Other than cleaning mirrors & lenses anyone any ideas on how to bring the
exposure level up to get black on light grey rather than black on almost
equally dark black background.
Anyone tried translucent thin but very white plastic sheet of some sort
overlaying the original. ?
Reducing the exposure masking increases the exposure but whites out the fine
details.
The paper has gone very brown from air bourne SO2/SO3 , neutralising the
paper with alkali improves things but tends to lighten the black image so no
further forward as far as contrast.

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Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/