[TheForge] Re: Cheap Autodarkening Welding Helmet.

[Steve Smith]

Kenneth Mayer wrote:

>>Date: Sat, 09 Aug 2003 19:11:10 -0500
>>From: xlch58@swbell.net
>>
>>I had heard that before.  What I am curious about is how can you tell
>>that it is in fact blocking the UV?   I generally don't trust cheap
>>tools from Harbor Freight(or elswhere)  and generally inspect and test
>>them to the debree that I can on the odd occassion that I buy any these
>>days.  So how does one test the UV permeability of a lens?  I can tell
> 
> 
> 
> If the front (clear) shield is polycarbonate, it absorbs 99%+ of the UV.
> There's an OSHA spec that requires welding lenses to provide UV protection
> at all times.  The instruction sheet that came with the helmet probably had
> a paragraph that said to use only manufacturer-provided front shields, so as
> to maintain the UV protection.
> 
> A quick go/no-go test for UV absorption is to look at a UV light source
> through the lens/shield.  The light source souuld should appear dark.

I agree that the front clear plastic shield should stop the UV.
You can't tell anything, however, about UV by looking--UV is not visible 
to the human eye.

Steve Smith