Visit any automotive forum and you can't help but stumble upon a long running debate on which direct to metal product is better, etch primer or epoxy primer. You will hear all kinds of technical facts, personal experiences as well as flat out unsubstantiated opinion. Then throw in the thousands of products available for the job, each with their own recommendations, and you'll find yourself overwhelmed. But after the smoke finally clears the fact remains that both types of primers will give you successful results - if used correctly. The route you choose depends on the condition of the metal you're starting with, the time…