From: Joachim (joachim@microdsi.net)
Date: 09/24/01-09:11:24 PM Z
I think that one need not be overly concerned about the UV filtering
characteristics of glass for contact printing (and the same applies to
fluorescent bulbs for exposure) in connection with alternative processes.
This is not to say that UV blocking has no effect, but it appears to have
only an effect of significance on lengthening exposure - and the lengthening
may be an advantage more than a disadvantage. Joachim
> -----Original Message-----
> From: ken watson [mailto:watsok@frii.com]
> Sent: Monday, September 24, 2001 8:12 PM
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: UV Transparent Glass / $0.02 worth
>
>
> The only UV clear "glass" is made from quartz vs silica. The
> green color is
> Iron in the glass. It is possible to get Iron free glass that in
> either not
> green or much lighter green as seen from the edge.
>
> As for quartz glass ???? in large sizes
>
> ..-----Original Message-----
> ..From: Richard Knoppow [mailto:dickburk@ix.netcom.com]
> ..Sent: Monday, September 24, 2001 5:55 PM
> ..To: alt-photo-process-l@skyway.usask.ca
> ..Subject: UV Transparent Glass
> ..
> ..
> .. Some time ago I aquired a Morse contact printer. This thing
> was made for
> ..printing from aerial survey negatives and has 39 little Argon
> UV lamps in
> ..it. Not intense enough for alt use, but useful for slow silver paper.
> .. I got it cheap because the glass top had been dropped. I had a new top
> ..made from plate glass but its green and seems to have
> substantial blocking
> ..of UV (judging from the diming of the fluorescence of the brighteners in
> ..plain paper).
> .. I was told that clear glass was available only on special
> order and was
> ..very expensive.
> .. It seems to me that the UV transmission of glass is of interest to alt
> ..people. So, I am wondering what knowledge might exist on the list about
> ..kinds of glass available for, say, printing frames, which has better UV
> ..transmission than ordinary window or plate glass.
> .. The current thread on making a printing frame made me think of this.
> ..----
> ..Richard Knoppow
> ..Los Angeles, CA, USA
> ..dickburk@ix.netcom.com
> ..
>
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