This Instructable uses UV LEDs built into a hat of your choice to reveal facial decorations drawn in UV security markers.Health and safety
I have been unable to find official HSE data on the use of UV LEDs near the face. Since strong UV light can cause a semi-permanent to permanent condition known as "welder's eye", I would strongly advise that anybody who uses this project does so with their eyes shut
when the LEDs are switched on.
This advice is from The LED Museum
:Most sunglasses and some prescription eyeglasses have some degree of UV protection already; to determine if yours do or not, aim the flashlight at something that clearly fluoresces (such as those neon green & orange stickers that occasionally show up on your mail, day-glow orange price tags, or painted portions of a blacklight poster), positioning the light so the object in front of it glows (fluoresces) brightly from the ultraviolet light. Then put the glasses between the face of the light and the target. If the glow stops or dims dramatically, the glasses are stopping the UV and you can use them as eye protection at least for short-term use.However, if the glow remains or dims only slightly, look for another pair.In any case, never look directly at the LEDs without eye protection - not even for a minute.Symptoms of UV exposure may not appear immediately; they can be delayed by 30 minutes to several hours. They can include a burning or "sand in the eyes" sensation, and a hazy look around light bulbs and other bright objects. Mild cases are self-correcting within 24 to 36 hours; however if despite my warnings you still stared at this light from close range for more than a few minutes, it might not be a bad idea to see an eye doctor and tell him you've been exposed to UVA radiation.DISCLAIMER: I shall not be held responsible for any damage or loss of eyesight arising from your use or misuse of the information on this page. Thank you for listening.
UV security markers are not designed for use on skin, so users should also check for sensitivity by applying the marker to the inner wrist and waiting 24 hours to see if there is any irritation or allergic reaction.