I always use hardener in my basecoat. (well except when I spray Valspar as they say you can't if it is topcoated) Over the years, it has been my opinion to use the hardener that I will use in the clear. I have used a dedicated basecoat hardener like Diamont BCH2 in Diamont base. Last week the PPG rep stopped by and said I should be using a "primer" hardener in my basecoat....I'm sure this has probably been addressed here on the forum before but I don't recall seeing it. Maybe Barry could chime in with his opinion? What is the best option for catalyzing base?