Amberlith wouldn't work but if you were lucky, if your art was at 100%, the ruby was clean, fresh, and decidedly well cut/created (few artists were that good) you COULD use them with Positive film, E to E to create film masks.I believe Rubilith masks were not suitable for reflected light photography, the shiny transparent Polyester base would reflect the light and mess things up.
They could have been photographed by transmitted light, but not at the same shot that the paste-up was taken.
In the early days of camera ready art (before filmsetters) you needed the art to make the film. Throw that away and make the film….out of what, exactly?
E upYou had your paste-up board with the text and other line art elements. (Jeez I'm old)
For photos you might have a box outlined on that paste up board. Then a ruby lith film would be attached to the pasteup with cut rectangles of red on the clear ruby lith film. When shot on negative film those red rectangles created clear windows surrounded by opaque black. That created the windows for the images (or screen tints) and that's what was trashed.
It's difficult to explain and unfortunately I haven't found any videos that show how paste-ups were done and how litho film was created from them.
A lost art.
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