Back in the 1970s my father self-published a newsletter, and I'm trying to figure out what the printing process was that he used.
He laid everything out by hand (of course) and then there was a step that looks like a photographic negative and another step (not sure which came first) on a metallic sheet with maroon-colored text.
What process was he using?
You're describing offset lithography. The maroon (and silver) metal plate was the actual printing plate made by a photomechanical process in a process camera then in a contact printing frame 1:1.
In the printing press, the plate is wet with a "fountain" solution. The silver part (zinc-coated aluminum foil) remains wet. The pink parts are water-resistant so the water won't stick but the ink does. (Oil and water don't mix.) Then, the inked plate is pushed against a soft rubber (blanket) roller. The ink is transferred to the rubber which is in turn pushed against the paper.
The ink image (which is fragile) is "offset" onto the "impression" roller (blanket) which contacts the paper. This is done to avoid the abrasive effects of rubbing rough paper surface (thousands of times) against a thin foil ink-carrying printing plate.
That's a version of how printing used to look between lead type and word processors.
You'd have someone type up the copy on a typesetting machine, which would produce long strips of copy in a particular letterface at a specified pitch (point size). The paper was not quite vinyl, but definitely sturdier than paper, and coated so it was a bit waxy.
You'd use an Xacto or a razor to cut your strips into the desired column length and paste them (using glue or a wax) onto layout pages with a grid. When I was doing it for a newspaper, the layout pages were, I dunno, maybe 40" wide by 24" deep to accommodate two 17"x22" sheets of newspaper, and the grid lines were printed with what was called non-reproducing blue (or non-repro blue). Photos were printed and pasted onto the grid page the same way. A rule or line was a literal roll of stickers with a rule printed on it.
The idea is that these pasted-up pages were brought into a darkroom, and a special camera took a photo of them. The non-repro blue didn't, you know, reproduce, so the camera only took a photo of the copy and photographs. This was then turned into a negative. Why your negative has lines you can see I can't say. It might be a negative from a different type of camera than we used. The red tape is the original masking tape, called rubylith, because it covered or "masked off" things you didn't want reproduced. It was a semi-opaque dark red plastic, either tape or sheets, that you used to cover anything you didn't want to the camera to pick up — sort of the opposite of non-repro blue.
The end negative was used to print the final product.
Let me be specific. That is no printing process, that is a pre-press process, so the printing process or press comes after these.
And as already stated by my colleges, the printing process is offset printing. (I will leave the lithography term for later)
Some of those steps can still be used today. Let me explain a bit.
A. The first step is almost entirely replaced now. Although you can have artwork drawn or painted, the layout is done on a computer.
B. The second step is negative. A lot of printing processes have a positive-negative-positive sort of play. The current process goes directly to the plate (Direct to Plate) (1) But negatives can be used still to some extent, for example on a small print shop or when the owner of a small business prefer to store the negative to be printed later. But as Direct to Plate is so cheap it is not common anymore.
The orange paper and the red transparent tape was used to, either correct parts of the layout that had a mistake on the original and detected after photographing it, or they were used to re-use some parts; a header, a footer, some logo, etc. The orange paper and the red tape were cheaper and faster than making a negative again.
It also was to assemble different types of negatives, mainly screened and not screened. (2)
C. That is a plate. The plate is the connection between pre-press and press processes. It is installed on the offset machine on one roll and this image is transferred with another rubber roll to the paper.
The pre-press process was:
Assembling the original, cutting and pasting on a board (positive).
Photographing it with a large camera on a large high contrast film (negative).
Making a contact transfer, a sandwich between two glasses with the plate with photo-sensitive stuff, and the negative inside to transfer the image (positive)
(1) A "Direct to Plate" - Jumps directly to the plate. From there, the printing process is basically the same.
(2) Photos needed an additional step. They were photographed but a "screen" was placed just before the negative, so the negative, that can not capture shades of gray had different sized dots to simulate the shades of gray. Screening is still done today but on the computer.
I left the "lithography" word aside, because, although it is commonly used next to "offset" it is a term to denote a detailed a precise variation of offset. But there are some primitive offset machines, that print small 1 ink flyers that have no precise registration, but they are still offset. And the same process can be used on big rotary presses.
Also, the original lithography process was making a greasy drawing on a big flat polished unporous stone (did the "litho" prefix ring any bell?), wetting the rest and then printing a paper with an oil-based ink.
The term also references a yes-no image. Either you have it or you do not have it. For example, a normal photographic film can capture different shades of gray, where a litho film makes the image so contrasted that it shows as black or white image.
