Invisible Ink

Invisible ink is a special ink that cannot be seen with the naked eye under normal lighting and that glows or reflects only when irradiated with ultraviolet (UV) or infrared (IR) light. There are types such as fluorescent ink, UV ink, and IR ink, and each responds to a different wavelength band.

In the anti-counterfeiting of QR codes, invisible ink is a powerful means. By overlaying an authentication QR code printed in invisible ink on product packaging, separately from the ordinary QR code, genuine products can be distinguished from counterfeits. It is a two-layer structure: what consumers scan with an ordinary smartphone camera is the QR code on the surface, and what manufacturers and inspection bodies scan with a dedicated reader equipped with a UV light is the invisible QR code.

Invisible ink is also put to use on the design side. On works of art and luxury brand products, a visible QR code can spoil the beauty of the design. If you print the QR code in invisible ink, you can embed information without changing the appearance at all. It is also applied to judging the authenticity of appraisal reports and certificates, and it is based on the same principle as the anti-counterfeiting technology of banknotes.