stripping hard chrome plating

Hi plating friends

I am doing hard chrome plating of engine valves on large scale.Have got large qty of peel off valves.Tried HCL stripping.But black smut appears in places other than chrome plated and finds difficult to polish & remove.Can I try reverse etching in alkali???

Please kindly advice me at the earliest.

RAJARAM

(FARADAY ENTERPRISES INDIA)