![]() Formulators use tint strength to test the color development of the pigment being dispersed, which depends on the degree of deagglomeration and freedom from flocculation of the paste as well as the quality of the pigment itself. Tint strength (ASTM D387, ISO 787/16) is a useful test that measures the color strength of a colored paste let down into a white base by comparison with a standard. ![]() Beginners find grind gauges frustrating to use and their precision is poor, but experienced users can produce rapid, repeatable, and meaningful results. With a grind gauge, we only see the boulders, the largest particles (aggregates, agglomerates). ![]() Hegman readings of 6 and 7 correspond to particle sizes of 25 and 12.5 mm, respectively, yet the average pigment particle size will be a fraction of that, perhaps as little as 1/10th. Another reason would be to find out whether the dispersion equipment was adequate to achieve the target reading in a reasonable length of time. The main reason for doing this for pastes usually is to see whether the dispersion process has reached the required end point for that pigment. Probably the most common method in labs and plants is taking readings with a grind gauge, usually the Hegman type (ASTM D1210). Pigment dispersion quality in pastes and paints may be tested by one of several different techniques.
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