Hi Mark, Pete is right, you need an old style hard wax. I sent an email to mer about this problem and they were great explaining modern wax's contain a chemical called "Naptha" that reacts on certain paints. They told me to strip old the old wax's off the paint using white
spirit or similar, but to test on an small area first to make sure it does not remove the paint They then told me to buy G3 professional supergloss paste wax, which i did. It did take ages to do but the results were fantastic... And then i had no more problems It seems this "naptha" attacks paints at random as i have used mer for many years with no problem. I dont think colour matters as my car was light blue. I hope this might solve your problem. I dont think the G3 finish will solve the problem? But you could try emailing Farecla and ask if it has "naptha" in it. Keep us all posted
Tony.