Painting

Talking about tach sheets. I notied othr day when Iorderd more SPI epoxy their thech sheet said to NOT apply over etch primer! NO way they said. I fabbed some patchs other day and had some etch primer handy and shot that over it to al it for now. better sand that off when my epoy primer get here! They scared me!!! I should call them and ask WHY. I have read before that epoxy primers vary and has something to do with acid in some of them. Don't know just curious.