Welding requires various forms of protection for the welder. Welding produces forms of light that are potentially damaging to welder’s eyes. Hoods with the proper lens are essential. It is important to know and understand what the numbers associated with the shading of welding lenses mean and how to choose the proper shade of glass.
What do welding shade numbers mean? The numbers associated with welding shades indicate how dark the glass is in the lens. The higher the number, the darker the glass.
The shade of glass that you choose for your welding helmet is dependent on many things. The one thing that surprises most people is that the shade number of the lens doesn’t have anything to do with eye protection. This article is a guide to help you determine what job needs what number shade.
Different Jobs Different Numbers
There are many jobs in the shop requiring eye protection. Any job that produces a high level of UV intense light calls for wearing a welding hood or goggles to protect your eyes from the UV exposure. Most of these jobs involve processes that necessitate high heat. In general, the shade number categories associated with welding lenses denote the type of welding or cutting for which the number is appropriate.
- Welding – 8 through 13
- Cutting – 5 through 8
- Grinding – 3
Welding and Cutting
Electric arc welding in its many forms and methods is probably the best-known function in the shop that requires special protection from the light produced when the welding begins. There are several dangers from the light that is produced by a welding arc.
- Ultraviolet light – UV light radiation breaks into three classifications or categories. The wavelength of the light denotes these categories.
- UV-A – The longest wavelength of UV light passes through the cornea and is absorbed by the lens of your eye
- UV-B – UV light with wavelengths that falls in the middle of the UV light range. The cornea absorbs most of this wavelength of UV light
- UV-C – IV-C is the shortest of the UV wavelengths and is also absorbed by the cornea
If you have ever suffered from an “Arc eye,” you understand the discomfort this condition can cause. Arc eye is an inflammation of the mucous membranes of the eye and can be a serious issue.
Before you continue reading, here is an article we wrote about eye arc and the symptoms.
Cutting is not so much a problem with UV exposure as it is the infrared radiation that can harm your eyes. Infrared radiation transfers heat to the lens of the eye, which can cause cataracts over the long term.
The visible spectrum of light causes the least damage to the eye. Exposure to an intensely bright welding arch with no lens protection can quickly overwhelm the eye’s ability to react to prevent the light from reaching the retina. The bright light from an arc or a cutting torch can result in temporary blindness and rapid eye fatigue.
How dark should a welding helmet be?
How dark should a welding helmet be? well, OSHA, the Occupational Safety and Health Administration, has a set of guidelines for choosing the shade of welding lens that is appropriate for different types of welding activities. The shade numbers vary from 3 to 14 which the darker. In short, these break down as:
|Type of Welding||Shade Numbers|
|Shielded Metal Arc Welding (SMAW)||7 – 14|
|Gas Welding||4 – 8|
|Oxygen Cutting||3 – 6|
|Gas Metal Welding||7 14|
|Plasma Arc Cutting||8 – 14|
|Torch Brazing||3 – 4|
|Carbon Arc Welding||14|
For a more in-depth look at the OSHA recommendations for shade number selection for specific forms of welding, visit the OSHA website at this link.
What Shade is Safe for Welding?
What shade is safe for welding? Many experts or professionals recommend a shade number between 9 to 13 as a good and safe number. With the increase of Amperage, you should also have to increase the shade of the welding lens, the higher the number the darker the shade will be.
However, there is a lot of confusion about what shade numbers mean in relation to safety and the protection the lens affords for your eyes. What is not understood by many people, even professional welders who have been in the trade for years, is that the shade numbers bear no relationship to the protection from UV and other radiation to your eyes.
In the United States, almost all quality welding lenses include a UV light filter that blocks 100 percent of the UV light radiation. What this means for you is that the shade number is more about your comfort than it is about protection from harmful UV radiation.
With the understanding that your eyes have protection from the damaging UV radiation, the shade numbers should be a guide for the user to select the most comfortable amount of darkness without sacrificing visibility of the workpiece.
Passive or Active?
Welding lenses come in two types, passive or active. Passive lenses have been around since people started welding. It didn’t take long before the welding hoods and goggles with which we are familiar today became standard issue for welders. These hoods allowed the welder to replace the lenses as needed for darker or lighter shades.
Replacing lenses was a time-consuming effort, and, all too often, a dropped lens would mean lost time and expense. Many times, rather than spend the time and effort to change a lens, welders would work with a lens shade inappropriate for the job and would receive eye damage. Technology found an answer.
New welding helmets often come fitted with an auto-darkening lens that are almost clear when they are inactivated. When the welder strikes an arc, the lens senses the flash and instantly darkens to the pre-set shade number. It is now possible to weld and scrutinize your work without having to remove and re-adjust your welding hood.
Each type of lens has its advantages and disadvantages. Both passive and active lenses have a place in the modern welding shop.
Related reading: Are Auto-Darkening Welding Helmets Safe? What You Need To Know
Passive Lens Disadvantages
- May cause neck pain or even injury because of the repetitive nature of the movements required to use a hood fitted with a passive lens.
- Using a hood with a passive lens requires more room to operate
- Using a passive lens in a hood requires a higher level of skill to manage the welder and the hood at the same time
- Performing tack welding with a hood fitted with a passive lens is all but impossible because of the need to check each weld before making the next weld.
- Requires keeping a variety of lenses on hand for different types of welding or cutting
Passive Lens Advantages
- Lenses are cheaper than the auto-darkening variety
- Passive lenses are not subject to battery failures because of electronic issues
- No batteries are required for a passive lens to operate
Auto-darkening Lens Disadvantages
- Requires batteries
- More expensive
- Can be a bit heavier than a passive lens because of the necessary sensors, electronics, and batteries
- If the electronics fail, the lens becomes useless
Auto-darkening Lens Advantages
- Variable shade options allow you to set the shade you need for the job at hand.
- No neck strain from continually flipping the helmet down when welding
- Sensitivity adjustments and delay adjustments allow you to customize the way your lens reacts to the work
- Some lens and helmet configurations have memories so that you can store pre-sets on your helmet for different welding jobs
- Less unproductive time spent changing lenses and raising and lowering your hood to check your work.
- More comfort and less fatigue for the user
Production welders, by and large, opt for auto-darkening helmets that give them the greatest flexibility. The average home or hobby welder, who performs a limited number of welding jobs with one type of welding machine, may find that a less expensive welding hood fitted with a quality welding lens with a shade number of 10 serves very well.
How do I choose an auto darkening welding helmet?
Have you ever wondered how to choose the perfect auto darkening welding helmet?, here we wrote an article talking just about that topic, you can check all details: How To Choose A Welding Helmet: What To Consider
Don’t be in the Dark
Whichever you choose, passive or active, don’t be in the dark about how to choose the lens shade that is best for your work. It isn’t a matter of protection. It is a matter of comfort and the quality of work that you can perform. Being able to see adequately and remain comfortable with the brightness of the light that lens is passing is the key to finding that right shade of welding lens. So, strike an arc, but don’t be in the dark.