IFPEN-BL Clear Blue all-purpose UV pen ink can be used for marking almost any type of substrate with an invisible, permanent, highly fluorescent (UV) tag for identification and tracing. Ink was designed to working with pens but can be used anywhere you need a strong bright fluorescent ink.
This is the ink for the refillable ink pen! Bright blue in color under UV, and water clear under normal light. No need to dilute this ink!