Fluorescent ink, it’s kind of transparent ink, often to be called invisible ink. Under irradiation 200~ 400 nm light, the invisible ink gives out 400 ~ 800 nm visible light, and the color can be red, yellow, blue, green. Fluorescent ink depends on the different irradiation wavelength, there are two kinds,
Irradiation light wavelength 254 nm, the ink is called short wavelength, Irradiation light wavelength 365 nm, the ink is called long wavelength, long wavelength ink can be irradiated by both 254nm and 365 nm light, but short wavelength ink only can be irradiated by 254nm light.
Invisible UV ink, under common environment, it’s transparent, under UV light, it’s can be seen as yellow, green, red, or blue.

Type and usage
long wavelength invisible ink
TYPE: Y4-100, transparent, irradiated by 365nm, change to green.
TYPE: Y4-101, transparent, irradiated by 365nm, change to red.
TYPE: Y4-102, transparent, irradiated by 365nm, change to blue.
TYPE: Y4-103, transparent, irradiated by 365nm, change to yellow.
Short wavelength(254nm) invisible ink.

Solution of invisible UV ink printing
Fluorescent ink is common invisible ink, usually to be used to print invisible logo, number , mark..etc.,and test tool is UV light.