Fluorescent Security Ink
Definition
An ink visible only under UV illumination at a specific wavelength (typically 365 nm), used to print denomination numerals, flag motifs, and serial elements that verify authenticity under UV examination. Central-bank-specification inks not available commercially.
- Visibility
- Visible only under UV illumination
- Typical wavelength
- 365 nm
- Printed elements
- Denomination numerals, flag motifs, serial elements
- Sourcing
- Central-bank-specification inks not available commercially
Common questions
Why is the unavailability of the ink to the public an important part of the security feature?+
Because the specific formulation is restricted to authorised printers under central bank contract, a counterfeiter cannot simply buy a matching fluorescent ink on the open market. Any substitute ink used will fluoresce a different colour, intensity or under a different wavelength than the genuine feature, which is what an examiner checks for.
What does an examiner actually compare when checking fluorescent security ink under UV?+
The examiner compares the colour, brightness and precise location of the fluorescing elements against a known genuine specimen under the same UV wavelength, since a counterfeit may show fluorescence that is close but not an exact match, or is misregistered relative to the printed design.
Can fluorescent security ink be confused with the fluorescent whitening agents found in ordinary paper?+
Yes, this is a common pitfall. Genuine banknote paper is often deliberately formulated without optical brighteners so it does not fluoresce overall, making the deliberate ink elements stand out distinctly. A note printed on ordinary brightened paper can show a broad fluorescent glow that an untrained examiner might mistake for a security feature.
Related terms
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