Most people assume it's purely from intaglio printing (a mechanical engraving process). But the real story is even cooler: that satisfying tactile bump comes from ultraviolet (UV) light - specifically, UV curing technology.
How does it work?
The anti-counterfeit ink on banknotes is not ordinary ink. It's a special photopolymer resin ink. During printing, a relatively thick layer of this ink is transferred onto the paper, creating an embossed‑like shape. At this point, though, the ink is still wet and semi‑fluid. If left to dry naturally, it would take too long - worse, the raised shape would collapse and blur, leaving no noticeable texture.
That's where UV curing comes in. A high‑intensity UV lamp shines onto the wet ink for milliseconds, triggering photoinitiators inside the ink. Instantly, a cross‑linking polymerization reaction occurs, and the liquid ink turns into a solid. The best part? There's almost no shrinkage during curing, so the original raised shape is preserved perfectly. What your finger feels is a micro‑relief "frozen" by light.
Why is it better than traditional drying?
Conventional hot‑air drying tends to form a skin on the surface while the inner layers remain wet, causing the bumps to deform. UV curing, however, happens from the inside out almost simultaneously. The energy is precisely controlled, giving the note not only a durable, crisp texture but also anti‑counterfeit features that stay intact for a decade of heavy circulation.
Next time you touch a banknote, think of this little "light magic"…
So that subtle bump under your fingertip is not just the skill of an engraver - it's a photochemical trick completed in a few hundredths of a second. UV curing makes anti‑counterfeit features literally "rise" from the paper.
- A small beam of UV light helps safeguard a nation's currency, and lets you feel the touch of technology.
