UV LAMPS INVISIBLE INK
Uv ink is a special printing one giving off visible light (400-800nm) while exposed to ultraviolet light (200-400nm).
BLACK Infrared Ink
This means that, we could see the color, for the bar code reader it is transparent and will not be able to read.
BLACK Watermark Ink
Under the sun, we observation can see a clear pattern of the watermark,widely used in the printing documents.