when to topcoat after epoxy primer?
Hello, I am new to the discussion forum. I am also new to auto painting. I am working on a car project that I would like to paint myself. I have chosen to use the PPG omni line of paint for my first attempt. It seems to be a good compromise beween quality and cost. The system uses a MP170 epoxy primer and the MTK acrylic urethane topcoat. According to the PPG product sheet I need to topcoat within 72 hours. If I don't get it topcoated before 72 hours expire I have to scuff the surface with sandpaper to get the topcoat to stick.
I have been told that a chemical reaction is taking place during this first 72 hours and, if topcoated within this time, the topcoat will adhere better. Do I understand this correctly?
So what my real question is: When is the best time to topcoat with this epoxy primer? As soon as it is dry to the touch? Wait an hour? Wait a day?
I tried to contact PPG but they haven't answered and the P-sheet only says within 72hrs. So if anyone is familiar with this paint system could you advise me?
I just found this forum and have learned a lot already!