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Chrome plating hardness: Is it only 4H pencil hardness maximum?

January 20, 2015

Q. Hi,

My company just developed a new chrome plated carrying case for our product, and we are very disappointed by how easily the plating scratches.

Our designer's original specifications were that the plating be NCVM [ed. note: non-conductive vacuum metallizing], with a pencil hardness of 6H. But in the development process, we found that NCVM tested out at only 2H. We were told by our mold supplier that the hardness of NCVM could be adjusted, but only between 1H to 3H, and that increasing the hardness would cause adhesion problems such that the plating would flake and peel off in the consumer's hands.

On the other hand, EP (electroplating) only gave us a hardness of 4H, and we were told that it cannot be adjusted.

So, we ended up settling for EP with only 4H hardness, and now we are having a lot of problems with scratched cases.

Our mold supplier insists that it cannot be made any harder. They say they have tested 4 different Electroplating suppliers with similar hardness results.

But, our original handmade prototype samples were NCVM, and are noticeably harder than the final mass production EP cases. To the point that if a prototype case and a MP case are kept in a pocket together the MP (EP) case will scratch but the prototype (NCVM) case does not.

SO, other than wondering if my suppliers are lying to me, I guess my questions are, what are typical hardnesses for EP and NCVM, can the hardness be adjusted, and if so what do I need to communicate to my supplier to get that done?

Daniel Henschel
Product designer - Shenzhen, China