primer/paint time

More bum information from a salesman - jeez! With the MP170 you have three days after applying the epoxy to apply your topcoat. See the manufacturer's tech sheet. If you go beyond the three days, you should scuff sand and reapply a coat of the epoxy prior to proceeeding within a new three day period. It's not as big a deal as it sounds if you miss the application deadline. The surface can be scuffed (sanded, if you will) with a 3M Scotch-Brite hand pad. They are flexible and can get around odd shapes easily. Best however to topcoat within the three days. If you are talking about sheetmetal that you are going to use a surfacer on, then just apply the surfacer within the time and you can let the remainder of effort on that part extend into the future as long as you like. You just need to get whatever is going directly on top of the epoxy applied within the three days for maximum adhesion. That's for the MP170 only. Other epoxies have different times. For example, PPG's more expensive DPLF epoxy has a seven day window and one of DuPont's epoxies has a 24 hour window.

Always get the product manufacturer's written instructions for use of products. They are much more reliable than word-of-mouth across a sales counter.

Rod