Welding lens / eclipse

[John Weaver]

We will have a partial solar eclipse here in Georgia on X-mass day. The local newspaper says to use a welding lens greater than #14 to view the eclipse. I went to the local welding shop and the guy there told me the lower the #, the greater the shading, but I think he is mistaken. Anyway, he gave me a #7 and a #11. Can I look thru both lens at the same time and have the effect of a #18 lens. Do you guys know, or can you provide a web site that may help. Thanks in advance. John.

[TWINKLE_TOES]

John,

This guy works in a welding supply house??? The higher the number the lower the luminous transmittance (lets less IR thru) A bigger danger with the small geometery welding filter would be to locate the sun by eye and then try to place the filter between you eye and the sun.
Place the filter over your eyes and then try to find the sun. The attached table will give you an idea (sorry about the indentation)

Al


TABLE EP-1--FILTER LENS SHADE NUMBERS FOR PROTECTION AGAINST RADIANT ENERGY

Shade
Welding operation number
Shielded metal-arc welding 1 1/16-, 3/32-, 1/8, 5/32-inch
diameter electrodes........................................ ................ 10
Gas-shielded arc welding (nonferrous) 1/16-, 3/32-, 1/8-,
5/32-inch diameter electrodes........................................ ...... 11
Gas-shielded arc welding (ferrous) 1/16-, 3/32-, 1/8-,
5/32-inch diameter electrodes........................................ ...... 12
Shielded metal-arc welding 3/16-, 7/32-, 1/4-inch diameter electrodes...... 12
5/16-, 3/8-inch diameter electrodes........................................ 14
Atomic hydrogen welding........................................... ......... 10-14
Carbon-arc welding........................................... .............. 14
Soldering......................................... ......................... 2
Torch brazing........................................... ................... 3 or 4
Light cutting, up to 1 inch.............................................. .. 3 or 4
Medium cutting, 1 inch to 6 inches......................................... 4 or 5
Heavy cutting, over 6 inches............................................ ... 5 or 6
Gas welding (light), up to 1/8-inch........................................ 4 or 5
Gas welding (medium), 1/8-inch to 1/2-inch................................. 5 or 6
Gas welding (heavy), over 1/2-inch......................................... 6 or

[John Weaver]

Twinkle Toes, I thought the guy here had it backwards. Can I assume that holding a #7 and a #11 together and finding the sun will give me the same as a #18 lens? John.

[TWINKLE_TOES]

John,

I don't think you should assume anything when it comes to the health of your eyes.
For example, the transmittance of shade 14 is one tenth that of shade 12. So just adding the numbers togather may not work to well. The combined effect in your case may be a transmittance close to the 11 shade.[img]/w3tcompact/icons/frown.gif[/img]

I would head for another weld shop or go for the reflection thru the pin hole trick, the later works quite well and has no danger.[img]/w3tcompact/icons/smile.gif[/img]

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