Carl Cravens on wed 17 aug 11
Okay, so David says welding glasses aren't enough, and you need buy pricey =
didymium, but he doesn't have the time to look up all the references which =
prove his point. Sadly, I don't have the time either, but the spread of mi=
sinformation annoys me too much when people are spreading misplaced fear. =
"Your eyes are too precious to risk" is not a solid foundation for an argum=
ent, especially when, after doing the research, we'll discover that plain d=
idymium is *less* suited to this task than #3 welding glasses.
If you look at Uvex's line of safety glass materials (http://www.uvex.us/uv=
exlenstechnology.aspx?id=3D4178), you'll find that every single one of them=
blocks over 99.9% UV except one... the didymium lenses. Uncoated didymium=
blocks 80% of the UV spectrum naturally... but only 80% without special co=
atings that increase the price. Didymium is a naturally-occuring compound =
of neodymium and praseodymium... it is not a material specially-formulated =
for the glass-blowing industry, it was simply discovered in the 1800's and =
found to have a useful property glass working.
http://en.wikipedia.org/wiki/Didymium (Do note that this article has no ci=
tations or references. Finding clearly reliable information about didymium=
turned out to be difficult. I'm assuming that Uvex's claim that their did=
ymium lenses block 80% UV is typical of didymium, since it's a standard com=
pound... so reliable in its spectral filtering that it's used as a calibrat=
ion standard.)
The primary purpose of didymium in glass working is to filter "sodium flare=
," the visible yellow flame created when heating glass, so the glass worker=
can see what's going on. It just coincidentally filters the narrow band o=
f light produced by sodium flare without filtering the visible light around=
that band. Gas-welding aluminum creates the same sodium flare, and didymi=
um lenses borrowed from the glass working industry were used at one time un=
til they were *replaced* in the welding industry because didymium did not b=
lock enough IR. http://en.wikipedia.org/wiki/Oxy-fuel_welding_and_cutting
Electric arc welding produces a lot of UV... enough to causes "sunburn" to =
exposed skin (discovered from personal experience working with welders at B=
oeing). http://en.wikipedia.org/wiki/Arc_welding
Proper arc welding glasses block UV. They block IR. They have to, or they=
wouldn't be doing the job welders need them to do.
The glasses I pointed to earlier, the ones I purchased, are:
Uvex S1907 Skyper Safety Eyewear, Shade 3.0 Infra-Dura Ultra-Dura Hardcoat =
Lens
They are made of Uvex Infra-Dura 3.0 material. This material passes only 1=
4% visible light. Absorbs greater than 99.9% UV. Absorbs 91% of IR. Conf=
orms to ANSI requirements for protective eyewear.
http://www.uvex.us/uploadedFiles/ProductConfiguration/ProductLiterature/Uve=
x_Lens_Tech_Update2011.pdf
All of this protection cost me less than $15, and it provides superior prot=
ection for both UV and IR compared to didymium. The only thing it doesn't =
provide is filtering of soda flare, which isn't a pottery problem. They ma=
y or may not be ideal for making cones more visible, but that's not the iss=
ue under scrutiny.
Whether an electric, gas or wood kiln produces UV or not is a moot point, u=
nless you're using uncoated didymium.
I see no reason to buy expensive didymium glasses to view the inside of a k=
iln. Doing so will result in less protection than welding glasses unless y=
ou buy the more expensive ones with the right coatings to make up for didym=
ium's natural lack.
I'm open to being proven wrong... but if you want to disagree with me, take=
the time to provide references. When dealing with safety, lets deal in fa=
cts, not speculation, folklore, poor memory or wishful thinking. To deal i=
n anything else is pointless and needlessly time-consuming.
Now somebody owes me a beer. I'm thirsty after 1.5 hours of research and w=
riting. :)
--
Carl D Cravens (raven@phoenyx.net)
Hail to the sun god, He sure is a fun god, Ra! Ra! Ra!
Dale Neese on thu 18 aug 11
Carl,
we do appreciate your research efforts on the glasses and you do deserve a
standing ovulation and a cold beer... or three.
I don't believe that anyone wants to prove anybody wrong on group, but only
receive the most current and best factual information available so we can
make our own decisions and choices.
The protective eyewear I have is years old and I posted the info I knew at
the time. Point being is to protect your eyes, limit eye exposure time to
kiln radiation when checking cones.
Thanks!
Dale Tex
"across the alley from the Alamo"
Helotes, Texas USA
www.daleneese.com
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