UV marking pen - only visible under blacklight (UV) – ZEGZUG

This is a very cool trick for upper making or as a matter of fact everywhere where you have to make materials. The mark is not visible by eye, but it really shows a lot better with a simple blacklight (UV). Get these and forget the regular silver pens! Comes in packet of 3.

DirectGlow Invisible UV Ink Marker Pen with Ultraviolet LED Keychain Blacklight : Office Products

These compact sized UV blacklight reactive invisible ink markers by DirectGlow use high quality semi-permanent invisible ultraviolet ink. Each marker

DirectGlow Invisible UV Blacklight Reactive Ink Marker with Separate UV LED Light

UV 10 Visible with Ultraviolet Black Light

Thicker fluorescent Invisible Blue UV Marker MAX-C0

Opticz Invisible UV Blacklight Reactive Fine Tip Ink Marker – DirectGlow LLC

0.7 mm marking pen, UV Set of 3 - Heat makes this disappear! – ZEGZUG

Bag of Six Units of UV Invisible MAR-C06 Security Marking Pen

Dual invisible blue pen with black marker on the other side

Opticz UV Blacklight Reactive Invisible Ink Markers Security Kit

Opticz Blacklight Reactive Invisible Blue Ink Industrial UV Marker with UV Light : Office Products

Opticz UV Blacklight Reactive Large Tip Invisible Ink Marker, Blue