[TheForge] Vision damage and welding shields pt 2

[Bruce Freeman]

Gang,


I'm dubious of that gold-coating is the only way to stop IR. That makes =
little sense to me, though I'm not an expert in the field by any means.  =
IR will be absorbed by any material that can be heated by it.  The trick =
is to find such a matrerial that is ALSO transparent to visible light.  A =
google search shows many references to IR-blocking filters, but I didn't =
pursue the subject far enough to find out what they are.

 IR is light that is perceived only as heat.  You feel IR when you stand =
in front of a fire in a fireplace.  Typically, IR does not penetrate very =
far into things - it's absorbed by the first materials it encounters.  In =
the sciences, we have to use special materials to transmit IR.  Typically =
thin sheets of sodium cloride or potassium bromide are used for this.  =
These pass UV and visible light.  Glass is notoriously poor at transmitting=
 IR, which is why it isn't used.  All in all, it seems to me like it =
wouldn't be too hard to come up with a low-tech glass that absorbs enough =
IR to prevent cooking your corneas.  My guess is that any ordinary safety =
glasses would do the job, but don't quote me on that.

Bruce
NJ

>>> robi5515@bellsouth.net 01/11/03 08:31PM >>>
<snip>
> There are special coatings that can be added to safety glass to protect
you  from UVA and UVB, but the only protection from IR is by using gold
coated glass or plastic shield like the space helmets or foundry workers =
use.