[alt-photo] Re: direct positive paper
photographeur at nerdshack.com
Sat Oct 23 21:10:22 GMT 2010
>I wonder what its intended purpose is, the high contrast sounds like
>a document copying paper although I don't know why anyone would need
>one these days.
>I have not looked at the specs, is it a reversal paper or a direct
>positive based on a pre-fogging and controlled solarization? The
>later is developed in a single step while reversal development
>requires two developments and a bleach step.
The contrast is not that high. It's intended for pictorial work, but
(I'm guessing) all attempts to lengthen the scale fell somewhat short.
It is processed in a single step, but judging by the poor keeping
properties of the latent image I wonder if the pre-fogging may be
done chemically (I don't know how to make a pre-flash with light any
more stable than a latent image). I saw some Russian literature
about a decade ago discussing a direct-positive technique based on
emulsions that were chemically pre-fogged.
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