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Can't find a level 14 shade any where local so far,
and the online guys are either out of stock or coming from over seas and can't guarantee delivery???
Anyone know of a place still selling level 14 filters, like the 4x5 welding shields or whatever???
I heard some guy claim you can stack a level 10 & a level 5, does anyone know if that's true????
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Yes. Stacking the filters is cumulative.
UV is my profession. Not letting it blind people is job one. My average 40" bulb burns at well over 20,000 watts with a surface temperature near 1000'C = much brighter than sunshine and we deal with it like that every day.
The problem with weldors' burn (That is what most in the UV profession call it) is that you DON'T feel it when you do it. 4 hrs later your eyes are scratchy, then you go to bed and your eyes get crusty when you are asleep. Tomorrow will be most unpleasant and then things pretty much go back to normal.
UV light is actually really fragile. Doesn't take much to mess it up. Even clear plexiglass will filter over 50% of UV hitting it.
The whole CD or floppy disc viewing is a bad idea due to material variations. Just put on a welding helmet and stare all day if it floats your boat.