[TheForge] Vision damage and welding shields pt 2

Mon Jan 13 01:30:01 2003

My message was a response to the introduction of didymium glasses into a
discussion of the light intensity of the welding arc, oxy-acetylene welding,
plasma cutting, UVA and UVB. It seems people confuse the issue and think
didymium is the ideal filter medium, and it is not.

Didymium is good for one thing, and that is sodium flare.
Sodium flare is not, by itself, hazardous. It's a mere annoyance.
We have real hazards we must deal with, and didymium, by itself, doesn't
protect us from those hazards.

Just because we use borax doesn't mean we have the same requirements as
glassworkers working with sodium glass all day.

IR is the primary safety hazard (at least at the forge, it is), and what you
want is a filter which absorbs IR, as welder shades do.

If you'd taken my advice and checked out the charts, you'd see that a typical
welder shade #3 filters out 85% - 90% of the wavelength where sodium flare
occurs.
That's as good, or very nearly so, as some didymium or didymium-like glasses.

That's why I have no problem with sodium flare using my welder #3 shades and
don't have to resort to using didymium.
I also have UV and IR protection as well by using them.
(And I don't have to deal with a fragile gold coating on the lenses just
begging to be scratched.)

Argue if you must, but I still recommend you check the charts and do the
research before spending money on didymium glasses as a blacksmith.
Like I said, don't take my word for it....

Bob

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Dave Brown
Sent: Sunday, January 12, 2003 10:42 PM
To: [email protected]
Subject: Re: [TheForge] Vision damage and welding shields pt 2

<snip>
Borax is hydrated sodium borate (aka sodium tetraborate).   Ah!!! SODIUM!!!
is that what you wanted us to find?  (smile)

Dave Brown
>----- Original Message -----
>From: "Bob Rackers" <[email protected]>
> > If you don't work with sodium glass, there's no need for didymium lenses.
>None.

Ah, so didymium lenses will help for those of us who weld in the forge and
want to see past the sodium flare that rises as we reach welding temperatures.

Dave Brown
Heritage Smithing
Green Bay, WI
ABANA, UMBA, GoM, MODA, ARG

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