I really question if it is in fact zinc chromate, because it's purpose is to facilitate a paint to stick like grim death.
A light green color suggests to me that it is in face a teflon primer, in which case nothing will stick.
Put a drop of water on it, and if it forms a bead, it's teflon. If it spreads out and wets the surface, then it is zinc chromate, which by the way has a brown color.
Hope this helps.