E-Coating, tools and materials

I’m trying to achieve the same, popular finishes of chocolate and
black black as seen as in tons of popular designer pieces
(Le Vian | Jewelry Lover’s Dream Come True etc). Our black rhodium
plating looks barely gray and nowhere near what I’ve been seeing -
true black. A technician at Rio said the secret process is E Coating
but he could offer no additional It’s frustrating to
see it all through the industry magazines but even the large
suppliers are unable to tell what the process is; let alone provide
the tools and materials for it. Can someone please help?

Our black rhodium plating looks barely gray and nowhere near what
I've been seeing - true black. 

We did this in class the other day, a brass ring was highly
polished, then plated with white rhodium… looked great.

We then tried the blacks rhodium plating solution… well made a
nice dark bluish, the only reason it didn’t go really black is that
the black rhodium solution is pretty much at the end if it’s life.

Regards Charles A.

These coatings are done using vacuum deposition processes (CVD or
similar process). The machinery needed to do this is terribly
expensive and requires highly trained engineers and technicians to
develop the processes needed and operate them. Most of these goods
are being coated by companies that specialize in these type of
coatings rather than the jewelry manufacturers themselves.

James Binnion
James Binnion Metal Arts

Our black rhodium plating looks barely gray and nowhere near what
I've been seeing - true black. 

I’ve found, using Rio’s pen plating version of black rhodium, that
you get the blackest color by putting on the bare minimum. It seems
that the longer you plate, the more it starts to get gray and
lighter and brighter. For the best black, use as thin a coating as
you can. I’m not sure why this is the case, and it may not be for all
black rhodium solutions, but at least for what I’ve used, with a
Rhodinette pen plater, that’s what I’ve seen. Also, pay attention to
the recommended voltages. Don’t go higher than specified for your
solution. Lower voltage may help. And be sure your articles are
properly electrocleaned before plating.

Peter Rowe

OK. Has anyone found a place who does a good job? Do they only coat
large batches or could we send a single piece every once in a while?