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Safety -- Make sure you are safe!

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  #1  
Old 2009-02-25, 9:00am
AVC-Ed AVC-Ed is offline
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Default Energy radiance information for small torches/small boro beads

This is an excerpt of a larger article published by Mike Aurelius on his blog: http://mikeaurelius.wordpress.com/20...-glassworkers/

Quote:
The following is an example using a small torch similar to a Nortel Minor, and making a borosilicate bead. The bead is two centimeters square, and in this case we will assume that because the bead is so small, that the entire bead is a consistent temperature.

If the flame is one half wide at the base and averages 6″ long, the area of the flame is 3 square inches, or 19.35 square centimeters. The distance of 16″ equals about 40 centimeters.

Plugging into the formula above, E = 4 * ( 19.35 / ( 2 * 3.14159 * 402) )

Which reduces to: E = 4 * ( 19.35 / 10053 )

Which further reduces to: E = 4 * .0019

Which results in: E = .0076

The flame alone contributes 0.0076 Watts per square centimeter at the eye.

For the working area, let’s assume that the temperature of the glass is 1800 degrees (which is a radiance of 10 Watts per square centimeter), and the area being worked is 2 centimeters by 2 centimeters (or 4 square centimeters). We’ll keep the same working distance of 40 centimeters.

E = 10 * ( 4 / 10053)

Which reduces to: E = 10 * .0004

Which results in: E = .0040

The working area contributes 0.0040 Watts per square centimeter at the eye.

Add these areas up, 0.0076 + 0.0040 and the result is 0.0117 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.

Didymium passes an average of 66.7%, so 66.7% of 0.0117 = 0.0078 (78% of TLV)

AUR-92/ACE passes an average of 59%, so 59% of 0.0117 = 0.0069 (69% of TLV)

AGW-203 passes an average of 3.4%, so 3.4% of 0.0117 = 0.0004 (0.4% of TLV)

Commentary on the above calculation for small borosilicate work:

In light of the above calculations, it would be easy for a torch worker to assume that they don’t need special eyewear to work with boro. After all, for a small bead, the standard soft glass filters seem to be blocking enough IR radiation, so that’s ok, right?

Correct, but only so far as it goes.

There are two other issues that the torch worker needs to be aware of:

First is the assumption of relative flame size. In the given example, the flame is fairly small, in the Nortel Minor range. If you are using a larger torch or using a larger flame size than what is noted above, then the above calculations would need to be redone based on YOUR torch flame size.

The second assumption is that the only thing the torch worker needs to be careful of is IR. This is untrue. High Intensity Visual radiation, as referenced here: http://mikeaurelius.wordpress.com/2007/12/25/visible-light-hazards-and-the-glassworker/ discusses visible light “flares” across the visible spectrum that are in excess 10,000 lumens (1 lumen is a candle flame). 10,000 lumens is direct sunlight on a white sand beach.

HIV is present in working soft (especially the new silvered soft glass colors) and borosilicate glass, but is more pronounced in the boro colors. Boro colors contain higher levels of metal and mineral colorants, and as these metals and minerals burn off inside the flame, they emit visible light “flares” that can easily exceed 20,000 lumens. Additionally, anyone who fumes soft or borosilicate glass can be exposed to silver/gold “flares” that can exceed 30,000 lumens.

The recommendations that I made in that article still apply, no matter the size of the piece you are making:
Proper filter eyewear is an absolute requirement for anyone working with hot glass.

Clear lenses do not provide proper filtration of UV, HEV or HIV wavelengths and should not be worn during any hot glass operation.

Didymium and ACE (Amethyst Color Enhancement) filters by themselves provide safe filtration for soft glass workers but should never be used by borosilicate glass workers without additional visible light filters. If you have light colored eyes, you may wish to consider adding additional filtration depending on your personal sensitivity to bright light.

Additional filtration may be required by anyone working with glass that contains silver additives or any other material that create bright visible light flares.

Individuals working colored borosilicate glass must always wear a shaded lens that provides a maximum of 10 to 12 percent visible light at the HEV wavelengths (which translates to a welding shade 3.0). Darker shades must be worn when working with glass that generates very bright visible light flares, such as quartz, or when working with metals such as silver or gold.

Ensure that your eyewear is providing proper filtration. Your supplier should be able to provide a transmission graph showing what your eyewear transmits at specific wavelengths.
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  #2  
Old 2009-02-25, 10:06am
NMLinda NMLinda is offline
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Default Thank you!!

Excellent!!!

Many thanks to you and Mike!! This is extremely valuable and helpful.

Kudos to you both for so graciously taking the time to do this.

Linda
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Old 2009-02-25, 10:08am
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No problem Linda. The one thing we are not going to allow happen is for "teachers" to use these numbers to justify to their students not wearing proper boro eyewear.
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Old 2009-02-25, 11:03am
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Thank you so much, Ed and Mike, for making this information available.
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Old 2009-02-25, 11:34am
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You are very welcome, Pam.
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Old 2009-02-26, 2:43am
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Thank you...
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Old 2009-02-26, 5:36am
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boro is not the only glass that has a high level of visible light... soft glass can be just as bright, depending on the ingredients... if you're going to make the claim that visible light levels are an issue, you may also want to include BOTH hard and soft glass in this new approach. Try working Raku (R-108 ) or some of the newer silver glasses. R-108 is probably the brightest glass I have ever worker... even brighter than NS- Blue Moon.
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Old 2009-02-26, 6:47am
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Quote:
Originally Posted by Mr. Smiley View Post
boro is not the only glass that has a high level of visible light... soft glass can be just as bright, depending on the ingredients... if you're going to make the claim that visible light levels are an issue, you may also want to include BOTH hard and soft glass in this new approach. Try working Raku (R-108 ) or some of the newer silver glasses. R-108 is probably the brightest glass I have ever worker... even brighter than NS- Blue Moon.
Brent, I'm not trying to be rude here, but did you even BOTHER to read my post from yesterday?

Quote:
HIV is present in working soft (especially the new silvered soft glass colors) and borosilicate glass, but is more pronounced in the boro colors. Boro colors contain higher levels of metal and mineral colorants, and as these metals and minerals burn off inside the flame, they emit visible light “flares” that can easily exceed 20,000 lumens. Additionally, anyone who fumes soft or borosilicate glass can be exposed to silver/gold “flares” that can exceed 30,000 lumens.
Quote:
Additional filtration may be required by anyone working with glass that contains silver additives or any other material that create bright visible light flares.
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Last edited by AVC-Ed; 2009-02-26 at 7:18am.
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  #9  
Old 2009-02-26, 7:22am
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No worries Ed, I'm used to rude... it's ok, I didn't take that post as rude anyway.


Yes, I read it. Before you make statements like "Boro colors contain higher levels of metal and mineral colorants", you might want to talk to the companies producing boro and soft glass color rod.


I have spoken at length to Abe at Northstar about boro formulas and soft glass formulas. When they were formulating the soft glass silver colors, they realized the silver content in the matrix had to be MUCH HIGHER to get similar results. That is why they were priced at $100 a pound and continue to be $80 a pound, even after the research and development expenses have been recouped. So your statement that boro contains more silver isn't necessarily true. I also wanted to mention that R-108 that is very common in soft glass beads is by far the brightest glass I've ever worked with.

Now we need to explore this visible light danger. More needs to be known about acceptable exposure levels and exposure durations.

Fuming for example is a very bright burst, but I don't look at it. I know where I need to hold the gold or silver in the flame and before it starts glowing brightly, I'm already looking at the piece I am fuming and not at the gold, silver or quartz rod. The same is true for the brighter glass. I know when it is going to get bright, so I don't stare at it. Any exposure I have is short and I minimize it by looking some where else.


I also have a mirror set up in front of my torch. It's a few feet away and situated so I can keep an eye on what I'm doing. The most I ever do when I'm working something particularly bright is to glance at it.

We're exposed to bright flashes all the time. Reflections from the sun are a prime example.

I'll be very interested in further information as it comes out... a new chapter... cool.
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Old 2009-02-26, 8:33am
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Then I suggest you read the article that Mike wrote as referenced elsewhere, then if you want more information, read the bibliography items in that same article.

The information is all there.
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Old 2009-02-26, 8:37am
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If you have not made contact with the manufacturers to check the accuracy of he contents of this paper, I think you should. Paul from TAG manufactures both soft and hard glass. Abe from Northstar does both as well. Henry at Glass Alchemy is a great source for boro information and I'm sure Double Helix would be able to help with information about their soft glass silver colors. I've had awesome discussions with several of these folks and they all seem to like talking about what they do. Since you're writing about the materials they manufacture for us to use, a line of communication and working relationship seems like it would be beneficial to everybody.
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Old 2009-02-26, 9:13am
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What accuracy issues, apart from that single statement, are you referring to?

Are you going to continue to nitpick at every single thing that Mike writes?

But you do bring up an interesting point, Brent, and that is communication between the manufacturers and the end users about exactly what is in their products.

To my knowledge, Glass Alchemy (major props) is the only domestic or foreign glass maker that supplies the legally mandated MSDS for their products. The only problem is you have to dig through their website to find it (it is buried on page 4 of the Resources link).

No other manufacturer, not NorthStar, not DoubleHelix, not Moretti (or whatever they call themselves these days) supply any of us with an MSDS. Legally, under OSHA regulations, all raw material suppliers are required to provide an MSDS for each raw material or product that is used in the manufacturing process. This includes bead release (ever seen an MSDS for that?).

If you are looking for a safety mission, Brent, there's a good one for you. Start working with the glass suppliers (and retail sellers!!) to provide to their customers the legally required safety information that all their customers need.
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Old 2009-02-26, 9:25am
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There's obviously going to be a limit to how much colorant will go into solution in glass, whether boro or soft, therefore how much visible flare can be produced for a rod or gather of a given size.

Brent, since you seem to know Abe at Northstar and Henry at Glass Alchemy, would you mind asking them to comment on this? If some of the German or new heavily silvered soft glasses have colorant levels that are similar to, but not more than boro, boro can perhaps be treated as the upper bound for assessing safety.

I'd also like to observe that many folks using the new heavily silvered soft glass, or german glass like R-106R-108 often use it as frit or stringer - relatively small volumes. The smaller volume of glass may also limit the total visible luminance an artist is exposed to

Linda
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  #14  
Old 2009-02-26, 10:48am
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I just got off the phone with Abe. He is definitely interested in joining us. I hope his time allows him to stop on by. Apparently he has been working on some of this stuff and he's going to check how proprietary the testing is for the company he's been working with. Hopefully we've got more input and data coming.

As far as the MSDS sheets, I'd like to see those as well. Maybe more will come out of this than anticipated. Abe seems to agree that there are quite a few companies that should be involved in this and have an interest in getting the testing done.
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Old 2009-02-26, 11:29am
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Brent - Thanks for calling Abe! It would be very interesting to hear anything he is able to tell us (without violating any proprietary agreements, of course!).

Would you mind terribly inviting Abe to comment over on the "Best Eye Health Info? How Do We Figure Out If We're Safe Enough?' thread? I think it would be very helpful to all if we can keep our growing body of information in one spot

Thanks!
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