Uh... I worked on volume production of automotive parts, and they were bare smooth steel before the paint process, and very etched dull gray matte surface after phosphoric acid bath before painting. It was a fairly strong acid bath for reduced cycle time, and also to eat off any scale from the welds before paint to have good rust resistance there. No sandblast. In fact, this is why gun barrels going through parkerizing need to first have both ends plugged watertight, to prevent etching the bore, it would have made the whole bore like a very worn barrel with "frosting" just in front of the chamber.

Bluing or black oxide finish, on the other hand, polished parts in come out blued and polished, no serious etch, although they still plug the barrels before bluing.