I'll try to explain it. I was a janitor in the college press years ago.
1. A slide was separated by projecting through magenta, cyan and yellow
filters onto negative ortho (b & w) film the size of the final picture.
2. Another separation was made just for the black areas.
3. Each color separation was taped to a large piece of thick paper
(layout) with holes behind each separation making four (4) separate
layouts for each color photo.
4. All the print type was shot on neg ortho film using halogen lights
and a camera that was big enough that, in our press, the photographer
could walk into the camera back and attach film to the camera. All the
ortho negatives were spotted to fill bubble holes in the black areas and
also added to the layout with the black separation.
5. Each layout made up (if I remember correctly) a 16 page part of a
magazine or book called a signature.
6. The back side of each page was also made up and had to match the
front of each page.
7. Each layout was then superimposed in front of an aluminum sheet that
had chemicals on one surface.
8. The layout was "burned" into the chemicals using a vacuum table and
halogen lights, then developed somewhat similar to film, except it was
all done in room light on a wet table using chemicals poured on the
plate and sponged around. The developer was red in color and made me
feel real perky the rest of the day <g>
9. The four different aluminum "plates" were attached to four separate
presses and the paper was run through all of them. Of course,
everything had to be aligned!
10. Ink was floated on a thin layer of water onto the plates, only
sticking where the plate had been etched by the chemicals.
11. The ink was transferred to the (usually) web of paper by direct
contact with the aluminum plate that was on the spinning drum.
Mike can give probably a clearer explanation of the process and how much
of that process is still happening. My recollections are from the early
'70s and might be blurred by time, age and the chemicals!
Gregg
Acer V wrote:
>
> How did mags publish images back before computers and scanner?
>
> /AV
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