Hi guys,
I'm looking into cadmium plating for some various parts on my M20, and wanted to ask a few questions before doing anything rash 
Is cadmium the preferred plating option for M20 restos?
Should I only be sending certain parts, or could I have them do odds and ends like bolts and washers?
Hi Brian..Cadmium plating was the correct finish for many of the fittings and fasteners on an M20...though it would take all day to list exactly which ones...A few parts were also dull chrome plated...
Cadmium plating is a 'barrel plating' process where all the parts are put into a rotating perforated drum to be plated....The platers, unlike with chrome plating, don't generally involve themselves in a lot of preparation work on the parts...
As a consequence I clean everything up by hand first, removing any damage/pitting etc...Then I run over all the parts on a rotary wire brush...
In this state I have found that there will be some variation in plated finish, depending on the methods you have used to clean up various parts..(if some are more shiny than others the finish will vary...)
To deal with that I finish everything to be plated by bead blasting it to give consistency...
Remember that plating (zinc/cadmium/chrome etc.) is just like spray painting...The finished result is only as good as the preparation that is done, either by you or by the plater...
Don't be tempted to substitute zinc plating for cadmium...Not only do the two look completely different but the zinc has a measurably shorter lifespan...
Check out the plater you are dealing with...Most of them have a minimum charge so you might have to get everything prepared and do it all in one hit to make it a practical proposition....Ian
email (option): ian@wright52.plus.com