I removed this residue with a Q-Tip dipped in 70% Isopropyl Alcohol which did not hurt the pigment. Though I tested a section of the red, first, with a needle dipped in the alcohol and there wasn't any reaction.

I've also been using the 70% solution on my orchids for the past 16 years to knock down white scale, thrips and a host of other pests without any problems... and I also dip my fingernails into the solution each and every time I return home... and wash afterwards.

ChipGuide image.