Forge UV rays fact or......

Fiction.

I got this of another board. SSso what you think. This has nothing to do with the infrared just the UV.

Bruce -- Thu Feb 28 10:54:17 PST 2002
UV radiation

There seems to be a misunderstanding among blacksmiths about UV radiation from forge fires, etc. There is none. UV radiation is a concern when using an electric arc, and may be a concern using acetylene. But a forge never gets hot enough to emit significant amounts of UV radiation.

I've known this for years, but decided to find out theoretically. Not knowing the governing (black body emmission) equations off hand, I searched the web and found a spreadsheet which shows a plot of frequeny versus intensity, based upon temparture and radiating area. I wanted to make a comparison between normal solar UV exposure and UV from a forge. Rather than deal with the questions of radiating area (what's the radiating area of the sun?), loss due to distance (squared), and loss by absorption by the atmosphere, I simply compared the radiation from two sources of equal area, one at the temperature of the surface of the sun (5700K = 9800F) and one at 3000F, which is hotter than any forge you're likely to find. I plotted the two curves on a logarithmic scale.

The results were interesting. In the UV-A region, the "solar" intensity is over one hundred thousand (100,000) to nearly ten million (10,000,000) times that of the "forge". In the UV-B region it ranges from nearly ten million to nearly one hundred million (100,000,000) times. In the UV-C region it ranges from nearly one hundred million to one hundred billion (100,000,000,000) times.

Although this isn't strictly a quantitative comparison, due to the assumptions stated previously, it clearly shows that there's no appreciable risk from UV radiation from a forge.

So don't worry about wearing fancy UV-protection when working at a forge. Wear your safety glasses to protect you from flying objects, scale, flux, etc.


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My eyes don't hurt as bad after using UV glasses.
Without them, my eyes get sore.(and very very dry)
I have used other glasses, but the UV's are my favorite.

Unfortunately the author doesn't even state what kind of forge we're talking about. Presumably coal; I have come across information that suggests coal doesn't give off as much radiation in general due to the coal itself acting as an insulator.

Another issue would be what kind of work you are doing- most damascus work necessitates looking into the heat source to determine proper temperature. Traditional blacksmithing doesn't entail nearly as much peering into the heat source.

A third issue would be how long and how often you are doing said work. If you are working full-time every day it is wise to take every precaution you can against all cumulative dangers.

A gas forge with a refractory lining -does- throw off measurable amounts of UV and especially IR. I also look right into mine when doing damascus work- making it much more comperable to working in a glassblower's glory hole or kiln enamelling. I'm going to stick to my didymiums for now and keep researching the subject for better options.

I'm also not convinced of the assumption made based on the comparison of the Sun to the author's computations of a hypothetical forge. Sure, a forge gives off appreciably less radiation than the Sun... but if you look right at the Sun for any short duration you'll be permanently blinded. The lesser amount given off by the forge hasn't been shown to cause -no- damage, especially in the cumulative sense.

There is also no mention of IR given the advice to do away with '...fancy,' eye protection. IR is more of a concern than UV and is mostly why I wear eye protection when working.

I'd rather err on the side of caution when it comes to my eyes... but I guess it is up to each of us to decide that for ourselves.

Depends on how you define "significant amounts". If you look up the information, it's sometimes surprising how low a level can be harmful. You also have to take into account, skin vs retina/corneal damage. Different wavelengths are absorbed in different areas of the eye. Mid-UV(180-315nm) and far-IR (1400nm-1mm) damages the cornea surface and Near UV (315-390) damages the lens, while near-IR (400-1400) damages the retinal area. The first group is what you are feeling when your eyes feel irritated and dry after using an arc-welder without proper eyewear or looking at a white/yellow hot piece of steel for a couple hours while forge welding. You basically "sunburned" the surface of your eye. IR and visible light damage will be noticed as blind spots due to destruction of receptor surfaces on the retinal wall. Can a forge cause irreversible severe damage?...probably not, but if it's easy to avoid, I'd go ahead and avoid it so I don't have to care if it can or can't.

Check this out under goggles

www.ehs.berkeley.edu/pubs/factsheets/25eyeprot.html

I think welding goggles might work, althought the argument I have heard against them is that a gas forge throws out much more IR than oxy/acetylene welding and you experience it for a longer duration. Also since the lenses are dark your pupils simply open up more and let more IR in.

Don't know how true it is, but see Hrisoulas, 'The Pattern Welded Blade,' p. 8 for his experience.

My main reason I'm looking at alternatives to welder's shades is that I can't see what I'm doing, which is a danger in itself...

I am currently leaning toward a bifocal product from www.auralens.com , but am waiting for a call-back on the specifics for the materials. These glasses have something more like a welder's lense in combination with something close to didymium. They'll make them to order and I was anticipating having the dark shades on top so I could look into the forge and then peer through the bottom material when forging...

A glassblower friend of mine loves his.. ( which are diff than the ones I'd order...) We'll see...

NOTE: Fixed link 3/5/02

I got this reply from a glass blowing place today.


--------------Snip-------------------------

Dear Bob,

The glasses that most scientific and artistic glassblowers use are
Didymium. They can be purchased for a few different company's. Sometimes
your local eye care center can order them for you as well. Here are a few
company that I know has them available.

Mancini Optical 1-800-887-3937

Wale Apparatus 1-800-334-wale

---------------Snip----------------------

I also asked them about the type of heat source (forge) they are using and the person answering my e-mail forwarded that part to others.

I will let you know what they say about that.

We have a ton of safety catalogs here at work. There are several glasses with grey tint, UV and IR protection. Look for foundry goggles also. I'll look through the catalogs and get some specifics including prices.

A lot of weldors still use the green glass, that was what it was designed for. Metal at weld temps. From all I've read I don't think didyium is the answer. I remember reading somwhere Hirsoulas has backed off his recomendation of didyium. But if you like em you like em.

Forge glasses are deep blue, supposed to have cobalt in them IIRC.
.

I still like my #2 crews green glass, just like cowboys I don't stare into the fire. I peek and peek again, i get a kinda timing out of it.

You can always go a darker shade, i think 14 is the max.
I don't think the pupil opening up is a concern if the rays are stopped. Friend of mine uses a head shield with a plastic #5 shaded shield to look in the forge and then flips it up when he pull the billet out to work.

Just staring at the heating billet is kinda mesmerizing. I lose the moment.

Welding is different than forgeing, you don't get as much IR.

Kawool is much brighter than cast refractory also.

The next forge i build will be cast refrac, I hade a little square forge of hard fire brick, it didn;t heat as fast , and the square design wasn;t so efficent but it wasn't as bright as the kawool.

refrac is tougher and last longer, it may be worth the fuel savings to get away from the kaowool.

Hey guys I just talked to our safety guy about the glasses and shields that our welders use and he stated that the glasses are to protect the welder from the flash or the flame light of the welding. The Green protects against the UV and he is going to check with the manufactures about the IR.

As we spoke I mentioned the Didydium glasses and he says he used them for years when he worked for the foundery out here. He stated that it was a safety regulation that they had to where the glasses whenever they were in the foundery. He said that he was going to contact some of his friends to see if the have any literature on the glasses and get back to me.

Just one more thing to throw into the pot.

Mike

Check this out

www.lincolnelectric.com/knowledge/articles/content/weldinglenses.asp

_______________________________________________

Quote:

But in reality, all well-constructed quality welding lenses, have a screen that filters out 100 percent of the harmful ultraviolet (UV) and infrared (IR) wavelengths and provides protection to the eyes.
________________________________________________

I may be wrong but I also think the above quote may be wrong.

www.auralens.com/images2/aur99-1.gif

Essentially welding lenses this chart indicates varying degrees of transmission- not 100% in any case. It does indicates a pretty decent rate of protection in the darker shades. I still don't feel knowledgeable about the whole '...dark shades opening up the pupil and allowing a large percentage of the (filtered) IR to enter your eye,' issue. If you filter 90% of the IR but the 10% passing through bypasses the eye's natural defense you could conceivably still be getting a damaging amount. I want to track down the source of this statement; it bothers me.

The other reason I'd like to find a good alternative to dark welding shades is so I can see what I'm doing!

I also came across this on the same site- could it explain the problem you had with gold-coated 'didymium,' lenses, Sweany?

www.auralens.com/theotherlens.html

It's really too bad there hasn't been a comprehensive industrial study that directly addresses our needs.

Anyone else come up with anything yet?

I am a diabetic. And being a diabetic I constantly get information in the mail about eye care. I have written to every place that sends me information on eye care. Every one either says they don't know what to tell me or they send me information on welding (arc & gas). I write back and explain that this is different, so they send me DIFFERENT articles on welding (arc & gas).

Somewhere there is an eye doctor that makes knives. We need to find him/her and get the real scoop.

The quote is rather vague< all well contsucted lenses.....


The chart was to show what lense for what amperage.

Light intestinity increases with amperage thus the heavy shades are for stopping the light as well as the UV and IR

There is a Dr. that hangs out in the bladeforums. He is not an optician but may be able to run something down.

Page 84 in the new Centaur catalog.

Describing a pair of clip on dark green #5. lenses........
for maximum spectacle protection against spectral emmisions found in welding and metalworking.
Meets or exceeds ANSI Z87.1 standard for UV and IR transmissions. Visible light 2%, UV 0.005%
Max. Trans., Infrared 2.5% Max. Trans.

Describing a pair of Didymium lenses..

Didymium is an element mixed into the glass lens as an effective filter of sodium flare and a sufficient filter of UV and IR rays for blacksmithing use.
Glass is an amethyst-color tinged, not dark like weldor green.

Pick your poison guys....

did you read the article about the effects of computer monitor emmisions on the eyes?