I use a heat gun all the time, but you DO have to be very careful. If you find a wrinkle or loose spot after you've doped the fabric, a heat gun is the only way to tighten it up ; if you try to iron it out, especially over a piece of sheeting or rib, the iron can stick to the dope and mar the finish. In either case, you want to avoid seams to prevent them from loosening.