[Boatanchors] Question for Metallurgically-Smart People

[Richard Knoppow]

    There are a number of web sites dedicated to amateur 
telescope builders. Its worth a search to see what is avaiable. 
Silvering telescope mirrors goes back a long way and is 
definitely something that can be done at home.
    Note also that is NOT necessary to plate crystals. They will 
work fine between flat electrodes. Plating can improve some 
characteristics but also makes tuning more difficult because the 
plating adds to the mass and changes the frequency. Many 
practical crystals were made with just electrode sandwiches. I 
don't have specific information but again a web search will 
probably find some. It will certainly find a great deal of 
history of the use and manufacture of quartz crystals for 
electronic purposes. Note that it was quite common for hams to 
grind their own crystals and some got into the crystal business 
out of their hobbies.

On 5/21/2020 11:39 AM, hwhall at compuserve.com wrote:
> The Jan 2020 issue of Sky and Telescope had a DIY article on silvering mirrors. There's a commercial product to do it now that is rather easy to use, the hardest part was apparently ensuring the entire mirror surface was adequately clean. Should be a snap for something an inch square or so.
>
> WayneWB4OGM
>
> -----Original Message-----
> From: Gary Peterson <kzerocx at rap.midco.net>
> To: boatanchors at mailman.qth.net
> Sent: Thu, May 21, 2020 9:19 am
> Subject: [Boatanchors] Question for Metallurgically-Smart People
>
> Back in my chemistry teaching days, there was a fairly urgent need for some half-silvered mirrors.  The ones that had been ordered were back-ordered.
>
> I prepared some Tollens’ reagent (the Internet will give you details).  I added formaldehyde to the reagent and poured it on glass plates.  This caused metallic silver to be deposited on the glass.  By experimenting with diluting the reagent and measuring with a photographic light meter, I was able to make some usable half-silvered mirrors.  This method should work for depositing silver on a quartz crystal blank.  Unless you have access to a laboratory, it is a bit involved.  Also, any leftover reagent must be disposed of properly or it may become dangerous.
>
> However, now that I think of it, I have two products at my work bench that might work.  One is GC Silver Print.  It is a paint for repairing broken circuit board traces.  It contains metallic silver.  I also have a Techspray, Trace Technologies conductive pen, which also contains metallic silver.  These products are not inexpensive.
>
> Gary
> KzeroCX
>
>
>
> “Does anyone here know a way to deposit a metal coating on
> the surface of a quartz crystal blank, without spending a gazillion
> bucks on a Phazer-Atom-Smasher-Hellbore vacuum chamber furnace?
> David Stinson”

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL