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What is 'Brush' or Selective Area plating ?
Brush
plating is essentially electroplating. However instead of taking the job to the
bath of electrolyte, the electrode is taken to the job utilising hand held
equipment.
Origins.
There is no
doubt that an early plater, taking an article from the plating bath discovered a
blemish in one small area. Rather than stripping the article and re-plating, he
wrapped some cloth around a piece of copper wire, connected it to the anode,
then holding the article against the cathode proceeded to dip the cloth in to
the solution and swab the blemish blending it into the finished surface. This
'doctoring' left much to be desired and was primarily used as a touch-up method,
to make good burn marks or to cover an anode shadow. The deposit achieved would
not stand up to close scrutiny for either quality or thickness. This technique
still remains useful today and is often used in modern plating shops.
History.
For years
this 'doctoring' remained just that as it was incapable of control and lacking
in reliability.
In the late 1930's Georges Ixci devoted his very considerable talents in the
electrochemical field to developing a precise, controllable, repeatable process
for local area plating without the necessity of immersion in a bath of
electrolyte.
A number of key principles were established which still govern development work
carried out to this day :-
Deposition had to be rapid
High quality deposits
Precisely controllable
Effective over a range of voltages
Safe for manual use
Usable with portable equipment
Must be portable
Subsequent
licensing to England and America saw great leaps in it's commercial
applications.
Developments.
This then led
to three major developments and subsequent improvements :-
Plating solutions containing higher metal content and reduced toxicity.
Working tools to allow for the dissipation of heat build-up utilising high
grade anodes formulated to prevent contamination of the plating solutions.
A power source capable of precise and safe direction with devices to ensure
simplicity of operation.
As a
secondary issue these developments put the process in the hands of non-platers,
opening up the electroplating industry and it's applications.
Advantages.
There are many advantages of selective plating over more conventional means,
obvious ones would include, large or complex machines requiring only small areas
to be plated either for repair or protection, items too large for conventional
size tanks, or items requiring very complex masking or having parts which would
be damaged by immersion.
Time delays can be factored into the equation for removal of items particularly
if they are very heavy, very large or difficult to remove from the factory.
Transportation to and from the plating shop also adds to the expense.
There are many other less obvious applications like applying protective coatings
or highly wear resistant coatings to aluminium, stainless steel and many other
base metals.
One of the most interesting uses of selective or brush plating, is the
application of 'precious metals' such as gold, silver, platinum etc to surfaces
either to change the surface or repair worn surfaces.
This use is often referred to as ' Decorative Plating' and may be used to plate
gold onto surfaces that were previously silver, chrome, brass, copper, nickel
etc.
Major advantages of brush plating, particularly in the gold plating area,
include the ease and portability factor offered by self-contained systems
coupled with the ability to add wear resistant metals to the gold plating
solution.
Alternatives.
Why use brush or selective area plating?
It can be used 'on-site' without large immersion tanks, complex masking or
the risk of plating surrounding surfaces.
It plates to precise engineering tolerances and finishes.
It can be used to selectively build up unevenness or scored / scratched
surfaces.
It can deposit any thickness from a trace upward.
It has a relatively non-hazardous impact on the environment by removing the
risk of spillage / leakage from large tanks of chemicals.
Possibly the best description of the brush plating process was created by the
engineers at the Rolls-Royce Motor Company, who called it "The Precision
Engineer's Putting-On Tool".
Conclusion.
Precision
selective area brush plating has come a long way since George Ixci's first
experimental steps in the 1930's. Today the process is approved by Military,
Civil Aviation Authorities, Governments and is used in many areas of industry.
Gold Plating using the 'brush' process.
Brush
plating provides an excellent method for the application of gold to surfaces
such as car badges, taps, jewellery and many other items without the need to
dismantle or remove the item and send away to a plating workshop.
24 carat gold is a very soft metal and most gold jewellery contains other metals
to strengthen or harden the gold - hence the term 9, 12 or 18 carat. For
instance, 18 carat gold consists of 3/4 gold and 1/4 other [harder] metal.
Mobile Gold Plating
use a
solution referred to as 24 carat Hard Gold which contains Cobalt. Cobalt is a
very hard and stable metal and greatly increases the wear resistance of the 24c
gold, ensuring customer satisfaction -
and referral business.
The
appearance and durability of an item brush plated with
MGP
hard gold is
generally of a much higher standard than is possible with immersion plating.
Similarly, silver, copper, brass, nickel etc can also be applied using the
MGP
system.
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