[TheForge] Re: Cheap Autodarkening Welding Helmet.

[G.Watts]

  OK, as far as that goes with the UV, but welding throws out a bunch of
light in the blue spectrum, as well that may or may not be blocked by
polycarbonate lenses, depending on whether they're coated or not, and with
what.  Most cover lenses are not.  Many safety glasses do have coatings to
block a wider range of harmful wavelengths (www.uvex.com has a wealth of
info on the available coatings).  The CCOHS (Canadian equivalent of OSHA)
website at http://www.ccohs.ca/oshanswers/safety_haz/welding/eyes.html
states that:

"A serious concern is the "blue light hazard" which is the temporary or
permanent scarring of the retina due to its sensitivity to blue light,
around 440 nm wavelength. Blindness may result."

The specs that I have seen on clear, uncoated polycarbonate cover lenses
indicate that they block 99.9% of UV up to 400 nm.
So just because you're blocking the UV doesn't mean you're not toasting your
eyes.
I frequently weld at 200+ amps 8 hours a day and wear shade 3's under my
shade 11 hood...and I still look around periodically to see what else is
available.  Hope this helps.

George

<<<<<<<<<<<<<<<<<<<<<snip>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

If the front (clear) shield is polycarbonate, it absorbs 99%+ of the UV.
There's an OSHA spec that requires welding lenses to provide UV protection
at all times.  The instruction sheet that came with the helmet probably had
a paragraph that said to use only manufacturer-provided front shields, so as
to maintain the UV protection.

A quick go/no-go test for UV absorption is to look at a UV light source
through the lens/shield.  The light source souuld should appear dark.

>it is stopping the visible spectrum alright, but outside of that is
>there an easy way of verifying?   Regarding the sensitivity of the auto
>feature, it had two switches that adjusted sensitivity (high and low)
>and speed ( fast and slow).   I used it in the high/fast setting as the
>other settings were nothing like my sellstrom that I have gotten used
>to.   On the high sensitivity setting it tends to darken even on
>sunlight reflected off the bare metal, but I would rather that than the
>alternative.


You get what you pay for.  For hobby work, the inexpensive helmets are
perfectly adequate.

Ken
:-)



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