School me on UV lights

[Silver Creek]

They do have other benefits...



And, for even more fun, shine one on a scorpion:



But don't spend 18 on one when you can get the same thing for a few bucks.

Ultraviolet (UV) light is a wavelength below 400 nm. Although it is commonly said that we cannot see UV radiation, humans can actually see from 390 - 700 nm. So we can see a bit below 400 nm. Notice that the we can see the purple light of the UV flashlight above.

If we could NOT see the light from the UV LEDs, how would we ever tell if the flashlights were on or off? We could not, so it is obvious to me that the UV wavelengths of the flashlights are in the "very near UV range," those wavelengths that just below 400 nm. UVA is 315 - 400 nm, well above the UVB range (315 - 280 nm) that causes snow blindness.

Our eyes are exposed to UVA and UVB radiation everyday in sunlight. Put some UV resin on a piece of paper and take it outside and it will cure from the UVA radiation in sunlight. So our eyes are exposed to UVA and UVB every time we go outside without sunglasses. My view is that you get more damaging UVA radiation from sunlight than you can ever get from a UV flashlight used to cure UV resin. I do not use any special eye protection.

These flashlights use "black light" LEDs that produce long wavelength UVA light. Black lights are commonly used in bug zappers and to identify fluorescent materials such as the special dyes on currency.

Wikipedia notes that, "Black lights are employed for decorative and artistic lighting effects, diagnostic and therapeutic uses in medicine, the detection of substances tagged with fluorescent dyes, rock-hunting, the detection of counterfeit money, the curing of plastic resins, and attracting insects....the low power UV-A emitted by black lights is not a hazard to skin or eyes and can be viewed without protection"

https://en.wikipedia.org/wiki/Black_light