It is these mechanical art boards with the text pasted onto the base art board and the various layers of acetate overlays, and Ruby and Amberlithe that the pre-press technicians would shoot on those big vertical and horizontal stat cameras. Each layer of the mechanical art would have to be photographed in negative and then stripped together. Remember, I told you that I used to be a stripper. Tell your parents you have an ex-stripper teaching your class - see if that gets their attention.
The stripping process required taking multiple negatives of text, images and masks and assembling them together. Strippers and camera operators were very, very detailed oriented people that knew a lot about photographic "special" effects. The end goal was to get a composite negative for each color used in the design to make a printing plate. This is what the old guy in the movie Helvetica - who was it?, was talking about as being so difficult in the days prior to computers. The designer and paste-up artist didn't see what the design actually looked like until a blueline, color key and/or Match Print proof was made from the composite negatives. You had to be very good at visualizing a design in your mind and you relied heavily upon the marker comp. That is why comps had to be so accurate in representing the design. It was all you had to go by visually until the proofs arrived.
On Friday I'll bring in a small mechanical paste-up board to show you what a production art mechanical board looked like in the days before computer.