Claude Monet once commented that”Color is my day-long obsession,joy and torment"-a sentiment that resonates with formulators of waterborne architectural paints who need to design base paints that can accept a variety of liquid colorants,enabling a paint line with the broadest possible color palette.With the advent of point-of-sale(POS)tinting systems,many paint manufacturers now produce only a small number of base paints to which the colorants are added at the store.This allows paint manufacturers and stores to manage inventories by stocking fewer materials,and it significantly decreases the amount of unused paint that goes to waste each year.However,the colorants used in POS tinting systems must have excellent compatibility with different base paints to ensure consistent,reproducible colors under all conditions.This remains one of the toughest challenges facing the waterborne architectural paint formulator today.Difficulties occur when additives used to stabilize the pigments in the colorant interact with additives in the base paint,causing loss of pigment stabilization and flocculation.This leads to an immediate or gradual color change that can be observed in a”rub-out”test in the laboratory.”Problem pigments"(like PV23,PBk7 and PB15:3)give rise to the most challenges with regard to colorant acceptance.This paper describes the mechanisms involved in colorant stabilization and,using chemical structure-property relationships,explains how specific surface active agents can be used within the base paint formulation to prevent destabilization of the colorant,ensuring that it performs as intended.
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