Process control for thin organic coatings using fluorescence dyes

The fluorescence dyes rhodamine B and auramine O were added to a coating material based on hybrid polymers (ORMOCER®s) in concentrations of 10 ppm each. The fluorescence intensity of the auramine depends on the curing state of the lacquer while rhodamine is almost insensitive to this variation of the molecular environment. With the combination of both these dyes, the curing state as well as the thickness of the coating can be measured. Due to the low concentration the dyes do not degrade the properties of the lacquer coating.