Subject: Eye protection

From: Vance Burns <[email-masked]>
Date: Mon, 20 May 1996 12:37:30 -0500

There was some discussion earlier about safety glasses for the 
blacksmith and foundry man. I took that opportunity to do a little 
research. I can not attest to the value of this information, but here is 
what I have found:

Little if any risk from UV to the metal worker, however the physical 
properties of plastic filter out UV. All those UV block sunglasses in 
the drug store are plain low tech devices. You basically get UV 
protection gratis.

Didymium is still an unknown as to how much coverage, if any, is 
required. Didymium Glasses run under $40 and are available from several 
sources, and while inexpensive, often carry caveats about use with hot 
metal. Didymium is a hot filter topic in the camera world. Glass blowers 
are talking quite a bit about Didymium and the consensus is still out. 
Obviously, Glass blowers stare at flare auroras almost exclusively, and 
for extended periods.

I am still searching and have not come to a firm conclusion, and these 
are my opinions.

Some of the email I received on the subject follows. Since I didn’t get 
permission to broadcast these notes I have deleted their respective 
addresses.

Thanks
Vance
____________________
The glasses you need (dark green welders glasses) are available at
any welding supply.  The didieum glasses that glass blowers use do
NOT dim the light, they block the sodium yellow light totaly.  Since
there is not a significant amount of  sodium in metal there isn't
the yellow flare like you get with glass.
__________________________
Subject: Re: Safety Glasses
 
  This is a subject of controversy right now since some tests that
were made last fall have not yet been made public.  The problem is a
lack of information about UV risk for lamp workers using Pyrex-type
glass.  The risk is probably low, but not proven.

  One thing known is that didymium glasses are NOT sufficient
protection. The simple rule is that if your eyes show any sign of
watering, drying, burning or aching, or you have after-images when
working, you need darker glasses or mask.

  Lamp workers seem to buy from Wale Apparatus which has a variety
of glasses.

  Testing was done some time ago for furnace workers, which showed
that there was virtually no threat from UV and a considerable threat
from IR (infrared) at the furnace and when closely working very hot
glass.  These tests suggested that a #3 welding shade was minimal
and #4 (95% blockage) was preferred for furnace work.

  I prefer to use a plastic face shield because of its low cost,
full face protection from the heat and full vision.  I have used a
#5 (97.5%) for over a year and like it, though I admit it is very
dark.  I have become adept at moving it up and down.  I first
learned of the idea from a couple in Michigan who cut theirs off
just above mouth level so they did not have to flip them much.  I
have just bought a #4 which I am close to trying.  I buy my shields
through Welder's Supply.  The mount is a Jackson 170 S (not SB which
is more commonly stocked) using snaps and costs about $7.  The
shield is a Glendale Irex (Blue Diamond) 862 available in 4,5, and 6
shades; stocked by a company called Nasco, available on order by
most welding supply places.
___________________________ 
Subject: Re: Safety Glasses
You can get safety glasses from Wale Apparatus:
 
 Wale Apparatus - Scientific & some artisitic supplies
  400 Front Street
  PO Box D
  Hellertown PA 18055
  (610) 838-7047
  (610) 838-7440FAX
 
There may be better glass materials around nowadays.
A good eyeglass show may have catalogs describing
the features of various matials.  I still want to get
a good pair of flip-ups.
 
Be sure to look at how much IR blocking there is.
It's probably not a big deal doing flamework, but
using a glory hole can be nasty...

---

From: "[email-masked] 415.855.5707" <[email-masked]>
Date: Mon, 20 May 1996 11:15:36 -0800 (PST)

Just to throw another thought into the ring:

I have read that Didymium doen not filter out UV/IR light which would certainly
make it unsafe.  How unsafe would be a function of what kind of forge and how
long you start at it I suppose.

There is a niffty lens available from TM Technologies (916-292-3506) that is
designed for gas welding aluminum.  It is effective at IR/UV blocking test
equivilent to a shade #4 I believe.  It's real claim to fame is that is is
light colored so you can see and it is GREAT at blocking the yellow flare from
welding flux.  The flare is just not there anymore.

The only downside is the cost - these little beauties run about $100 each.  I
have one and really like it a lot for gas welding aluminum - I'll have to try
it at the forge.