SF-06
UV-reactive fibres
Short fluorescent threads dispersed through the pulp, invisible in daylight and unmistakable under ultraviolet light.
UV-reactive fibres ×25
Specification
- House code
- SF-06
- Method
- Fluorescent fibres, seeded into the pulp
- Apparent at
- ×25
- Deters
- Substitution of visually similar commercial paper stock.
- The recipient’s check
- Under an ultraviolet lamp, short coloured threads light up, scattered at random and lying at every angle within the sheet rather than printed on its face.
Fibres are introduced into the stock before the sheet is formed, so they end up embedded at every depth and every angle, in a distribution no two sheets share. In ordinary light the paper looks entirely plain. Under ultraviolet, the fibres fluoresce in the colours they were dyed with.
The point is not the glow. It is the randomness and the embedding: the fibres are inside the sheet, they are visible from both sides, and the pattern they make was not designed by anybody. A printed imitation is a designed, two-dimensional, one-sided approximation of an undesigned three-dimensional fact.
Where it fits
Fibres are a machine-checkable feature, which makes them the natural companion to a watermark on documents that pass through a counting or verification desk — tickets at a gate, duty stamps at a bonded store, certificates lodged with a registrar. A single inexpensive lamp does the whole job.