Cheap UV Flashlight to detect/test sunglasses UV protection

[8steve88]

@Halo…

Does it really seem to be 365nm? Should have very little to no purple glow with 365nm.

There is purple/blue there but the beam fluoresces stuff very well and charges GITD items nearly instantly. Those are what I use UV for and it does them very well.

[keltex78]

Curious about this light; the description says plastic, and all of the SK-68s I've seen have plastic lenses. Based on djozz's testing here:

https://budgetlightforum.com/t/-/31542?page=2#comment-719507

...plastic lenses are quite good at blocking true UV emissions. I'm betting that the UV is being blocked by the lens and all you are seeing is the fluorescence from the low-level visible blue light that isn't blocked.

This would be cool if you could get a glass replacement lens for an SK-68 though...

[Hestbech]

Not all plastic blocks UV-rays. My clear lens Oakley sunglasses (Polycarbonate) blocks all UV. My prescription glasses (don't know what kind of plastic -but not glass) blocks almost none.

@DanielM

how do you test sunglasses with a UV flashlight?

Place a modern money bill under the Uv-light. You should see som patterns light up. Place your sunglasses between the UV-light and the bill. If the patterns dissappear, the glasses block UV rays. :-)

[DanielM]

@Hestbech

Not all plastic blocks UV-rays. My clear lens Oakley sunglasses (Polycarbonate) blocks all UV. My prescription glasses (don’t know what kind of plastic -but not glass) blocks almost none.

@DanielM

how do you test sunglasses with a UV flashlight?

Place a modern money bill under the Uv-light. You should see som patterns light up. Place your sunglasses between the UV-light and the bill. If the patterns dissappear, the glasses block UV rays.

Thanks, finally a proper response.

[MountainKing]

@8steve88

I don’t know if it’s been mentioned before but I’ve just had a delivery from FastTech, a AA, 3 mode zoomie @365nm, what the hell they thought you need modes for - high-low-strobe - on a UV light. It fluoresces everything it should so there’s 365nm in there somewhere along with visible light. Excellent for the price. 8)

UltraFire 1*LED 100LM 3-Mode Purple Light Zooming LED Flashlight $5.68, also available with yellow, green or blue LED apparently.
Not bad on the throw end but weak at the flood.

Is that UV? Does not say anything in the description….

[Halo]

It says 365nm. Though that seems to not be the true wavelength. Probably just around 400nm.

[eas]

For what it is worth, back when a worked in a lab, I took a couple pairs of cheap $12 sunglasses that claimed UV protection and ran a UV absorption spectrum on them in a UV/Vis spectrophotometer. They all met or exceeded their claims.