.v.c. (f) can be used, but for a ballmill it will be only slightly higher than the value millable in the laboratory. The concentration of resin solids has also to be adjusted, and here it is important to ensure that it is high enough to prevent pigment reagglomeration on let‐down.