IR-transparent and IR-non-transparent IR inks for printing

Transparent IR and non-transparent IR inks are a set of inks where the first one is visible to infrared readers (scanners) whereas the second one is invisible to them.

Both inks are black in the visible light but only IR-non-trasnparent is visible to IR scanners. They are most often used as a set of solutions hiding a barcode from the eyes of an ordinary user.

A barcode is printed with an IR-non-transparent ink (black in a visible light) on an already printed IR-transparent ink (also black in a visible light).

That way, a barcode is invisible to an ordinary user (both inks merge to create a black rectangle, but the barcode is visible under IR light, which makes it readable by the IR reader (scanner).