UV light and halogen lamps
Posted by
Elliot Burke
on 1999-12-07 12:08:48 UTC
There are quite a few glasses that are transparent to UV, but it is
interesting that the various plastics used for glasses, both polycarb and
acrylic, have added absorbers that cut out everything below 380 nm (UV).
If all you are concerned with is UV protection, and you wear plastic lensed
glasses, you are completely protected from UV.
I have measured about 10 pairs of glasses, both tinted and untinted, in the
last couple of years, and have found none that did not block UV.
There are two reasons for this:
1. manufacturers want to limit their liability, so they include this
blocking but don't advertise it.
2. plastic without UV blocking degrades much more quickly in sunlight than
the UV absorbing type. It is hard to find sheet plastic that doesn't absorb
UV.
Elliot Burke
interesting that the various plastics used for glasses, both polycarb and
acrylic, have added absorbers that cut out everything below 380 nm (UV).
If all you are concerned with is UV protection, and you wear plastic lensed
glasses, you are completely protected from UV.
I have measured about 10 pairs of glasses, both tinted and untinted, in the
last couple of years, and have found none that did not block UV.
There are two reasons for this:
1. manufacturers want to limit their liability, so they include this
blocking but don't advertise it.
2. plastic without UV blocking degrades much more quickly in sunlight than
the UV absorbing type. It is hard to find sheet plastic that doesn't absorb
UV.
Elliot Burke