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This was the very first question asked when
www.finishing.com went on line in 1995, and has been asked
again and again as the years go by.
You may want to consult the chapter "Metallizing
Nonconductors" in the Metal Finishing Guidebook.
There are five metallization
processes that I am know of; you will choose one depending
on the nature of the substrate and the end use of the
item:
- Probably the easiest to
understand approach is simply paint that contains metal
particles or flakes, usually silver or zinc. This is used
on, for example, surface-mount electronic components to
make them plateable and ultimately solderable.
- You can apply a spray of
colloidal conductive material, either carbon or metal.
Actually, this is not very different than the first
approach except that the particles are extremely fine,
and the process is designed specifically and exclusively
for the purpose of allowing fine decorative plating on
non-conductors. Acheson Colloids of Port Huron, MI is a
well known supplier, and offers a number of solutions in
their Aquadag
and Electrodag series.
- I'm not really familiar with
it, but there are the solutions designed for brushing
onto ceramics and then firing in an oven. The familiar
gold edging you would see on fine china is an example.
One supplier is Hawking International Ltd, The Stenders,
Mitcheldean, Glos, UK; they call their product "Liquid
Bright Gold".
- Two-part silvering solutions
are used for many different applications. You
simultaneously spray a soluble silver salt and a reducing
agent in order to reduce silver metal onto the item in
question.
- The fifth and most complex
method is the one usually done for plating on plastics:
after you etch the material to give it some tooth, you
dip it into stannous chloride or palladium chloride, or
both in sequence, and then use the seeds that you have
thus formed as the nucleating points for electroless
copper or electroless nickel deposition. This is usually
a high volume industrial process and invariably relies on
proprietary chemistries available from the major
suppliers like Technic.
- [Courtesy of a response from
Mitchell Heldt, 4/13/01, a 6th method is "I have vacuum
metalized glass. The method should work for bone or other
substances that can handle a little heat. Once a thin
layer of metal is deposited the surface adheres to other
metals. While the melting point of some metals is quite
high, when only a few atoms hit at a time, the heat is
easily absorbed].
It is important to remember that this is a carefully
honed art, and you certainly should not expect to get the
same kind of results in early trials as are achieved by
artisans who have been working for decades to perfect their
trade. You also need to realize that plating chemicals are
aggressive, and you will probably have to develop some
techniques with wax or lacquers to keep the plating
chemicals from attacking the organic materials. If the item
is important to you, don't take a chance trying to plate it
until you are really good. And, of course, consult EPA and
DOD regulations.
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