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Infrared light


#1

I’ve been following this thread waiting for someone to talk about
calobar lenses and nobody has of yet. I have starting enameling
quite a bit and was worried about my eyes. I got some UV glasses at
a welding supply place but I still didn’t feel like it was doing
what I needed. I talked to Coral at Enamel Work Supply. She said
that there was a big debate in Glass on Metal magazine about the
best glasses. Some people thought kolabar lenses protected the
best, but after the study it was determined that calobar lenses
protected your eyes from the specific ultraviolet light that a kiln
puts off. So off I went to the eye Doctor to get some calobar
glasses in my perscription. They didn’t have a clue as to what I
was talking about. They told me I needed didium (not sure on
spelling) glasses, like welders or glass workers wear. I called
Coral and she said no, the torch puts off a differant light and
didium glasses would not work. So the eyeglass people had to get on
the internet to hunt these down. Only one company in the US makes
them in perscription lenses and that’s American Optical. There a
place in Portland but I talked to them and they couldn’t do
perscription. Anyway they cost me about $300. They’re a dark green
but I can see very well with them. I could just kick myself for
getting them in the perscription of my bifocals. Because they’re
for reading. I wanted to use them for soldering also, but I can’t
get close enough. But I found I could put some walmart cheaters on
in front of them and I can get up close to see. I bet I’m a site
for sore eyes, it gives “Four Eyes” a whole new meaning! And while
I’m rattling on… About the MRI My husband was shot in the
head and he has a plate in his head. It’s plastic but it’s wired on
with stainless steel wires. They don’t do that now. But anyway,
The doctor said that it could possibly cause the plate to move. So
he asked him if he would do it if the tables were turned. He said
no and so did my husband.

God Bless you
~Poppy~
www.jewelrybypoppy.com


#2

Can I make a correction to your comments? Kilns do not emit UV, they
emit IR. This is a common misconception. UV is at the blue end of the
spectrum, and in order to generate any amount of seriously damaging
UV, temperatures have to be in excess of 5,000 degrees.

IR on the other hand is heat energy, which the kiln has plenty of.
Calobar, and its cousins, the welding shade lenses, are excellent IR
filters. My company manufactures a Calobar look-alike that we call
AUR-99. It is available in shades 1.7, 2.0 and 2.5. These filters cut
visible light transmission from 60 to 90 percent (depending on the
shade), and eliminate 99+% of the IR.

Calobar is a trademark of the American Optical Company, however,
there are other sources of equivalent materials, again, such as our
AUR-99. In fact if you put a transmission chart of the Calobar and
the AUR-99 in the same shade, same thickness, I seriously doubt that
you could tell the difference between the two.

Almost all optical materials currently in use, plastic,
polycarbonate, and glass cut the hazardous UV light that could come
from most ordinary sources. However, if you are working with
materials and gasses that emit UV, you do need to take additional
precautions - mainly being sure that your glasses are absorbing the
proper amount of UV.

Mike Aurelius
President
Aura Lens Products, Inc.
www.auralens.com
mailto:@Mike_Aurelius


#3

So, Mike at Auralens, since you have been kind enough to jump in…

I’ve been reading the whole thread on eye protection, and some
things are clear, but others, not so much!

In your educated opinion, are special lenses called for while doing
ordinary soldering-- with feul/air, not oxy-- or are plain eyes or
eyeglasses safe? And, what do didimium glasses protect from?

Thankyou in advance for clearing this up, if you can!
–Noel


#4

Just one comment here that may be of interest re the UV – I just
had a cataract removed, and I find that the new lens that was
inserted has UV protection!

Margaret


#5

Noel -

Didymium and didymium-variant filters (like the next-generation
AUR-92) are sodium flare (yellow) filters. They will remove the
yellow in the flame, they will remove the yellow flare that results
when the flame hits metals or glass. It is not a protective filter,
but a filter that allows you to see your work better. Didymium and
the variants do not filter IR to any great extent. Please don’t
confuse them with specific design lenses for filtering IR. Kiln and
furnace workers are exposed to much greater amounts of IR than torch
workers (unless you are working 2-3" in diameter or larger).

Damage to the eye from IR sources is cumulative. And it affects
people differently. There is some data that shows that people with
high content of melanin (skin colorant) have a higher resistance to
IR damage, meaning that it will take longer for them to show the
signs of IR injury than those that have lesser amounts of melanin.
For example, people of equatorial descent (lumping together a lot of
racial backgrounds, I know) like Mediterranean, African, Indian, etc.
typically have darker skin colors, and brown eyes. These people tend
to have less IR related eye injuries than a person of northern
European descent with fair skin and blue eyes. The classic case is
the glassblowers of Murano, Italy. For hundreds of years these people
have been blowing glass in front of furnaces and glory holes with
little historical evidence of eye damage. Compare that to the
glassblowers of old England, where there was a high level of eye
damage, in fact this is where the term "glassblowers cataract"
originated (1700’s).

The eye does not have pain receptors for burns. The only indication
you have of over exposure to IR is dry itchy eyes, as the eye reacts
to the desiccation from the heat. In long term exposures, this will
lead to the development of retinal burns and corneal irritations
which lead to cataracts.

What does this mean to you? If your work is small soldering or doing
granulation, then didymium will help you see your work better. You
don’t have a massive IR exposure, but you should be aware of the
symptoms and take the necessary measures to protect yourself if your
work changes. If you are doing casting or enameling with a kiln or
furnace, or large, heat intensive work, then you need specific IR
filters.

It is a common misunderstanding that sunglasses are good to wear
while working in front of a kiln or torch, after all, sunlight is
hot, right? Sunglasses are about the worst thing you can wear, in
fact. Sunglasses typically do not filter IR. UV, yes, but UV is not
an issue for the work you are doing. Sunglasses pass IR, and with
your pupil wide open because you are working inside and the lenses
are so dark, your eye is getting blasted with IR.

I’ve read that a lot of metal workers have tried using welding
filters from the welding shop, but have found them to be too dark. A
welding supply shop is going to stock the items that welders need,
not necessarily the items that jewelers need. We have found that a
shade 2.0 filters 98% or better of the IR, while still allowing 40%
visible light. Compare this to a shade 5 (the usually available
filter) which filters 99% of IR and allows only 5% visible light.

Mike Aurelius


#6
We have found that a shade 2.0 filters 98% or better of the IR,
while still allowing 40% visible light. Compare this to a shade 5
(the usually available filter) which filters 99% of IR and allows
only 5% visible light.

Mike, I got rectangular lens plate from the local welding supplier.
It was listed as a Shade 5 and had a gold-tone metallic coating.
Looking through it, I had much greater visibility than I would have
had looking through the usual green Shade 5 lens. Is this type of
lens comparable in protection to the green Shade 5 lens? If so, it
is so much easier to work using this gold-tone lens because I don’t
have to flip it up to place solder pallions when doing platinum work.
The fellows at the welding supply shop said that the two lenses were
comparable, but I’m curious to hear your thoughts on the subject.

Thank you, Donna

p.s. I use the lens attached with longer screws over my Optivisor
lenses.


#7

Donna - I find it very difficult to believe that this "gold-tone"
filter is a true shade 5. ANSI Z87 calls out the specific
requirements for welding shade numbers (there is a CE number, but
off-hand, I’m not sure what it is), and it must meet very specific
UV, IR, AND visible light transmission percentages in order to
qualify for a marked shade number. If the “gold-tone” lens has better
visibility than a standard shade 5, it most likely IS NOT a true
shade 5 filter. The best way to find out is to contact the
manufacturer of the lens and ask for the ANSI Z87 certification for
this filter.

Manufacturers will sometimes mark lenses as being a specific shade
number without doing the tests. I’m not sure why, but they do. Other
manufacturers (like a company called Oberon) sell filters with names
that lead the purchaser to believe that they contain a specific
element when in fact it does not (Didymium II comes to mind - this
product does not contain didymium). It is very much a case of ‘Let
the buyer beware’ - be knowledgeable about what you want and what you
are going to use it for.

Mike Aurelius


#8

Hi Mike, I went back to my local welding supply shop to get safety
confirmation of the shade 5 lens I mentioned. It’s an Omniview 2 x 4
1/4 shade 5 that is green polycarbonate with a metallic gold-tone
covering that is said to exceed industry and government standards.
The green plate is not so dark as to prevent viewing work prior to
lighting one’s torch. The main drawback is that you have to protect
the metallic coating because if it is scratched off, the infrared
protection is compromised. I was told by the folks at the shop to
buy a thin protector plate to mount over the Omniview plate.

I ended up putting a thin clear polycarbonate plate over the
Omniview and mounting both onto an old optivisor head band. Being
able to see the work before and during platinum fabricating is so
much easier than when I used to use the super dark green lenses.

Donna


#9
 "green polycarbonate with a metallic gold-tone covering that is
said to exceed industry and government standards. The green plate
is not so dark as to prevent viewing work prior to lighting one's
torch." 

Donna - this concerns me quite a bit. Shade 5 is shade 5 no matter
what the manufacturer. Every shade 5 lens will transmit the exact
same amount of light based on the ANSI standards I mentioned
previously. An alarm bell rings when I hear “said to exceed industry
and government standards” - which particular standards? How does it
exceed them? As I mentioned, the standards are very specific in the
amount of visible and infrared light transmitted at very specific
wavelengths. A shade # filter has to match those requirements exactly
in order to have that exact shade number. Did they show you the
certification by the manufacturer or did they just tell you not to
worry about it (while patting you on the head in a condescending
manner)?

I have not seen a gold coated lens yet that can meet the ANSI
standards for welding applications. Gold vacuum coated lenses show a
very distinct wave pattern when tested and I seriously doubt whether
they would qualify under the shade number standards.

Mike Aurelius


#10
    Donna - this concerns me quite a bit. Shade 5 is shade 5 no
matter what the manufacturer. Every shade 5 lens will transmit the
exact same amount of light based on the ANSI standards I mentioned
previously. An alarm bell rings when I hear "said to exceed
industry and government standards" - which particular standards? 

Hi Mike, This is the literature on the lens packaging. Do you think
this is inaccurate

"Omni-View allows you to see more and do more. You see more in
clearer, natural colors. Do mre because it reflects most of the heat
and infrared generated by an arc thus keeping your eyes cooler, more
comfortable. Omni-View is made of breakage resistant polycarbonate
which is one-third the weight of glass.

Available in all conventional sizes and shades. Substituted
shade-for-shade gives protection equal to green glass. Increased
apparent brightness in shade-for-shade trade-off is non-harmful.

Care Instructions: clean with any commercial lens solution or soap
and water. Always use a clean soft cloth. Avoid scratching or
removal of gold coating.

Meets or exceeds all ANSI Z87.1 standards.

Certified model Manufactured by: Gentex Optics, Inc. Carbondale, PA
18407"

Please tell me what you think.

Thanks,
Donna


#11
green polycarbonate with a metallic gold-tone covering that is said
to exceed industry and government standards. The green plate is not
so dark as to prevent viewing work prior to lighting one's torch.

I have not seen a gold coated lens yet that can meet the ANSI
standards for welding applications.

At risk of straying outside my sphere of knowledge… This sounds
to me like a bit of cross-communication. I use shade 5 goggles for
welding (oxy-acet.), and the fact is, they are not so dark that you
can’t see your work piece, though visibility is not great. They are
not like the shade used for arc welding, where you can’t see a
thing. So, gold coating or not, if the green polycarbonate is shade
5, then that’s that, gold or no. If, on the other hand, more light
comes through these gold glasses than an established, certified
shade 5 filter, then it’s not OK, and that, also, is that. Right?


#12

Noel - correct. Shade 5 is shade 5, no matter what the material. A
standard shade 5 glass filter must have the same transmission as a
polycarb filter, or a gold-coated filter for that matter. If Donna
can see easier through the gold coated filters than she can through a
standard filter, than the gold coated filter IS NOT a shade 5.

Mike Aurelius


#13

I, for one, am very glad that we have Mike Aurelius here with us on
Orchid. I have used his glasses - Aur 92- for years when doing
glass beadmaking (lampworking). These filters protect my eyes as
well as take away the sodium flare. Since Mike has done lots and
lots of research on filters and the properties they have, it is
important that we as jewelers realize how much damage we could do to
ourselves by not using the correct product for eye protection while
doing different tasks. If I were to change from the soft glass that
I am currently using, I would also call on Mike to recommend the
correct filters for colored borosilicate (hard glass) or whatever
type of work involving high and intense light that I was going to
use. Thank you Mike for sharing your knowledge on filters and ways
to protect our eyes while working with intense light. Mike sent me
several styles of glasses to determine which was the best fit for
me, with no penalty for returning those that did not fit. A prompt
refund was cheerfully given on those that I did not keep. This, in
my estimation, is above and beyond regular service. Usual
disclaimer, happy customer etc. Beth Katz


#14

Donna - Yikes, Gentex of all companies! Yes, I believe that the
provided is inaccurate and incorrect.

Here’s what Z87.1 says are the general standards for a shade 5
welding filter:

Maximum Luminous (Visible) Transmittance: 3.16%
Nominal Luminous (Visible) Transmittance: 1.93%
Minimum Luminous (Visible) Transmittance: 1.18%
Maximum Effective Far UV Average Transmittance: 0.04%
Maximum IR Average Transmittance: 5%

This is from Table 1, ANSI Z87.1, 1989.

My guess is that they are fudging the numbers by messing with the
visible transmission. I can’t see how they can achieve a maximum
visible light of 3.16% and still call it a shade 5. And actually, the
lie is directly in the print: “Available in all conventional sizes
and shades. Substituted shade-for-shade gives protection equal to
green glass. Increased apparent brightness in shade-for-shade
trade-off is non-harmful.” Then followed by “Meets or exceeds all
ANSI Z87.1 standards.”

You cannot have an increase in visible light transmission and still
meet the standard for the shade number.

Now, having said all this, since I don’t know what the UV and IR
transmission of this lens is, I cannot say how “safe” for your eyes
it is. You can assume because of the polycarbonate base that it is a
good UV filter. You can also assume that with the Gentex name on it
that it is going to meet the IR standard. However, you know what
happens when you assume too much…

Using this filter with a kiln and/or torch may or may not be safe. I
can’t tell you that for sure without seeing a transmission chart of
the actual filter. A true shade 5 filter WILL be safe.

Just curious, was this filter more expensive than a regular welding
filter?

Mike Aurelius


#15

Hi Mike, Thanks for sharing and for responding to all my queries.

I went on the web and checked out Gentex Optics and found they are
one of the most prominent plastic lens makers in the world. They
make the Varilux polycarbonate lenses and lenses for millitary and
industry use. I also checked Google and found lots of distributors
of the Omni-View lenses and I can’t imagine all of these companies
selling a product that doesn’t meet standards, nor can I imagine a
company of Gentex Optics not protecting it’s integrity to the highest
standards.

I still wanted more of an explanation but most of the distributors
just described the product similar to what I had written before. I
did, however, stumble onto a newsletter of some Solar Eclipse
Society. In it, I found an entry by Assoc. Prof. J.R.Huddle:

"Omni-View is a welder’s filter made of breakage-resistant
polycarbonate. It is very tough plastic, not easy to cut with a
hand=held coping saw - but it can be done. (It is probably better
just to use it whole, without cutting it.) The polycarbonate is
doped with material that absorbs light, and there is also a layer of
metal film on the polycarbonate. While optical quality is not as
good as solar filters you can get from Thousand Oaks or other
suppliers, Omni-View is comparable in price to the welder’s glass
with which most of us are already familiar, and it comes in the same
shade numbers as welder’s glass.

The question is: IS OMNI-VIEW SAFE for observing the sun? In 1991,
I corresponded with Gentex, and they sent me data on the transmission
of Omni-View Shade 12 and 14 as a function of wavelength. Using
these data, I followed the procedure described in B. Ralph Chou, J.
Roy. Astron. Soc. Can., Vol. 75, No. 1, 1981, pages 36-45: I folded
the transmission as a function of wavelength into the sun’s spectral
irradiance from the article by P. Moon in Air Force Cambridge
Research Laboratories, “Handbook of Geophysics and Space
Environments” (McGraw-Hill, NY, 1965) pp. 16-2 to 16-17. Numerically
integrating the resulting spectral irrandiance at the cornea, I found
that Omni-View gives the same total irradiance at the cornea as the
familiar green welder’s glass of the same shade number. The
difference is that Omni-View passes more orange and yellow light and
less green and blue light than green welder’s glass, giving a more
natural color to the sun’s image. I have used Omni-View successfully
for visual, photographic and videographic applications since 1991. I
like it; it is not as good as the metal-on-glass solar filers made
for telescopic use, but for visual use of low-magnification
photography, it is fine and its cost is similar to welder’s
glass…"

The web address of this is
http://www.mreclipse.com/SENL/SENL9906/SENL906bk.htm

Mike, would you please explain the above in layman’s terms? I
understand the different color light transmission vs green glass.
Does that mean that Shade definitions are defined by total safe
wavelengths as opposed to specific ones like green and blue?

Thanks again,
Donna


#16

Donna - Ok, I can see what they are doing, although I do not totally
agree with the way they are calculating the shade number.

As I mentioned in my previous note, one of the key factors in
determining the shade number is the maximum visible light
transmission, which for a shade 5 is 3.16%. What I believe that
Gentex is doing is modifying the typical welders filter curve (which
looks like a standard distribution curve) in such a way to transmit
light centered in the orange/yellow wave bands (560 to 600 nm) and
lowering the transmission in the rest of the visible light bands to
achieve the overall 3.16% visible light transmission. There is
nothing wrong or illegal or anything with doing this, and it does
achieve the purpose of allowing “more” light through the filter
(actually, the more “brilliant” colors), however, for metal working,
you really want to cut the yellow sodium flare at 575 nm, not enhance
it (this is what a didymium filter does). The standard welders filter
peaks at about 536 nm, so what they have done is shifted the
transmission spectrum towards the IR by about 50-60 nm.

I have nothing against Gentex, as I said they are a well-known
company with a good reputation. However, I don’t personally believe
that this particular filter is a good thing. The yellow flare that
comes from sodium burning off is distracting and annoying and all
this filter does is allow more of it to pass through.

Anyway, that is my $0.02.

Mike Aurelius