Family of inks, usually of pastel colours, manufactured with no black or grey colour, and which become invisible under some specific readers.

For those inks, we distinguish 3 uses:

• For optical reading: ink is used for printing small coloured squares, used as a frame, inside of which a black or blue hand-writting will me made. Then the reader which has a specific filter, will detect and read only the inside of the frame, but not the frame itself because of its filter.n  Optical readers are available from for example IBM, SCAN DATA, HONEYWELL BULL, FARRINGTON, CONYTROL DATA.
•  For check scanning: mainly used in the scan of Euro checks. The background of checks is printed with inactinic inks, which can be erasable or fugitive or standard. Bank scanners are numeric and they are adjusted for keeping in memory only the variable datas from the check. For the background of checks, it is essential that the contrast value of this background is superior to 60%.
• Black infra-red: those black inks are formulated in order to be transparent under infra-red of above 700nm. They are used for hidding for example a barcode, by their black colour, but this barcode is still readable under Infra-red.