"ormula (b) preparing a second reaction mixture by admixing (1) the alcohol-substituted colorant, (2) a carboxylic acid of the formula R2COOH, wherein R2 is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, (3) an optional esterification catalyst, and (4) a solvent and heating the second reaction mixture to form an ester-substituted colorant of the formula and (c) forming a" . . . .