Just about any welding, cutting, or brazing process produces measurable and damaging amounts of light. It occurs in the infrared, visible, and ultraviolet light spectrum, but the most damaging is the ultraviolet portion. This is due to the fact that the ultraviolet light spectrum has a shorter wavelength, and shorter wavelengths have more energy. For example, imagine when your welding lead gets caught on something and you snap it to make a wave go through it to free it up. Now try to make more than one wave go through your lead. It takes much more energy doesn’t it? The same principle holds true with welding power. Higher energy welding produces higher levels of ultraviolet light, and in turn more danger to your eyes.

To be safe, you should never look directly at an arc without eye protection if you’re closer than 50 feet. Anything within a 50 foot radius requires eye protection. The amount of protection you’ll need will depend on how close you are to the arc.

Arguably the most important piece of equipment used in welding is the welding hood. The welding arc is capable of causing severe eye damage. Welding ‘flash’ is an often mentioned injury among those in the welding trades. To protect against this you’ll need to wear a proper hood with the correct filter lens.

Here are some of the recommended lens shades for different welding, cutting, and brazing operations.

Welding Operation–Shade Number

Shielded metal-arc welding
1/16-, 3/32-, 1/8-, 5/32-inch electrodes–10

Gas-shielded arc welding (nonferrous)
1/16-, 3/32-, 1/8-, 5/32-inch electrodes–11

Gas-shielded arc welding (ferrous)
1/16-, 3/32-, 1/8-, 5/32-inch electrodes–12

Shielded metal-arc welding
3/16-, 7/32-, 1/4-inch electrodes–12

Shielded metal-arc welding
5/16-, 3/8-inch 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 to 6 inches–4 or 5

Heavy cutting, more than 6 inches–5 or 6

Gas welding (light), up to 1/8-inch–4 or 5

Gas welding (medium), 1/8- to 1/2-inch–5 or 6

Gas welding (heavy), more than 1/2-inch–6 or 8

Source: 29 CFR 1926.102(b)(1).

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