Our bright chrome tail pipes are fine but our brushed chrome ones fail salt spray

We supply the tail tipe for automobile, mostly in shiny chrome plating, no corrosion resist problem.

Now we have a problem for a brushed chrome tube. the plating request on drawing is simple: flashed & brushed. we received customer sample in dull brushed chrome color with polishing textures.

Our process for the plating:
tube make---100 grit polishing---chrome plating
problem: effect is not dull enough, and did not pass the salt spray test.

From the plating spec., the low gloss finish should be done before plating, but our customer told me yesterday the way they currently do is:
tube make---chrome flash---brush finish

I don't understand why the brush finish is after the plating, why different with plating specification? is there any other chemical method for brush finish to be dull looking and stronger corrossion resist?

Dear Yan.

Do you mean buffing?

Generally it is done to increase the crack count of the plating which increases the corrision resistance and also traps oils between the cracks for lubrication. Is your chorme decorative or for wear resistance?

Best Regards