From: Bill Collins (photo@intrex.net)
Date: 07/16/01-05:42:19 AM Z
I'm sure a chemical etch would work, but here's what I did:
I got two pieces of glass (just ordinary window glass) of the size that I needed, put some automotive valve grinding compound between them and started grinding them together in a somewhat circular pattern. After doing this for a few minutes, I washed off the grinding compound, dried the glass and looked to see how uniform the grinding was. I then put more grinding compound on and put pressure on the areas that were still shiny.
The first time I tried this, it took about a half hour to get a good 5x7 ground glass. Later, I made a 4x5 in less than 10 minutes. The finish is a bit more coarse than modern camera glass, but that could be improved by using a finer grade of grinding compound, like the compound sold for making telescope mirrors. (600 grit, or so, in US terms. I think the 600 refers to the number of grains of compound per inch, so its probably called something different in the rest of the world) I used the valve grinding compound because it was easy to buy.
Of course, be careful handling the glass since the edges are sharp.
Bill
---------- Original Message ----------------------------------
From: Philippe Monnoyer <philippe.monnoyer@ulg.ac.be>
Reply-to: alt-photo-process-l@sask.usask.ca
Date: Mon, 16 Jul 2001 11:49:58 +0200
>Dear All,
>
>Would any one have a recipe for the preparation of a frosted glass for
>cameras ?
>I guess the treatment of the glass plate is a bath of fluorhydric acid and
>ammonium bifluoride ...
>I am searching for practical information,
>
>Thank you,
>
>Philippe Monnoyer
>Belgium
>
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