I just redid my hull centrelines with flowcoat (by brush) after grinding out soft spots and reglassing in what is the first bottom job in years. I could feel the flowcoat becoming harder to apply but it was still tacky 24 hours after application. Any reason for that? Temperatures were from 16 to 24C.
Was that gelcoat? If so, either humidity got to it or it wasn't sealed off from the air for cure.
