I remember that 30 years ago, my Office Manager would not buy blue highlighters because if you used a blue marker, whatever you highlighted would not show up on a copy. Don’t know if new technology has changed that.
Blue pages and blue markers were a thing in script writing too.
I knew a couple of local actors and heard them mention those things and learned.
I used to print out copies of controlled documents in blue ink for the same reason.
I remember that 30 years ago, my Office Manager would not buy blue highlighters because if you used a blue marker, whatever you highlighted would not show up on a copy. Don’t know if new technology has changed that.
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That’s an observation I haven’t thought of for many years, but now it comes back to me that the only pen to use for signing documents, which subsequently required copying was the black ink pen. I don’t know the technology in DEWs, but it may operate with lasers and there may be something unique about the light spectrum and the color blue.
It was common in the graphic arts field years ago to only use blue pencil on artwork borders, etc, for printing because Kodak Graphic Arts film didn’t register blue.