I was adviced to try some Floetrol in my Pro Classic Acrylic enamel and it does work to give me more wet time and less brush marks. Does anyone suggest using it in the Pro Lock Primer? I am priming pre hung interior doors.
Floetrol is supposed to assist in preventing brush marks by extending the open time of your paint. With primer, you are going to sand it down before painting anyway, so brush marks really are absolutely no concern at all. Just put the ProBlock on as-is.