a charge content of 10 mole percent available from nalco company naperville ill usa examples 2 3 and 4 were performed to demonstrate that binders contained in the waste coating color were deposited onto the pigment or filler surfaces after the treatment samples of 20 80 mixture of waste coating color and fresh filler before and after the treatment described in example 1 were centrifuged at 1500 rpm for 15 minutes after centrifugation the supernatant of the untreated mixture was turbid while the supernatant of the treated mixture was clear the particle size distribution of the particles contained in the supernatant of the untreated mixture was shown in fig3 it is believed that the size of the particles is consistent with binders from the waste coating color 3 u03bcl of 0 1 nile red solution in ethanol were added into 3 ml supernatant from the centrifuged untreated mixture described in example 2 and the fluorescence spectrum was taken after subtracting the fluorescence from oba optical brightening agent contained in the solution there was a significant fluorescence emission as shown in fig4 the same experiment was also conducted for the supernatant of the centrifuged treated mixture described in example 2 there was no fluorescence detectable and the result was also shown in fig4 nile red dye emits fluorescence when it is adsorbed on a hydrophobic solid therefore the result indicates that substantially all the hydrophobic materials contained in the waste coating pigment were not in the supernatant after the treatment 10 u03bcl of 0 1 nile red solution in ethanol were mixed with 3 ml slurry of the treated mixture described in example 1 the fluorescence images of the particles were taken using a confocal laser scanning microscope with laser excitation at 488 nm and a 530 nm.