The job epoxy primer does
Epoxy primer is the adhesion and corrosion layer. It is the right choice on bare metal, sandblasted panels and any substrate where long-term corrosion resistance matters more than build. It seals the metal and gives following coats something chemically grippy to hold.
Where it sits in the system
A typical refinish stack runs: degreaser, then putty for shape repair where needed, then epoxy or surfacer primer, then color, then clear. Epoxy is the foundation choice for exposed metal; surfacer (mid-coat primer) is the choice when you need build and sanding for surface perfection. Many jobs use both.
Do not skip substrate prep
Even the best epoxy primer fails over grease, rust scale or old failing paint. Degrease thoroughly, remove loose material, and apply to a clean, sound substrate. Durability ratings assume standard, correct application.
Sourcing epoxy primer with the rest of the system
Buy epoxy primer from the same supplier as your color and clear so the layer chemistry is compatible and one technical team answers for the whole stack. SANHE supplies epoxy primer alongside surfacers, plastic primers, putties and degreasers for exactly this reason.