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From: ornitz@kodak.kodak.com (Barry Ornitz)
Newsgroups: sci.electronics,sci.engr
Subject: Re: Need information on Cu,Ni,Cr plating of 1m dia hemisphere
Summary: Not a good way to make this.
Keywords: electroplating,strike,copper,nickel,chromium
Message-ID: <1991Feb1.215650.13469@kodak.kodak.com>
Date: 1 Feb 91 21:56:50 GMT
References: <2867@oucsace.cs.OHIOU.EDU>
Sender: Barry L. Ornitz
Followup-To: sci.engr
Distribution: na
Organization: Eastman Kodak Co, Rochester, NY
Lines: 57

In article <2867@oucsace.cs.OHIOU.EDU> Bill White writes:
>1. Is it feasible to plate onto an aluminized mylar surface?  I know that
>it is possible to plate onto insulating surfaces *somehow*, so I would
>assume that plating onto an aluminized surface would be easier from the
>standpoint of conductivity.

Yes, it is feasible.  You will need an electroless copper to produce the base
layer, followed by a "strike".  Conventional acid plating can be used over
this.  The aluminized surface would be a hindrance and actually interfere with
the plating.  (Remember the electrochemical series when you consider what can
be plated over what.)

>2. Does anyone know where to get spherical aluminized mylar balloons in
>the range of 750mm to 1m diameter?  (if the answer to the above question
>is yes, of course)

I doubt it would be spherical enough.  

>3. Can anyone suggest any references on plating copper to a thickness of
>1/8 to 1/4 inch?  References on strike-plating onto aluminized surfaces?

Building up to this thickness will be next to impossible.  Grain growth and
leveling problems will be the killer.  Stress will also develop as the thick-
ness grows.  You should be able to get more information in something like 
"Modern Electroplating Handbook".  Getting above 10 to 20 mills is going to be
quite difficult.  See my comments above about aluminized surfaces.

>4. I assume it would be simpler to have some company finish the nickel
>and chrome plating (I actually don't know if I need chrome, so long as
>the nickel won't corrode I could just use nickel alone).  Is it practical
>to do this type of plating myself using University resources, or would
>it be easier to do this commercially?  The thickness does not matter;
>the surface condition does.

You could not do this yourself without lots of specialized equipment, chemicals,
and most importantly experience.

I really think this technique in general is a poor one.  I would look carefully
at spun aluminum or spun copper using wooden forms.  If you have to go the
electroplating route, consider plating over well-sealed wooden forms.  Use
something like polyester resin to seal the wood.  A number of plating houses
can start here.  If they can bronze baby shoes, they can copper plate this
form.  Strike solutions tend to be expensive, complex, and very poisonous.

Why do you always have such grandiose projects, Bob?  ;-)

					Barry

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|  ___  ________  |       Dr. Barry L. Ornitz          WA4VZQ
| |  / /        | |       Eastman Kodak Company
| | / /         | |       Eastman Chemical Company Research Laboratories
| |< < K O D A K| |       Process Instrumentation Research Laboratory
| | \ \         | |       P. O. Box 1972, Building 167B
| |__\ \________| |       Kingsport, TN  37662       615/229-4904
|                 |       INTERNET:   ornitz@kodak.com
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