Low VOC water-borne colorant compositions with improved microbial resistance and method for assessing microbial resistance of colorant compositions

A colorant composition comprising:

• an alkyl-isothiazolin-3-one in an amount from about 25 ppm to about 200 ppm based on the total weight of components of the composition, having a structure
• where R1 is a linear or branched chain alkyl group having 1-8 carbons;
• and
• a halo-propynyl alkylcarbamate having the structure
• where R1 and R2 are H or linear or branched chain alkyl groups having 1-7 carbons, and where R3 is a halogen atom (F, Cl, Br, I, or At) in an amount from about 1,000 ppm to about 10,000 ppm based on the total weight of components of the composition;
• and
• a secondary amino-benzimidazole having the structure
• where R1 is a carboxylate or ester group in an amount from about 500 ppm to about 4,000 ppm based on the total weight of components of the composition;
• wherein the colorant composition contains less than 200 g/L VOCs;
• and
• wherein the colorant composition comprises one or more pigments and a carrier and is substantially free of a film-forming polymer;
• and wherein the colorant composition is a colorant for tinting a base coating composition.