RE: [ATM] Why not metal mirrors? (was Beryllium)

["Ellen Mackenzie" <mackenzieconsulting@sympatico.ca>]

Hate to tell you Mel but nickel and aluminium are a really bad cobination -
- it makes a nice thermet bomb. It' really hard to find an inexpensive over
coating for aluminium. The surface prep is done with fluorides, very toxic,
and only a few materials are suitable. Copper is a good intermediate for
subsequent finish reflecting surfaces like chromium.

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Mel Bartels
Sent: Tuesday, September 14, 2004 9:53 PM
To: ATM Mailing List
Subject: Re: [ATM] Why not metal mirrors? (was Beryllium)


The late Tom Waineo sent me an aluminum substrate and grinding/polishing 
instructions.  Basically, as I survey the literature, the biggest issue is 
extreme warpage thanks to the differential expansion between the coated 
nickel and the aluminum backing.

Mel Bartels 

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