Techy,I asked my chrome guy a question just like yours ,then I couldn't shut him up!!
I got a rear guard rechromed last year . After an indepth explanation of chrome plating , the history, and the story of why my guard needed to be done properly and not like they do in taiwan ,I just left the piece with him.
When I picked it up he started the story where he left off a month ago.
Basically he stripped off the ol' chrome then copper plated the piece and polished it,to fill the rust spots.
3 times. then chromed and polished to a mirror finish.
Some of the best money ever spent given the final product
Just give the people the parts and tell them what you're after ,it's that easy.