[vcf-midatlantic] [OT] Early Kodak Photographic Copying Device?

Jeffrey Jonas jeffrey.scott.jonas at gmail.com
Wed Feb 20 04:22:10 EST 2019

Before photocopiers & laser printers were ubiquitious,
there were many curious methods of duplication.
See: https://en.wikipedia.org/wiki/List_of_duplicating_processes

1) if you have a paper copy that's a B&W negative,
it is probably a Photostat. I found several photostats in my dad's papers.

Both Rectigraph and Photostat machines consisted of a large camera ...
After a 10-second exposure, the paper was directed to developing and
fixing baths,
then either air- or machine-dried. Since the print was directly exposed,
without the use of an intermediate film, the result was a negative print.

2) I once salvaged a Thermofax machine.
It was a box of BRIGHT lamps and a heated roller.
No chemicals required.

3) I once had a little darkroom kit with a contact printer
which was a tin box with a light bulb inside,
a glass top with hinged top.
The paper was developed by inserting it into a plastic gadget
where a crank turned rollers (via gears)
dunking the paper into 3 consecutive chemical trays.

4) The way these relate to computers & electronics:
several of these processes were used for chart recorders
and "oscillographs" (oscilloscope where a light beam was
bounced by moving mirrors onto a screen, or film).
High resolution charter recorders avoided pen lag & overshoot
by using a galvanometer and light beam onto light sensitive paper.
I think HP used IR onto heat-sensitive paper
similar to today's receipt paper.

-- jeff jonas

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