In my experience ive noticed that rattle can self etch does a really excellent job as a bottom coat. As everyone is saying it's going to get sanded off reguardless so if worrying about adhesion issues with automotive paint later in the future is your worry I would honestly say it's no big deal and here's why.. The self etch is going to be sanded down with 180 on a DA and over the self etch the automotive painter will apply a high build primer.. This high build primer is made to cover and adhere to damn near anything.. After this step the painter will sand with 180 and then 400 for best results. Now since this high build primer is 2 or 3 part it would be 100% compatible with any automotive finish over the top and you more than likely would definitely not need to worry about any kind of wrinkle or shrinkage in the spray can self etch. Over the high build would be sealer and then your base. Definitely not in contact with any contaminants from the original spray can self etch. I hope this helps anyone else confused about the process, though everyone does have their own methods and techniques.