I am in the business of repairing woodwind and brass instruments.
Replating of parts is something we deal with on a regular basis.
On parts that need to be plated we do all the "prep" work, then we
ship the parts to another company to do the actual plating.

The chemicals used in plating (if you want more than just a very thin
short-lived plating job) are very nasty.  EPA regulations more or less
prohibit a small company from doing plating!

One thing I have noticed lacking in the discussion is this: the more
highly polished the base metal is _before_ plating, the nicer the final
product will look.  Not only should it be highly polished, but it must
be absolutely clean and free of grease.  The 'secret' is in the
preparation before plating.

John Miller
Saint Paul, Minnesota, USA