[TheForge] Vision damage and welding shields pt 2

Mon Jan 13 22:09:01 2003

Note that Speedglas has been getting more reasonable in price. You can 
get the variable shade mask a fair number of places on line for less 
than $250, for example:
http://www.weldingsupply.com/cgi-bin/einstein.pl?Next::43:UNDEF:OR:R::PR
http://www.cyberweld.com/horspeed.html
The second has the Speedglas Utility helmet for $125.

I know nothing of the above vendors.

Steve Smith

[email protected] wrote:
> The ANSI Z87.1-1989 standard referenced in the add, and to which OSHA 
> applies to all eye protection devices, seems to require BOTH UV and IR 
> protection to be in effect whether the device is energized or not.     I 
> did a google search on auto darkening helmets and eye damage and came up 
> with several articles that  indicate the same, including one on the 
> Lincoln Electric site.    The real question I have for the Harbor 
> Freight helmets is : Do they actually perform to the  spec?  It is real 
> easy to print "ANSI Z87 compliant", in the add, quite another to 
> actually build it in the product.   The add actually states only "UV/IR 
> protection" and "Meets ANSI Z87.1-1989 standards"  both of these 
> statements are far from conclusive.   Harbor Freight items are not know 
> for their rigorous quality assurance process.   That being said, I have 
> an older autodarkening cartridge from northern that I use, but need to 
> replace now, since it has a major crack in the lense.  Still works, but 
> I think some arc light is making it through now.   I will probably look 
> at the referenced Harbor Freight unit.    I will probably blink when I 
> strike the arc, but if you have a high end speedglass or somesuch hood, 
> don't feel the need to blink.
> 
> Charles
> 
> 
>> "Bruce Freeman" wrote:
>>  
>>
>> Is flash BURN really an issue here?  "Burn" implies actual damage due 
>> to UV
>> on the eye.  (SOME of this damage does heal, but you may be right 
>> about it
>> being cumulative.  I simply don't know.)  What I WOULD expect is flash
>> "dazzle", where the bright visible (non-UV) light dazzles you, causing 
>> your
>> pupils to shrink, leaving an intense after-image, and generally making it
>> difficult to see � but without doing permanent damage to your eyes.
>>
>> I have virtually no experience with these helmets, not being a welder
>> myself. (I've worn one once or twice.)   But what I DO know is that 
>> ordinary
>> window glass is virtually opaque to UV.  I don't know the "% 
>> transmittance"
>> of glass to UV light, only that it's quite low.
>>
>> (FYI, "% transmittance" is the percentage of the incident light that will
>> pass through a layer of glass of some standard thickness, usually 1 
>> cm.   If
>> 99% of the UV light is absorbed by a 1-cm glass plate, then 99.99% 
>> will be
>> absorbed by a 2-cm layer, but only about 40% will be absorbed by a 2-mm
>> glass plate.  Transmission it's highly dependent upon wavelength.  A 
>> glass
>> that's clear for white light can be "black" for UV light.)
>>
>> Bottom line is that if your color-changing mask does pass too much UV 
>> light
>> in that brief interval before it darkens, then the fix would be to add an
>> additional filter of clear glass of sufficient thickness to filter out 
>> all
>> the UV, regardless of the color of the changeable filter.
>>
>>  
>>
> 
> 
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