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From: (Don Wilkins)
Newsgroups: rec.crafts.metalworking
Subject: Re: Brass plating stainless or nickel silver?
Date: Tue, 12 Jan 1999 16:48:08 GMT

On 12 Jan 1999 02:25:08 GMT, (Kaehley) wrote:

>I have some photo etched parts that I would like to put a brass platin on vs
>just painting.  Is there an inexpensive relatively easy way to do this?

Inexpensive sort of. Relatively easy I don't think so.

An electroplaters handbook should give you some plating bath formulas.
The problem with any alloy plating is that the entire process is
controlled by a gentleman named Murphy.

Generally the two metals have different potentials where they like to
deposit. Platers compensate for this by loading up the plating
solution with one of the constituents, and/or by adding complexing
agents which bring the two potentials closer together.

The next problem is that you usually are plating an alloy with a
different composition than that of the plating bath. The composition
of the plating solution which you carefully adjusted at the start
changes as you plate. It is rare that you can plate where the ratio of
the two metals in solution is the same as what you want to plate.

Now if you are plating copper e.g. you can get some control over the
bath composition by using copper anodes. As copper plates the same
amount dissolves over at the anode and the composition of the bath is
reasonably constant. With an alloy all bets are off because just as
there are differences in the two metal's behavior at the cathode they
also don't behave the same over at the anode. It is not easy to get an
anode or anodes which will keep the bath composition constant.

If you are only going to plate a few parts it should be fairly easy
but if you want to use the bath over the long term it is not so easy
to control the composition of the bath and therefore the composition
of the deposit. Is it doable yes but you will need to do a little
research before you start. The electroplaters handbook is a good place
to start.

Now this sounds like more of a decorative or protective coating in
which case the composition of the plate may not make much difference
so long as it looks and acts like a brass.

If that is the case you  may get by with a preliminary test plate to
see if the color is OK and adjust the bath as needed.

Can you tolerate a copper plate, followed by a zinc strike, and then
sufficient heat to difuse the zinc into the copper. I don't have a
procedure. It is a WAG that it will work.

My guess is that you are going to find that a cyanide bath gives the
best plate.

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