How Bright Is The Welding Arc Compared To The Sun?

The Sun is undoubtedly the brightest thing in the world, and its comparison with a welding arc seems foolish at first sight. However, some interesting facts made people ask questions like: How bright is the welding arc compared to the sun? And, Is the welding arc brighter than the sun?

Of course, the sun is brighter than the welding arc or any other thing in this world, but what made this comparison possible is the level of effect on human health by the welding arc. You can look at the sun directly with bare eyes. Although it is an unhealthy thing to do, it is a fact that you can do it without damaging your eyes instantly.

However, if you look at the welding arc without professional protective gear, you get a physical jolt through your body. High-intensity photons will instantly strike your optic nerve, making you completely blind for a few minutes. This is really a painful experience, and damage could be severe, prolonged, or even permanent. Therefore you should never try this.

In this article, I have summed up some interesting facts and figures to make this comparison simple and understandable.

How Bright Is The Welding Arc Compared To The Sun?

To measure the brightness of the welding arc in comparison to the sun, we need to consider a few scales like heat, intensity, luminosity, and radiation.

How Bright Is The Welding Arc Compared To The Sun


The temperature of the sun is 5800K which is the hottest temperature in the world. The temperature of welding arcs ranges between 3400K-3800K, which is almost to that of the sun. The temperature of the welding arc is kept that high to melt the metals and then join them. However, the sun’s temperature is almost twice that of the welding arc, and we cannot achieve this temperature on the earth. Another factor we need to consider is the radiated heat. The radiated heat of the sun is also greater than the welding arc, of course.

Intensity and Luminosity

According to a rough estimate, the intensity of a welding arc at a distance of a half meter or 20 inches is around 1000 W^m2. While at 1 meter, the intensity level remains to about half of it, but with a larger portion of shorter wavelength radiations.

On the other hand, the sun intensity level is around 1000 W^m2 at the latitude at noon in the summer months. So the intensity of earth forms 151. 48 million km is almost the same as the intensity of an arc from a distance 0f 0.5 meters. So these figures reveal that the sun is much brighter than the welding arc.

Although a small wedding arch is not as bright as the sun, it is highly intense for its small size. Now, let’s move to the second part of the problem: if the Sun is brighter than the welding arc, then why does the Welding Arc have a high level of impact on our physical health?


Sun is about 152.48 million km from the earth, and therefore, the radiated heat, and luminance that reaches the earth is a very small portion of what is actually produced by the sun. On the other hand, a welder is exposed to the radiated heat from a welding arc from a short distance. Therefore it has a more severe impact on the human body than the earth. High energy photons directly hit the optical nerves from a shorter distance causing severe pain and damage to the eyes.


We are blessed with an atmosphere that filters the solar radiation before they reach the earth-thanks to nature. The harmful ultraviolet rays are blocked in the atmosphere, and only a small portion of harmful rays reaches our hearth. In contrast, the welders are exposed to a shorter wavelength since there is no filtration medium between them and the welding arc.

UV Rays and Welding Arcs

Ultraviolet radiation has a shorter wavelength than visible rays. As we know, Welding arcs emit intense infrared, visible, and UV traditions. UV rays emitted firm the Welding Arcs can cause vision problems, blindness, cancer, and other chronic diseases to the welders. There are three types of UV rays, UVA, UVB, and UVC. Both metal arc welding and plasma welding emit all three types of UV radiation.

Most of the UV rays coming from the welding arc is UVA, but thankfully it’s not harmful to human health. UVB and UVC rays have a small portion in the spectrum, but they are extremely dangerous. 95% UVB and 100% UVC rays coming from the sun are blocked in the atmosphere, but this is not the case with witty welding arcs.

The UVB and UVC rays are absorbed in the cornea if the welder is not welding the protective gear. Also, they can damage the skin, and the prolonged exposure can cause skin cancer. Here are the major problems associated with the intensity and UV traditions of the welding arcs.

Arc Eye Or Welder Eye

Arc eye is the common name of the eye disorder conjunctivitis. UVB and UVC rays emitted by ARC welder can damage the mucous membrane of the eye. The initial symptoms of this disorder include the feeling of ‘sand in the eye’ and mild pain.

However, with the prolonged exposure to the radiations, the symptoms become more severe, including redness in the eye, or even bloodshot, poor eyesight, inability to look at the light sources, and highly sensitive eyes.


If you are a welder or do any other job in the welding workshop, you are at risk. You should wear a welder’s helmet, with a filter sheet fitted in it. Additionally, you should wear protective goggles and eye shields to protect your eyes from harmful UV radiation.

UV Rays and Welding Arcs

Skin Cancer

Welders are at increased risk of getting skin cancer, says, International Agency For Research On Cancer. The UVA and UVB rays are mutagenic and carcinogenic and can cause skin cancer, especially when the body is exposed to them, without any protective gear.


You can only reduce the risk of skin cancer in welders by following the safety data sheets and safety protocols at the workplace. Proper use of materials, controlled reactions, and use of protective gear reduce the risk of skin cancer in the welders.


The temperature of the welding arc could be as high as 3400K, which is enough to melt metal. If not handled with care, the welding arc can cause a serious burn that may cause death.


Following all the safety protocols at the workplace is the only solution to avoid burn injuries. However, human error exists, and you should seek immediate medical help in case of an accident in the workplace.


Does sunscreen stop welding burns?

Radiations emitted from the welding arc work in the same ways as solar radiations do. Therefore these rays are preventable, and sunscreen can stop welding burns caused by UV radiations.

Can you get burned from welding?

The temperature of the welding arc ranges between 3400-3800K. If a welding arc is not handled with care, welders can get burned and injured. Also, welders get sunburn from welding since welding arc produces intense ultraviolet radiation.

What type of UV light does welding produce?

Yes, welding Arc produces full-spectrum ultraviolet rays, including UVA, UVB, and UVC. Since there is no filter medium between the welding arc and welder, UVB and UVC rays can cause eye disorders, mutagenic disorders, and skin cancer in the welders.

Is the welding flash brighter than the sun?

No, wedding flash is not brighter than the sun. The temperature on the earth is around 5800K, and the temperature of the welding arc is around 3800K, almost half to the sun. Since the sun is far away from earth, the welding flash sometimes seems more intense and brighter than the sun.

Wrapping Up

Well, Sun is a real winner of the Sun Vs Welding Arc brightness competition. But answering the question, How bright is a welding arc compared to the sun, I realized that welding arc is not an underdog either.

A small welding car is bright, hot, and intense enough to have a huge impact on human health. Shorter distance and absence of any filter medium intensifies their impact on human health. Therefore it is critical to wear professional safety gear at the workplace and follow all the safety protocols.

About Dave Walker

Dave Walker, a professional welder who has been welding from an early age. Now aims to help others by making them learning skills and finding them new opportunities. He has written for many welding blogs and helped many pursue their welding goals by helping them in choosing the best welding tools of the time.

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