It seems nobody has written the definitive article on epoxy primer yet. I've read much conflicting info, here and elsewhere. After literally years of reading up on different types of primer I still am not clear on what to use and under what conditions. I swear by Extend and similar products (Rust Fix), but many confuse these with the wash-off phosphoric acid types. It seems that epoxy applied over Extend will cause an adverse chemical reaction. This explains horror stories you've heard. So looks like have a decision to make. Go with what I know works, or try something new, epoxy primer. To help me (and others) make an informed decision I have a question, very simple question: Can epoxy primer be applied over factory paint or is it exclusively for bare metal? I have been in contact with the manufacturer of Extend and they assure me their product works with everything BUT zinc based coatings, eg: epoxy primer. Have also been in contact with SPI which seems to be the preferred epoxy reseller here. Honestly they were of no assistance what-so-ever and never gave me a straight answer to any question. Instead they used scare tactics and some of the stuff they said I know is wrong. If I quoted what they said, you would think I made it up. It was that retarded. It seems they are just salesmen and of course push their own products. How they stack up to other brands is debatable. People who I asked who restore cars have not heard of SPI, so doubt it will be doing any business with them. If ever get this all sorted out, maybe I'll write that article which addresses compatibility issues with different restoration coatings since none really exists. I really took offense with SPI insisting that every other product on the market is garbage but theirs. How is that helpful?