[vcf-midatlantic] [OT] Early Kodak Photographic Copying Device?
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.
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
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
More information about the vcf-midatlantic