[TheForge] welding heat

Sun Aug 3 09:09:00 2003

Rick -

No, didymium glass is used to filter out something called sodium flare which is
a problem encountered by people working with sodium glass, primarily those who
make beads. By itself, didymium does not filter out either infrared nor
ultraviolet light. The spectral transmission chart shows a very sharp spike in
that very small range of wavelengths where sodium flare occurs.
The gold coating is to provide protection against infrared, which are the
wavelengths which will give you cataracts. However, the gold coating is very
easily scratched.

On the other hand, if you look at the transmission chart for welder shades #3,
they also filter out the wavelengths where sodium flare occurs (along with most
other wavelengths in the visible spectrum), as well as virtually 100%
protection against infrared. The #5 shades are better at the longest IR
wavelengths, but they're darker, of course.

I suspect the glasses you're talking about were called something "Blue".
Blu-blockers perhaps. I've seen them, and I didn't find them any different than
yellow shooting glasses, which help increase contrast by blocking the bluer
wavelengths caused by atmospheric haze. I didn't find them anything special,
besides the fact that they didn't fit my head.

All the best,

Bob

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Rick Crawford
Sent: Sunday, August 03, 2003 8:36 AM
To: [email protected]
Subject: Re: [TheForge] welding heat

Hi guys,

    Sorry to interrupt, but are these dydidium glasses the yellow colored
glasses that make every thing look like there is more light than there
really is?  I saw some of those a few years ago, but had no idea what they
were.  Are these glasses all they are cracked up to be?  What are their best
features?

Rick Crawford at Rafter Lazy C
Home of Rick's Forge and LEM the Wonder Mule
In the middle of Northern Illinois
http://www.rafterlazyc.com
[email protected]