Black and White Mounts

[P3D Bob Aldridge <bob.aldridge@xxxxxx>]

There's been quite a lot of discussion about slide mounts being white
towards the lamp and black towards the lens.

It has been observed that the white side is intended to reflect the heat
back, but I haven't noticed anyone specifically observing that the black
side is designed to emit the heat that is absorbed. So the design is
actually quite good. Of course, if you don't use them properly, then
these functions won't work. But is that bad design? 

Of course, in the case of the RBT mounts, the white side is translucent,
so doesn't act as a "mask" at all. You need the opaque black side for
that. 

Personally, I think it's unrealistic to expect your mount to protect
your emulsion from projection. You have to use a properly designed and
maintained projection machine, and handle the slides carefully. 

Some slides entered for the Third Dimension Society Annual Exhibition
last year were slightly cooked by a Dual Hawk projector. Colin Clay
sorted out that problem - I'm not sure what he did to fix the projector,
but the machine that I use in London runs very cool. I've projected a
slide for SEVERAL HOURS without ANY detectable ill effects! Not even
perceptable bleaching...

Pat Whitehouse (well known for her natural history AV shows - e.g.
"Tribute to Handel") always mounted her slides in glass. These have been
in circulation for years, and have survived well, BUT I wouldn't like to
remount any of them. In many cases, the emulsion will have adhered to
the glass.

The moral is: if you want to preserve your slides in pristine condition,
don't project them! Make copies, and project those. Personally, I'd
rather project the originals in RBT mounts and RBT projectors. I don't
thing they'll come to any harm!

Bob Aldridge
Stereoscopic Society Projectionist
---
 * POW 2.0  0007 * ... An optimist is just an inexperienced pessimist!


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