Re: [ATM] Fwd: [Fwd: [atm_free] Effect of pH on polishingfused silica was Re. Session 24...]

[David Weinshenker <daze39@earthlink.net>]

Jeff Rowe wrote:
> You'll run into stuff you've never heard of before as
> well, below are just a few random choices, showing the difference in pH
> recomendations.
> 
>    1. Regipol 950 BB  Average particle size 1.2 u, pH Factor 6.5-7.1
>    2. Ultra-Sol 1000  Average particle size 0.5u to1u, pH factor 8.0-9.0
>    3. Cerox 1650  Average particle size 1.5u , pH factor 7
>    4. 50-D-05  Average particle size 0.7u, pH factor 8.0
>    5. Barnsite  Average particle size 1.4u pH factor 9.0-10     ( not
>       that you would want to use this)

I'd seen references to Barnesite being unavailable these days, but why 
do you say that one would not want to use it? I note [1] that it was used 
in the last stages of the final figuring of the 200-inch Palomar mirror, 
evidently chosen as a slow-cutting, controllable agent for subtle touch-up 
work on localized zones.

-dave w

[1] Florence, Ronald: "The Perfect Machine: Building the Palomar Telescope"
(HarperCollins, 1994), pp. 396 - 398
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