The latest newsletter of the Color and Appearance Division of the Society of Plastics Engineers contained a noteworthy article that should be read by anyone involved in the coloring of plastics or coatings.  Bruce Mulholland of Ticona authors a technical article "Effect of Additives on the Color & Appearance of Plastics".  It can be found in the SPE CADNEWS Summer2009 starting on page 14 at:

http://www.4spe.org/technical-groups/newsletters/105

His opening salvo was right on target about how often color is just considered a necessary evil in the product development cycle.  His 9 steps of a typical cycle made me laugh, but sadly are all too often true.  The article goes on to describe in depth why color cannot be an afterthought in the development cycle. 

What I particularly liked was his explanation of the physics of light scattering and absorption and how various additives to a resin system will affect the color.  Equations and diagrams are used to explain how changes in the refractive index within the polymer system will change the color.  He describes the effects on color in different resin classifications and then goes on to list typical additives and how they affect light scattering and therefore the color.  Any color chemist who wants to understand more about these interactions with light and color would benefit from reading this article.  This article would also be of interest to anyone involved in the coloring of plastics-from designer and specifier to the development chemist and technician.  Even their counterparts in the coatings industry would benefit from understanding the principles described here.

While you may not always like what happens to a color formulation when you put it into a product matrix, at least now you can better understand what's going on and why.