“This is a hangover from a previous era. When most photocopiers used selenium photoconductor drums, there was a big problem with blue light discharging the drum, resulting in it not copying well.
This was resolved in the early 1980s by the adoption of either CdS drums or other photoconductors. Even those that continued to use selenium got around the problem by adding 5% tellurium and 10ppm chlorine to the coatings. These days, the only reason a photocopier should fail to copy blue writing is if there is a fault with it.”
From my clever colleague with special knowledge of this subject, Prit Buttar.
From me: if you want indelible ink, it is still India Ink, which is not easy stuff, and not usually found in black pens particularly ball points. If you want a form in monochrome (losing the information of colour) then photocopy it on one of the remaining copy machines that doesn’t print colours as colours. If you want it legible, computable, and available for mechanical checking and fault-free sharing, obviously print it off a suitable computer program.