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Recently the question arose in our workshop which lens shade to use for proper eye protection. To answer that question, I looked into the guidelines and best practices to keep your eyes safe while having a clear view on the weld.
So what is the right lens shade for TIG welding? Choosing the right lens shade depends mainly on the amperage that you are welding with and the brightness perceived by your eyes. For 50 – 150 A an average shade strength of 10 is common, while 150 – 500 A is best welded with 12 or higher.
Many welders choose there lens shade based on a couple of different criteria. To be confident with your choice, I compiled a some useful information on the topic to make the selection easier for you.
Where to start choosing the right lens?
While choosing the right lens shade, safety and the well being of your eyes should be the main concern. Therefore the rule of thumb is to adjust the shade on your helmet to the highest number that allows you to still see the weld puddle. The higher the shade number, the stronger the protection (I will describe what the shade protects you off in more detail below if you are interested).
A good starting point is shade 12 for most applications, that will allow you to “shade down” if you are welding on lower amperage. If you are using a adjustable welding helmet, changing your lens shade is easy. Just set the shade strength on the knob or button and increase or decrease as necessary. This feature is included in most auto darkening welding helmets, which makes them the perfect choice for your eyes when welding many different jobs.
In case you are using a fixed shade screen, I would start with having a look at the necessary amperage you are welding 80% of the time with. The amperage allows you to generally select a shade range from the guidelines:
|< 50 A
|50 – 150 A
|150 – 500 A
Select a lens shade in the middle between the minimum and the comfort setting. If you either notice that the weld is too bright and your eyes are strained after a while, “level up” a shade. Shade lenses are consumable and quite affordable, ranging around 5$ per piece. When you notice that the selected shade is not comfortable, don’t safe here as your eyes are one of your most valuable assets as a welder.
Looking at the other end of the range, if you are barely seeing the weld puddle and feeling a headache after your shift, you probably should consider “leveling down” a shade. Exhausting your eyes finding the puddle will cause a different set of eye related problems and eats away on your concentration over a work day.
These are the two ends of the range which you can easily spot by having an eye out for the above mentioned symptoms. If you follow the above mentioned guidelines as a rule of thumb, you should be able to avoid these warning signs though.
Another indicator that you might use a lens shade that is to strong is that you have to get very close to where the action is happening. When your nose if basically touching the weld puddle, you might consider decreasing the shade strength. Good posture while welding, especially for longer duration, is important too!
The available shade lens strength
Lens shades are classified in numbers that determine the amount of brightness they filter. The available shades range from 5 to 14, with 5 being more like sunglasses and NOT SUITABLE FOR TIG WELDING! Or any other welding for that matter. No. 5 is mainly used on auto darkening helmets as a “clear view” option for protection while for example grinding. This supports your workflow by allowing you to keep your helmet on for post processing.
For welding, lens shade 8 is the recommended minimum for low amp (<50 A) welding with TIG. This is also where most adjustable welding helmets start. When 8 is a very light protection, and will let a lot of brightness through, especially when your current is higher than 50 A. Therefore it is not recommended to use 8 for long welding.
No. 14 is usually the highest available shade number. When not welding with a high current (>150 A), most likely you won’t even be able to see your weld puddle. The arc will flicker through, this setup is unlikely to be a practical solution for high quality welds.
What Radiation will the shades block and why is that important?
To understand a bit better what you are protecting against, here are some details about the emitted radiations you are protecting against while TIG welding.
First things first: Even if you are welding on a shade that is too low for the current job, you are still protected from the UV radiations. So staring at the weld pool is basically like staring at a light bulb. However similar to staring at a light bulb for to long is not recommended, constantly welding with the wrong shades will feel similarly uncomfortable.
TIG welding emits a very bright light, and therefore needs darker shades as a MIG/MAG process with equal current. Commonly the light of a TIG welding arc is referred to as more aggressive. “Sunburn” happens quicker on the unprotected skin than with most other welding technologies.
Emitted radiation from the TIG arc is UVA, UVB and UVC. UVA is also called soft UV and not absorbed by the ozone layer. So we are exposed to some UVA everyday. UVB is partially absorbed by the ozone layer in the skies and with UVA responsible for tanning the skin. UVA and UVB is not blocked to deny you a healthy skin tone but prevent the risk of unhealthy prolonged exposure. Similar to being to long in the sun. UVC, the third in the bung is completely absorbed by the ozone layer when emitted by the sun. Why is that good? UVC is very aggressive and commonly used for killing microorganisms and disinfecting in industrial application. You don’t want that constantly radiating in your eyes and skin.
The amount of radiation emitted by the TIG welding arc is determined by the current running through the torch. The higher the current, the brighter and more aggressive the light is. But not only strength, also duration is important when thinking about protecting yourself. The UV radiation emitted by a small torch will not suddenly give you a beach tan, but when your skin is continuously exposed to the UV, you will tan. And in welding, that is not a good thing.
This was a quick overview over how and why I would choose my lens shade for TIG welding. I sincerely hope this information was beneficial to you.