What does your shop do if a customer wants a piece painted and not stained? Don't you use something like Kwik Sand to seal the grain?
(edited cause I had to take the kids to a dance, and didn't have time to type everything..:-)
i'm not the finisher, but if they want it painted, we build it, 180 it, Then I believe it gets primer white first to seal the grain, sanded with 320 after by the finisher - "don't sand through the primer whatever you do!" were the wise words spoken to me many years ago the first time I had to sand primer...(I'd hate to be a finisher, their job *sucks*:-) and catalysing enamel paint for the top coats.
the primer shows grain just fine with one coat, that's why I had to use so many coats, (trowelled <literally> on the celoset (pretroleum based wood filler) first, too..sanded with 120,150,180, primed, filled, 320, primed,320, primed,etc,etc..:-)
sorry,I ramble, what was the question again? :-)