I have just started tear down of my first game (Fish Tails) and I will spend a lot of hours tumbling, polishing and buffing all the metals in the entire game. Since these are made of iron (basically), and have surface corrosion now (mostly just white), they will pick this up again after some time
I have seen that some of you guys are sending parts out for surface treatment (Chrome, I guess), and I'm considering this as well. Depending on cost, I need to determin how many parts that will get this royal treat.

What is your experience of the durability of tumbling/buffing on assemblies on the playfield and under the playfield?
When you send parts out for surface treatment, do you send 100% or how do you pick the parts to go?
Are there any other ways of surface protection, wax or clear or what have you? Experience from this?

Sorry if this is a subject that been depleated already, but couldn't find much by searching on "corrosion"...