Chrome Plating Over a Rough Surface
Q. How does the initial surface roughness effect the outcome of chrome plating? Does it depend on the thickness of the plating? What about surface peaks and valleys -- will the coating always follow the
peak and valley or does it smooth them out?
A. Chrome plating does not smooth out peaks & valleys. Nor will it hide
scratches or nicks by itself.
For decorative chrome, parts are polished, then coated with a build layer of
bright nickel or bright copper/nickel to fill and level peaks & valleys
prior to applying the final thin "cap" layer of chrome (0.000020 - 0.000040
thick) hence the bright finish.
For hard chrome, base metal should be ground, smooth, uniform, with no sharp
edges. Typically, pre-treatment includes polishing, shot peening, glass bead
and/or grit blasting before plating. In the plating process, first step is
usually a reverse current chemical etch to enhance adhesion. Evidence of all
these pre-treatments can be visible in the finished layer of hard chrome,
but is seldom a cause for rejection. Thicknesses ranges from 0.0003 to
No substitution for proper base metal preparation in chrome plating. "Chrome
is a mirror or what's underneath"