Problems in z black plating of jewellery metals

A. Hi, Krishan.

Sorry, I am not personally familiar with the phrase "z black plating". Do you know whether this is a trade name or an acronym, and generically what the process is? Is it a blackening process that you are applying to the silver jewelry? In what way is it not satisfactory: not black enough, wears off too quickly, etc.? Thanks.

Regards,

Ted Mooney, P.E. RET finishing.com Brick, New Jersey