Plating Callipers

[jono]

I've stripped my callipers down for rebuild, new stainless pistons and seals, bushing the rear handbrake mech etc.

I intend to have them blasted then zinc plated.

Is it necessary to protect the piston bores and machined faced of the two halves before plating and if so how is this best achieved (for the faces I could simply re join them - will be fitting new bolts anyway).

Cheers

Jon