Patent No. U.S. 7,160,371 B2
Ciba Specialty Chemicals has obtained a patent for a method of enhancing fluorescence of a marking composition comprising a colorant, which method comprises adding as an additive to the colorant, an organic pigment with enhanced fluorescence which organic pigment is treated with a surfactant selected from the group consisting of alkylaryl sulphonates and alkylphenol ethoxylates prior to addition to the colorant.