To: "Fisher, Nick" 
From: Scott Rychnovsky 
Cc: atm{at}shore.net
Reply-To: Scott Rychnovsky 


Nick,

I have looked at the paper I cited previously.  The plating and etching
techniques are all wet chemistry and are not even electric plating.  Thus
the Al surface is cleaned, primed with a zinc coating and then plated with
a Ni-P coating.  The plated surface is then etched with nitric acid to
produce the black surface.

The overall process uses a number of cleaning and plating solutions, but
all of the treatments are "dip and rinse".  Overall it doesn't
look any more complex than the anodic treatment a number of amateurs have
used on aluminum.  I should note that the process is used directly on
aluminum, which is an attractive feature.  Details of the process are given
in the reference I cited in my last e-mail.

I am not sure where this would be useful.  The obvious application would be
to take Al tubes and blacken the inside of the tube with this process.  The
problem is one of scale: that 8" F6 telescope tube will require a
really big bath!  It would certainly be doable on a professional scale, and
it might make sense for people at astrophysics, for example, to treat their
tubes this way.  On an amateur scale, one could use it to blacken small Al
pieces like secondary holders and mirror cells.


Scott


>After a bit of searching the nickel and gold based low reflective coatings
>seem to be produced by complex industrial processes (vacuum deposition,
>complex etching etc.) so I guess they're not of much interest after all.
>


--
--
Scott Rychnovsky
srychnov{at}chem.ps.uci.edu
ATM Page: http://tlepage.home.mindspring.com/

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