I had applied Raptor bed liner to my 1974 Dodge p/u with a coarse roller and let it fully cure. Afterwards, I noticed some thin spots and the roller didn't get into all crevices of the p/u box. I decided to put a 2nd coat of Raptor on it, but the texture left from the roller was so coarse that I couldn't scuff it up with a ScotchBrite pad. I used the Adhesion Promoter and it seemed to work real good. The box looks phenomenal and the coating adhered real well.