[Milsurplus] Crystal History Book and tips on etching

[Bob kb8tq]

Hi

… and instead of storing / measuring HF as a liquid (with all the associated
issues) you store a solid. 

Bob

> On Jul 31, 2022, at 9:21 PM, hwhall at compuserve.com wrote:
> 
> Mr. Google says: Ammonium bifluoride will react with water to form hydrofluoric acid.
> 
> Wayne
> WB4OGM
> 
> -----Original Message-----
> From: Bob kb8tq <kb8tq at n1k.org>
> To: Mike Feher <n4fs at eozinc.com>
> Cc: Brooke Clarke <brooke at pacific.net>; Milsurplus <milsurplus at mailman.qth.net>
> Sent: Sun, Jul 31, 2022 9:48 pm
> Subject: Re: [Milsurplus] Crystal History Book and tips on etching
> 
> Hi
> 
> If you are etching crystals in a modern crystal plant, the
> “go to” is a solution of ammonium bifluoride. It’s much easier
> to deal with in the required concentrations than HF.
> 
> Bob 
> 
>> On Jul 31, 2022, at 5:53 PM, Mike Feher <n4fs at eozinc.com <mailto:n4fs at eozinc.com>> wrote:
>> 
> 
> While in college I got a container of HF from our chemistry lab. It came in a plastic container as it would eat glass. I did etch numerous crystals with it. While I was not aware of the hazards, I did use some caution in using the stuff. 73 – Mike 
>  
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell NJ 07731
> 848-245-9115
>  
> -----Original Message-----
> From: milsurplus-bounces at mailman.qth.net <mailto:milsurplus-bounces at mailman.qth.net> <milsurplus-bounces at mailman.qth.net <mailto:milsurplus-bounces at mailman.qth.net>> On Behalf Of Brooke Clarke via Milsurplus
> Sent: Sunday, July 31, 2022 5:31 PM
> To: milsurplus at mailman.qth.net <mailto:milsurplus at mailman.qth.net>
> Subject: Re: [Milsurplus] Crystal History Book and tips on etching
>  
> Hi Dennis:
>  
> My reading of patent 2479286 is that after grinding, quartz crystals have micro cracks that propagate with aging and temperature cycling.  By using an HF etch the cracks are removed thus stabilizing the crystal for both aging and temperature (See Fig 6, 7 & 8 in patent).  The patent also includes a slide rule design (Fig 10) which, for a given frequency change and cut, tells you the etch time.
> https://prc68.com/I/Xtal.shtml#Bliley <https://prc68.com/I/Xtal.shtml#Bliley>
>  
> PS I worked in microwave semiconductors and they used HF.  Extremely dangerous stuff since it attacks humans in such a way that they are not aware of it.
> https://en.wikipedia.org/wiki/Hydrofluoric_acid#Health_and_safety <https://en.wikipedia.org/wiki/Hydrofluoric_acid#Health_and_safety>
>  
> --
> Have Fun,
>  
> Brooke Clarke
> https://www.PRC68.com <https://www.prc68.com/>
> axioms:
> 1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
> 2. Everybody, with no exceptions, holds false beliefs.
>  
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