Most UV flashlights use 395nm, which emits a visible purple glow. We use 365nm because it produces almost no visible light while triggering a much stronger fluorescent response. This allows hidden markings to appear sharply, even in less-than-ideal lighting, without drawing attention during use.

We use a permanent, UV-reactive ink designed to remain invisible under normal light. It does not fade or leave a detectable residue, ensuring markings stay hidden until intentionally revealed. When exposed to 365nm UV light, the ink fluoresces cleanly, providing a sharp, readable display only when you need it.

We chose 100% cotton, acid-free archival paper because it resists yellowing, brittleness, and ink bleed over decades. Standard paper degrades, risking data loss. These fold-over cards preserve the integrity of the ink and its fluorescence, ensuring your hidden markings remain intact for long-term cold storage.