Heres another quandry.... All PPG and Sikkens literature state that you MUST use their catalyst and reducer. I am sure that they are trying to keep the money stream flowing in their direction. I am also sure that all other higher line products want you to use their complete line of products as well. My point is: I have mixed brands several times and have yet to have any adverse affects. I dont think that I have been lucky either. I have never used Lacquer, everything has been medium to high quality enamel or urethane. I have mixed small amounts of base coat in with single stage to extend out the mix, and I never had any problems. The paint supply guys I have spoken with play the same tune as the Tech sheets, but they must know that you can use Omni reducer with PPG paint or Nason clear with PPG catalyst... and so on. I use the matching products as recommended but always have stuff left over. I have tested the interspecies mixing on spare fenders, hoods and whole cars without any wrinkling or lifting of the paint. Anyone else?