plating, anodizing, & finishing Q&As since 1989
Visual Appearance of Sulphamate Nickel
Can visual appearance be used to identify if plating is really sulphamate nickel. I have read some plating house states that sulphamate nickel can be from Bright smooth to dull matt, how is this achieved? One of our local plating house told us that bright or dull depends on the plating solution, if we need matt, it is a property of the surface finishing on the machined part itself.
Therefore, if I need my finishing to be dull matt, is this a plating issue or a machining issue?
Hello, Sam. The bad news is that it is you who must understand what you want and how to specify it. If it is totally a matter of aesthetics, a matte look can be obtained by scratch brushing or bead blasting the surface before plating. However, sulphamate nickel is often specified for functional reasons, and the 'matte' plating may have as much to do with function (for example, more solderable or more ductile) as with aesthetics. But, no, I don't think that you can tell sulphamate nickel from other nickel finishes like Watts Nickel or Electroless Nickel by appearance.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
That means the matt appearance is mostly due to base material finishing? We do specified it as dull, soft and ductile, and it is very much for functional reason, we are putting conductive adhesive on them. And thus, when we had a lot plated by another plater, it turns out to be 'smooth and bright' even though no brightener has been added to the solution.
I read from letter no.29908 in 2004 responded by Mr Trevor Crichton that the plating process itself can also gives dull matte look though the article did not specify if there is any surface treatment.
Therefore if Mr Crichton is online, would you help to provide some feedback?
You can get matte or bright nickel out of a sulfamate bath depending on the impurities that have been dragged in. An excess of SNAP AM will definitely brighten it. Breakdown products of the sulfamate radical from temperature too high or from insoluble anode use leads to brightness. The current density used affects brightness. High aluminum can give a dark grey. So there is no good answer-- It depends.
If you want matte finish, specify that and it is up to the plater to provide it or pass on the job.
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