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Safety -- Make sure you are safe!

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  #1  
Old 2006-11-02, 6:20am
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Default ACE filters for soft glass eyewear... are they all safe?

The short answer is yes... ACE filter material is the same from company to company. It's made by the same manufacturer. http://www.us.schott.com/english/index.html Check out this website... high tech stuff. I love looking at high tech uses for glass....

When purchasing glasses to protect your eyes, soft glass folks can buy from Auralens or Phillips without worrying about your eyes getting damaged by working soft glass. There is no difference in the raw ACE material used...
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Old 2006-11-02, 9:46am
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But there may be a real difference in quality of the end product.....

Have you got quality documents to support the inference there is a different in quality of finished product your controversial phrasing seems to indicate...

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Old 2006-11-02, 9:54am
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With the materials coming from the same manufacturer, the quality of the eyewear you buy is in the hands of the technician who made the lenses. It doesn't mean all end product is created equal.

It's like buying a rod of Kronos. Some lampworkers make fabulous beads and get awesome color and some don't. Same glass material manufacturer, different bead technician, so to speak.

Make sense?
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Old 2006-11-02, 10:21am
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Makes perfect sense Bonnie. There very well may be a difference in the quality of the end product... that can be discussed as well. From a purely safety aspect, there is no difference in the filtration of harmful light waves getting to the eye. I know happy customers wearing both brands mentioned. One is less money and they may not be equal on all quality levels. I hope the manufacturers can come in and talk about their products in this way. It would be benneficial to the all of us, to know more about what we are getting for our money. Lot's of products are better, some times it comes down to what you can afford to buy... some times it comes down to other factors in making the decision. A Cadillac is better built, that doesn't mean people should be afraid to drive a Toyota.
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Old 2006-11-02, 10:59am
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Are they safe, is that the question? I guess it would depend on what you consider as the definition of safe. If the lenses are not ground and polished correctly they can throw off your focus and/or your depth perception. Having worn glasses since the 3rd grade, I can attest to the difference between a correctly ground and polished lens and one which has not been. You can get eye strain producing headaches, stick your thumb in the flame, etc. You only have two eyes, please take care of them.
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Old 2006-11-02, 11:11am
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Very well said Pam. These are very valid concerns. I'd be interested to hear from anybody who has had eye strain or any bad experiences with either company. I've worn didies (not sure of brand) and boroscopes (Phillips) and have never suffered head aches or stuck my thumb in the flame due to bad focus... it is possible though and if it's a real problem and not hypothetical, let's hear about it.
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Old 2006-11-02, 8:25pm
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Hey, do you all know if this lens can be put in a salt bath to bend the frames without hurting the coating on the lens? My eye doctors office didn't want to put mine in their solution because they didn't know if it would ruin them.
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Old 2006-11-03, 3:03am
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If it's a straight up ACE lense, there isn't a coating. It's colored glass and would be fine. I have seen some with a gold coating, but I'm not sure if that is safe in a salt bath... wish I could be more help. I'm sure somebody knows for sure. I'd say it's safe, but I'm not 100%.
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  #9  
Old 2006-11-03, 6:22am
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The following is a reprint of something I wrote about seven or eight years ago, and it seems fitting to post it here:

Quote:
We are asked quite frequently to give our recommendations on what eyewear should be worn for a particular task. This is a difficult problem because of the complexity of the equation: Glass type, torch and gas combination, personal requirements, etc. The following commentary is a distillation of on-line discussions over the past year or so. Note that these are general recommendations based on general usage. Your particular situation may require more protection.

General Recommendations

The main concern for lampworkers (beadmakers) is IR radiation. NIOSH feels that normal glassworker eyewear is adequate to shield the eye from this radiation. This final conclusion from 2769 (NIOSH HETA 98-0139-2769) : Page 7, Discussions and Conclusions, 6th paragraph: "… Since the levels of optical radiation produced in these glass bead operations are generally below occupational exposure levels, many beadmakers may believe that they do not need to wear any type of eye protection. NIOSH investigators believe that appropriate eyewear needs to be worn for the following reasons:

a) To minimize sodium flare and IR levels.
b) To protect the eyes from broken glass.
c) To prevent burns of the eyelids."

While sodium flare is NOT hazardous, it is difficult to see through and filtering it out serves the wearer of such glasses well by allowing them to see their work and see the glass as it changes temperature. The key here is the word minimize. You do not have to totally eliminate IR from your workplace. Incidental IR exposure takes place all the time, and eliminating it with the technology available today would cause additional problems (example: the inability to discern the color red).

UV is not a major concern to anyone who wears glasses. This is because most optical material today do an excellent job of filtering UV to about 380 nm. UV radiation injury from any source is almost impossible for anyone who wears glasses of any kind. However, if you do not wear glasses, a pair of plano (non-prescription) safety glasses will provide all the UV protection you will need.

Sodium flare is filtered by didymium and the didymium variants. The only distinguishing factor is the additional filtration that is offered by the variants. These additional filtration lines serve to help the wearer by eliminating a higher percentage of the sodium flare, as well as distinguishing color temperatures.

IR is much more difficult to filter out because it is so pervasive in everything the hot or warm glass worker does. With so many varieties of work and IR sources, it becomes difficult to choose the best type of eyewear for a specific task. For furnace/kiln/glory hole workers, a lens that offers good visible light transmission is required for workplace safety as well as excellent IR protection.

Contrary to popular belief, a gold-coated lens does not by itself filter a sufficient quantity of IR to justify the cost or loss of visible light transmission. A white lens coated with 99.99% pure gold still transmits up to 25% IR energy from 1000 nm to 2500 nm. What is needed instead is a lens that absorbs IR. There are several varieties of lenses, beginning with the welder's series.

A shade 2.0 welders lens has an average IR transmission of 5% from 1000 nm to 2500nm, while a welders shade 2.5 has an average of just 2.5% in that same range. The shade 2.0 has an averages 25% visible light transmission with a peak of 40%, while the shade 2.5 averages 15% with a peak of 22.5%.

Another type of lens is the IR absorber. An IR absorbing glass type, like the Schott KG series, is used in the AGW™ series filters supplied by Aura Lens Products. These filters provide truly excellent IR absorption from about 800 nm to over 3,000 nm. These are the same filters used in IR laser protective eyewear.

On final way to block IR is to stack ¼" tempered plate glass with an air gap. Two or more sheets will provide approximately 80-85% IR filtration until they absorb enough energy to become IR radiators themselves.

The key point to remember in selecting proper eyewear is that you need good visible light transmission coupled with any additional IR protection that you may require. Dark lenses are hazardous to wear: you cannot see anything unless you are either outside or using floodlights in your studio. As soon as you move away from the furnace/glory hole, you cannot see. How are you going to take your glasses off when you have both hands on the punty? One additional thought - the eye is a marvelous machine: it has its own brightness filter: the pupil. When the light is too bright, the pupil closes down. When it is dark, the pupil opens up. However, when we fool the eye with dark lenses, the pupil opens wide - allowing any hazardous radiation that the dark lenses do not filter to flood into the eye. A lighter colored shade allows the pupil to help protect the more delicate and sensitive structures of your eye.

Ask to see transmission charts before you buy protective eyewear. If the eyewear supplier cannot or will not provide transmission charts, find another supplier. Remember that price does not always indicate that you are getting the best product for the money. And finally, what is good for someone in one shop is not necessarily good for you in yours.

Myth, Superstition and Urban Legend

UV Hazards - Myth
Unless your work or torch/furnace exceeds 6000 degrees F, there is NO UV hazard. Small amounts of UV are generated, but they are absorbed by any eyewear you may choose to wear. If you are working quartz , be aware that heating quartz generates vast amounts of UV, so quartz workers should wear additional UV protection or select filters that provide sufficient UV protection.

Sodium Flare - Myth/Superstition
Sodium Flare is NOT a hazard to the eye. It is an inconvenience, a distraction. It can be bright enough to hide your working area. It will not burn your retinas. It will not give you cataracts or glaucoma.

Visible Light Hazards - When it's not a myth
However, there are cases where too much light is no good either, especially when working borosilicate glass. Borosilicate glass requires higher temperatures to work (See IR Hazards) and because of these high temperatures, the color flares are much brighter. Some color flares, like Glass Alchemy Green Dwarf, require as much as a shade 8 or darker filter. Green Dwarf has a very strong potassium flare, and until we find a notch filter for it, shade 8 is the only filter available for it.

IR Hazards - definately not a myth
This is where general knowledge seems to break down. Most glassworkers, especially Hot Shop workers (traditional glassblowers, fusers, slumpers, casters) totally ignore the IR hazard, thinking that didymium lenses are sufficient protection. Look at a transmission chart for didymium, and you will see that didymium transmits over 70% IR. Hot Shop and borosilicate workers are exposed to extreme amounts of IR and must take steps to protect their eyes. IR causes long term, non-correctable cumulative injury to the eye. There are plenty of options available, from welding filters to high tech, nearly clear specialized IR filters.

Urban Legends
Many books have been written about our art/craft -- each has many hint, tips and suggestions about many facets of our work. As the case in point, Cindy Jenkins' book is about her particular torch, the HotHead. This torch is nothing more than a modification of the propane torch you can get at any hardware store. It is not capable of high temperature operation like many of the oxy-propane torches that many lampworkers use.

Problems develop when recommendations made for the HotHead torch are applied to other torches and other glass types.

If you are using a HotHead torch, you really DON'T need to wear anything but regular safety glasses. BUT, if you want to be able to see your work, and improve your art, you should wear a didymium filter to remove the sodium flare.

Do not apply this "rule" to any other torch, gas mixture, or glass type.
Working with a kiln, furnace, or glory hole requires special IR filters. Any statement to the contrary is false and hazardous to your long-term vision.
By all means, read everything you can get your hands on -- but take care when reading about safety, especially when someone makes a comment 'you don't need to worry about this'. Get recommendations from several other sources, including your own physician, or eyecare specialist.

The more you know about the hazards involved, the safer you will be.
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  #10  
Old 2006-11-03, 6:26am
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Quote:
Originally Posted by artwhim
Hey, do you all know if this lens can be put in a salt bath to bend the frames without hurting the coating on the lens? My eye doctors office didn't want to put mine in their solution because they didn't know if it would ruin them.
Kathy
Kathy - the AUR-92/ACE lenses are not coated, the filtering material is built right into the glass matrix. Unless an after-market coating has been applied by the retailer, the filters are safe to be put into a softening pot to reshape the frame.

I'm actually surprised that your optician is still using salt - most modern facilities these days are using either heated glass beads or hot air to soften the frame material.

It can be difficult sometimes to see if your filters have been coated, but most opticians are trained to look closely at the lens. Close examination will always reveal if a lens has been coated or not - it's not exactly rocket science and any optician "worth his/her salt" can tell quite easily.
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  #11  
Old 2006-11-03, 6:48am
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Brent makes a fairly broad assumption about Schott being the only supplier of ACE raw material. This is in fact, incorrect. There are at least 2 other suppliers of this identical material - it has been reverse engineered by one optical company in China and developed simultaneously by another in Japan. I'll leave Brent the job of identifying those other manufacturers if he so chooses.

As Bonnie indicates, once the raw material leaves Schott, what happens to it then is up to the individual manufacturer.

I've seen the quality of the product from Phillips. We get their product in here from time to time for lens replacement, either from not wanting to deal with the original manufacturer because of defects or because the original manufacturer refused to replace a defective product.

I cannot speak for the entire range of Phillips' manufacturing, we only see the defective materials - but what I have seen is shocking, to say the least. The optical industry as a whole bases its quality control on the American National Standards Institute (ANSI) standards for the optical industry, most of which were developed by the OLA (Optical Laboratories Association) and the OMA (Optical Manufacturers Association). Members of both associations are either on the ANSI board for the Optical Standards or were consulted.

There are two standards for optical manufacturing: Z80 for "dress" or "street" eyewear and Z87 for "safety" eyewear. The Z87 standard is based in part on Z80 but includes tougher and stricter guidelines for the safety eyewear business.

The art glass industry is somewhat peculiar in that we manufacture lenses in accordance with both standards. If a lens is being put into a safety frame, the lenses meet Z87 for impact resistance, as well as the other requirements of Z87.

Z80 calls out most of the optical quality requirements of the lenses, based on power (along with acceptable tolerances) and prism (a measurement of the difference where the optical center of the lens actually is versus where it is supposed to be).

All of the Phillips lenses that we have replaced have consistently not met the standards for Z80 in power and prism. We have seen lenses that are supposed to be zero power that have almost a 1/4 diopter (a measurement of power) of power to them. Additionally, on plano (non-prescription) lenses, the optical center of the lens is required to be aligned with the mechanical center of the lens. In almost every lens we have tested from Phillips, there was substantial prismatic power. The standards allow for a small amount of prismatic power, but the prism is to be aligned so that both lenses are in the same direction, usually base down. In pair after pair that we have examined, Phillips lenses are usually one lens base up and the other base down or out.

This mis-match in prismatic power, coupled with actual lens power will cause eyestrain, headaches, and an inability to focus properly on the work.

Additionally, in violation of the Z87 standard, which requires each manufacturer to mark their lenses with a trademark, Phillips has consistently NOT marked their lenses. Which leads a person to wonder why they would not want people to know who manufacturered the lens. In light of the above information, I believe the answer is quite obvious.

Then of course, there is the issue of mis-leading the consumer about the relative safety of their borosilicate "protective" eyewear. You can find much more information about that subject on these two links:

http://www.auralens.net/e_phillips2.cfm
http://www.auralens.net/e_phillips3.cfm
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  #12  
Old 2006-11-03, 6:53am
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An issue that comes up from time to time is IR exposure. Here's a reprint of an article I wrote in 2005 to address this issue. Note that it is primarily aimed at the borosilicate workers, but it may be of interest to soft glass workers as well.

Quote:
NIOSH and OSHA have determined that the IR TLV (threshold limit value) to the unprotected eye is 10 mW/CM2 for time periods greater than 16 minutes. (10 mW is .010 Watts)

There are two critical areas to take into account when trying to determine the exposure value of IR radiation. The first critical area is the heat source, be it a furnace, glory hole, or torch. These heat sources typically run at a higher temperature than the glass being worked, and thus are a higher hazard. The second critical area is the piece being worked. The piece will typically have two zones, the heated area, or that portion of the piece that is currently being worked, and the rest of the piece, which is radiating at a lower temperature than the worked area. All three of these areas contribute to the total radiation that the glassworker is being exposed to.

The basic forumula is: Total Exposure = A1 + A2 + A3, where Ax are the areas referred to above.

The basic formula for calculating exposure is: R * (A / (2 * 3.14.159 * r2) ) Where R = Radiance of the object in watts per square centimeter, A = the area of the radiation, in square centimeters, and r = the distance to the eye from the heat source, in centimeters.

The flame calculation is this: For a 3500 degree flame, Radiance is 75 Watts per square centimeter. If the flame is one inch wide at the base and (for example) averages 8” long, the area of the flame is 8 square inches, or 51.61 square centimeters. The distance of 16” equals about 40 centimeters.

Plugging into the formula above, E = 75 * ( 51.61 / ( 2 * 3.14159 * 402) )
Which reduces to: E = 75 * ( 51.61 / 10053 )

Which further reduces to: E = 75 * .0051

Which results in: E = .375

The flame alone contributes 0.375 Watts per square centimeter at the eye.
For the working area, let’s assume that the temperature of the glass is 2200 degrees (which is a radiance of 25 Watts per square centimeter), and the area being worked is 5 centimeters by 10 centimeters (or 50 square centimeters). We’ll keep the same working distance of 40 centimeters.

E = 25 * ( 50 / 10053)

Which reduces to: E = 25 * .0049

Which results in: E = .123

The working area contributes 0.123 Watts per square centimeter at the eye.

For the nonworking area, let’s assume that the temperature of the glass is 1100 degrees (which is a radiance of 3 Watts per square centimeter), and the nonworking area equal to the working area, or 50 square centimeters). Remember that if you are building a large piece, the nonworking section will continue to grow, so keep that in mind. We will also keep the same working distance of 40 centimeters.

E = 3 * (50 / 10053)

Which reduces to: E = 3 * .0049

Which results in: E = .015

The nonworking area contributes 0.015 Watts per square centimeter to the eye.

Add these areas up, 0.375 + 0.123 + 0.015 and the result is 0.513 Watts per square centimeter to the unprotected eye.

Now, let’s figure the protection value of the various filters. Remember that the IR TLV is 0.010 Watts per square cm.

Phillips Boroscopes Shade 3 passes an average of 55%, so 55% of 0.513 = 0.282

Phillips Boroscopes Shade 5 passes an average of 40%, so 40% of 0.513 = 0.205

Aura Lens AGW 203 passes an average of 3.4%, so 3.4% of .513 = 0.017

Aura Lens AGW 286 Shade 5 passes an average of 1.5%, so 1.5% of .513 = 0.008
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Old 2006-11-04, 12:10am
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Quote:
Originally Posted by MikeAurelius
Kathy - the AUR-92/ACE lenses are not coated, the filtering material is built right into the glass matrix. Unless an after-market coating has been applied by the retailer, the filters are safe to be put into a softening pot to reshape the frame.

I'm actually surprised that your optician is still using salt - most modern facilities these days are using either heated glass beads or hot air to soften the frame material.

It can be difficult sometimes to see if your filters have been coated, but most opticians are trained to look closely at the lens. Close examination will always reveal if a lens has been coated or not - it's not exactly rocket science and any optician "worth his/her salt" can tell quite easily.
Thank you for the info Mike! We live in the boonies, maybe that accounts for the salt bath still in use. Around here, "If it ain't broke, don't fix it." applies to most things. I'm guessing the lady just didn't want to deal with them. I got the grumpy one the day I was in. Would be nice to have the glasses fit my face better. Maybe I should stop by on a day when the nicer one is there!

Kathy
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Old 2006-11-04, 11:19am
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Anybody interested in preserving this information should print our pertinent data....

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Old 2006-11-05, 7:04am
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Old 2006-11-06, 6:12am
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Quote:
Originally Posted by MikeAurelius
Brent makes a fairly broad assumption about Schott being the only supplier of ACE raw material. This is in fact, incorrect. There are at least 2 other suppliers of this identical material - it has been reverse engineered by one optical company in China and developed simultaneously by another in Japan. I'll leave Brent the job of identifying those other manufacturers if he so chooses.
Are you using one of these reverse engineered materials? I know Phillips was going directly to Schott... are you guys buying directly from Schott? If not, why not?
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Old 2006-11-06, 7:15am
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Mine is only user-data, but here goes. I've been wearing corrective lenses since I was 10. As Pam says, properly ground lenses are vital. I've had some bad glasses over the years and it was always easy to tell within days that there was a problem.

I've been an exclusive ACE wearer since I started making beads 9 years ago, with the exception of my first year with only didy's. I've gone through 3 pairs of ACE glasses and never had a problem with the lens quality at all. You might wonder why 3 pairs? I bought the cheapie frames the first time, then upgraded, then knocked my 2nd pair off a 2nd floor balcony railing (don't ask). They didn't break, but they were scraped and scratched beyond usability. That's only 3 sets of lenses, maybe I've just been lucky, but they've all been well made. I bought my first pair from Arrow Springs, and my 2nd & 3rd from Generations Glass (Kristian rocks!)
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Old 2006-11-06, 8:52am
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Karen... are they Auras or Phillips that you got from Generations? I believe they carry both brands now, but used to only carry Phillips... and yes... Kristian does ROCK!
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  #19  
Old 2006-11-06, 12:11pm
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All ACE/Phillips, not Auras.
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  #20  
Old 2006-11-09, 3:41am
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Quote:
NIOSH and OSHA have determined that the IR TLV (threshold limit value) to the unprotected eye is 10 mW/CM2 for time periods greater than 16 minutes. (10 mW is .010 Watts)

There are two critical areas to take into account when trying to determine the exposure value of IR radiation. The first critical area is the heat source, be it a furnace, glory hole, or torch. These heat sources typically run at a higher temperature than the glass being worked, and thus are a higher hazard. The second critical area is the piece being worked. The piece will typically have two zones, the heated area, or that portion of the piece that is currently being worked, and the rest of the piece, which is radiating at a lower temperature than the worked area. All three of these areas contribute to the total radiation that the glassworker is being exposed to.

The basic forumula is: Total Exposure = A1 + A2 + A3, where Ax are the areas referred to above.

The basic formula for calculating exposure is: R * (A / (2 * 3.14.159 * r2) ) Where R = Radiance of the object in watts per square centimeter, A = the area of the radiation, in square centimeters, and r = the distance to the eye from the heat source, in centimeters.

The flame calculation is this: For a 3500 degree flame, Radiance is 75 Watts per square centimeter. If the flame is one inch wide at the base and (for example) averages 8” long, the area of the flame is 8 square inches, or 51.61 square centimeters. The distance of 16” equals about 40 centimeters.

Plugging into the formula above, E = 75 * ( 51.61 / ( 2 * 3.14159 * 402) )
Which reduces to: E = 75 * ( 51.61 / 10053 )

Which further reduces to: E = 75 * .0051

Which results in: E = .375

The flame alone contributes 0.375 Watts per square centimeter at the eye.
For the working area, let’s assume that the temperature of the glass is 2200 degrees (which is a radiance of 25 Watts per square centimeter), and the area being worked is 5 centimeters by 10 centimeters (or 50 square centimeters). We’ll keep the same working distance of 40 centimeters.

E = 25 * ( 50 / 10053)

Which reduces to: E = 25 * .0049

Which results in: E = .123

The working area contributes 0.123 Watts per square centimeter at the eye.

For the nonworking area, let’s assume that the temperature of the glass is 1100 degrees (which is a radiance of 3 Watts per square centimeter), and the nonworking area equal to the working area, or 50 square centimeters). Remember that if you are building a large piece, the nonworking section will continue to grow, so keep that in mind. We will also keep the same working distance of 40 centimeters.

E = 3 * (50 / 10053)

Which reduces to: E = 3 * .0049

Which results in: E = .015

The nonworking area contributes 0.015 Watts per square centimeter to the eye.

Add these areas up, 0.375 + 0.123 + 0.015 and the result is 0.513 Watts per square centimeter to the unprotected eye.

Now, let’s figure the protection value of the various filters. Remember that the IR TLV is 0.010 Watts per square cm.

Phillips Boroscopes Shade 3 passes an average of 55%, so 55% of 0.513 = 0.282

Phillips Boroscopes Shade 5 passes an average of 40%, so 40% of 0.513 = 0.205

Aura Lens AGW 203 passes an average of 3.4%, so 3.4% of .513 = 0.017

Aura Lens AGW 286 Shade 5 passes an average of 1.5%, so 1.5% of .513 = 0.008
OK, let's play with some numbers. I know this makes some peoples head hurt. I know you look at this data and part of you says "OK, I'm not doing the math, I'll just believe it.". That's ok and a normal response to math, but I love math anhd I love making sense of it, so let me do the work for you.

Since this information about IR exposure and how to calculate what's safe for borosilicate workers has been brought into play in an ACE thread, let's put in some bead making numbers. I'm only going to deal with the flame, not the glass temps... I don't need those numbers to make my point, just one part of this scary equation...

If we look at a flame less than half the size in the equation provided (a more typical bead making flame), the flame alone contributes 0.1865 watts per square centimeter at the eye, according to this equation. An ACE filter would pass .1305 watts which is 13 times the acceptable limits of 0.010. According to your website Mike, the ACE lense will pass 70-80% of the IR present, I used the 70% value, just to give you a better outcome, since you make quality glasses. How is it safe to work soft glass with ACE lenses if this equation is true? If we go by the numbers provided, almost everyone needs more IR protection than ACE lenses provide to just look at a lampworking flame.
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  #21  
Old 2006-11-09, 6:26am
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Brent, you made a classic error in your assumption. If you are going to assume the flame for a soft glass bead is half that shown in the calculation, you have to actually use the true number:

.5" x 4" = 2 square inches or 12.90 square centimeters. THEN plug that into the remaining formula:

75 x (12.90/10053)

which reduces to

75 x 0.00128

which equals .0962 times 70% = 0.067

Yes, this is 6.7 times the TLV, but the other part of the TLV is that it is time related. The TLV is set for exposures exceeding 16 minutes (I believe). How long does it take to make the average bead? 5 minutes? 10 minutes? Longer?

But you are correct, there is significant exposure to IR any time a torch is turned on.
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  #22  
Old 2006-11-09, 6:57am
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I figured it by using a little lager flame. I know folks who spend way longer on a bead (I do). I still don't think we are in any danger. I think there is something wrong with the calculation. If the calculation holds water, then all of the companies producing ACE lenses are wrong about how safe it is. I'd really like to get to the bottom of this. Thanks for hanging in there with me.
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  #23  
Old 2006-11-09, 7:08am
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No problem, as long as it stays on the high road.

For the sake of discussion purposes, how about if we continue this discussion on TAM, there seems to be more "meat" over there.

Then, once we've reached a consensus, I'd be happy to post the results over here.
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  #24  
Old 2006-11-09, 7:11am
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Quote:
Originally Posted by MikeAurelius
Brent, you made a classic error in your assumption. If you are going to assume the flame for a soft glass bead is half that shown in the calculation, you have to actually use the true number:

.5" x 4" = 2 square inches or 12.90 square centimeters. THEN plug that into the remaining formula:

75 x (12.90/10053)

which reduces to

75 x 0.00128

which equals .0962 times 70% = 0.067

Yes, this is 6.7 times the TLV, but the other part of the TLV is that it is time related. The TLV is set for exposures exceeding 16 minutes (I believe). How long does it take to make the average bead? 5 minutes? 10 minutes? Longer?

But you are correct, there is significant exposure to IR any time a torch is turned on.
Mike, if you subtract half of each side on the flame measurements, you get 1/4 the size... not half. I shaved a little off of each side and got close to half the surface area. I didn't make a classic mistake.
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  #25  
Old 2006-11-09, 7:13am
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Quote:
Originally Posted by MikeAurelius
No problem, as long as it stays on the high road.

For the sake of discussion purposes, how about if we continue this discussion on TAM, there seems to be more "meat" over there.

Then, once we've reached a consensus, I'd be happy to post the results over here.
I think we can continue here as well. There's more folks here and some don't like TAM. We can post the high points as we move along. Thanks for revisiting this discussion. I hope we can stay professional about it. These are things I think the lampwork industry needs to know for sure.
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  #26  
Old 2006-11-09, 9:15am
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Back on track with the ACE lenses. I talked to Phillips today. It's the first time I've ever contacted the company. I thought it was time to get the other side. I was assured that their grinding and polishing procedures are top notch. Is this true? I have no idea. So, what can we do to test this? I can borrow some stock from my supplier and have a reading done on the lenses. I don't want to get them directly from Phillips. I am also willing to borrow some Auras and have them tested by the same person on the same machine, so there isn't a calibration issue. The less variables, the better the results will be. Let's see once and for all who's better. Is there a noticeable difference in quality, we'll see. Hopefully, this will put the ACE lense subject to rest.

I'm also working on getting the IR readings measured in a real life situation. Hopefully that will put that issue to rest as well.

Knowing what we are dealing with on safety issues is a good thing. This industry is relatively new. Using the welding industries standards doesn't always apply. I'm willing to put in some effort to gather data for our community.

I'll let you all know the results.
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  #27  
Old 2006-11-09, 11:38am
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All I can say is be sure you get some kind of statistical sampling. And you are correct, you should NOT get samples from either one of us.
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  #28  
Old 2006-11-09, 11:41am
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On the IR issue as posted above:

Brent and I are discussing certain aspects of the calculations on TAM. He's made a couple of very good points that I'm taking into consideration.

At this point in time, my position is that Brent is probably correct to a point. The 67% basis for heat from the flame is most likely wrong, but how wrong, I don't know yet.

I've got a call placed to the physics department of the local university and I'll be discussing mass calculations of radiant heat on solids versus plasma (flame). Once I have a better handle on things, I'll be able to present a much more coherent response to this issue.

For now, I'd like to have folks temporarily ignore the issue of IR transmission as it relates to soft glass.
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  #29  
Old 2006-11-09, 1:18pm
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Thank you,

Let us know what you find out Mike.

I'm working on getting the IR levels tested. I'll let you know how that progresses.
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  #30  
Old 2006-11-09, 2:05pm
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This discussion has become very technical, but I wanted to chime in on the lens quality side.

I also wear prescription lenses, and have had both good and bad lenses. I don't prescription safety glasses because I wear contacts.

I bought a pair of $35 Auralens glasses first, and found that the lenses were very poor. Maybe it's because I bought the cheap pair, but that really shouldn't make a difference. They were quite a strain to wear.

In August I bought a $120 pair of ACE glasses, and I've been very happy with them. Maybe the difference is that I bought better glasses this time. I think the price should be affected by the quality of the frames, and *not* the quality of the lenses. If you're selling safety glasses, all your lenses should be top-notch. But maybe that's not how it is.

Mike mentioned that he had customers who came to him for replacement lenses because they didn't like the customer service they received from Phillips. I think it's only fair for me to say that I switched to ACE because of the service I got from Auralens when I tried to order glasses direct from them. (I ended up buying the $35 pair from Glasscraft, and only because I had already waited a month and didn't want to wait any longer.)
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