Q. I am engaged in color measurements for my company. I was wondering if the particle size of the resin can affect the tinting strength of a colorant. For instance, if the latex used in a coating has a larger particle size than normal, and the same amount of colorant is added, would we see a difference in the tinting strength? R.M.
A. I can’t imagine how the size of the latex particles would affect the tinting strength of a formulated coating. Tinting strength is dependent on the ratio of the volume of pigment to the total volume of resin in a formulation. It doesn’t matter if the resin system is continuous or discontinuous. If you are seeing any color differences, I’m sure they are caused by other factors,.
On the other hand, pigments of different particle sizes could have different tinting strengths. It is well known that they can also produce a difference in apparent color in a cured film. Actually, pigment volume concentration, oil absorption, packing volume and agglomeration are interrelated and could account for differences in tinting strength. The same can be said for extender pigments in the formulation. These factors can also affect the hiding power and gloss of the cured film and therefore the apparent color. However, since this is not the forum for a course in paint technology, we’ll leave it at that.