How Does Watch Lume Work? Different Types Of Watch Lume




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A luminescent watch is indeed fascinating. You might have seen the pictures of a lume watch online or you may even own it. This may invoke your curiosity regarding the working principle of lume watches.

To satisfy this curiosity, we will discuss everything there is to know about this topic. Let us start.

Here is a related article that might interest you on Best 10 Glow In The Dark (Luminous) Watches For Men And Women 2023.

What is Watch Lume?

What is Watch Lume

Have you ever noticed your watch glow in the dark? If so, then you may have an idea regarding what watch lume is. The luminous phosphorescent glowing solution used on watch dials is referred to as lume.

In other words, The use of photoluminescent materials makes your watch glow in the dark. This is called watch lume.

The Different Types of Watch Lume

The Luminescent materials used today in watches are not the first type of materials to be used. This is a result of many events. The watch companies have been using luminescent materials since the early 1900s.

At first, radium was used as the primary Luminescent material. Then came Prometheum. However, it was used for a brief amount of time.

Following that, Tritium was introduced as a substitute for them. After that came Luminova, a photoluminescent pigment. After a huge amount of research, superluminova was developed. In some cases, electroluminescence is also used.

How Does Radium Work?

The working principle of radium is pretty straightforward. At first, radium is turned into a powder. After that, a mixture is formed with this powder and phosphor.

Lastly, this powder is painted on the dials of the watch. Upon coming into contact with sunlight, this absorbs the UV ray. Later on, the dials glow when it’s dark.

How Do Promethium And Tritium Work?

Promethium and tritium are both radioactive materials just like radium. Both of these two elements have a longer half-life than radium. Moreover,  these are considerably less radioactive than radium. 

How Do Promethium And Tritium Work

Initially, they were applied in the watches just like radium. However,  that did not dissipate the chance of radiation completely. So, promethium was disregarded altogether.

For Tritium, however, a different method was introduced. It was turned into a gas and then enclosed in a borosilicate glass chamber along with phosphor.

This chamber was mounted on the watch dials. This gas glows in the dark, which we can identify as a watch lume.

How Does Luminova Work?

Luminova is the most commonly used material nowadays. It is a photoluminescent pigment. Most importantly, this is not radioactive. 

Luminova is made from a photoluminescent material named strontium aluminate. This material is turned into the powdered pigment we know as luminova.

Upon coming into contact with sunlight, luminova charges, and as the surroundings turn dark, the pigment glows. Superluminova is basically an upgrade over luminova for better efficiency and longevity.

How To Activate Lume On A Watch?

You do not need to do anything particular to activate lume on your watch. Simply exposing the watch to sunlight should suffice. 

As mentioned before, the lume charges in the sunlight. However, you can use artificial UV-ray as a replacement for sunlight. But, according to experts, you can get the best result only by exposing the watch to sunlight. 

After the lume charges, it can glow in the dark. There are no dedicated buttons on a watch to activate luminescence. It is an automatic process.

How Long Does A Watch Lume Last?

If you apply more coats of luminescent materials, the lume will last longer after being completely charged. Most lume-painted timepieces can be fully charged in 30 minutes or less under ideal lighting conditions. They can last anywhere between 30 minutes and eight hours once completely charged. 

Some watches have the capability of glowing in the dark for longer time periods.

 Frequently Asked Questions [FAQs]

How Does Watch Lume Charge?

Answer: You need to simply expose your watch to a light source, preferably one that emits UV rays, to “charge” the lume in your watch.

How Long Do Luminous Watch Hands Work?

Answer: The hands, numbers, and dials are painted with this non-radioactive substance, which glows in the dark by absorbing and reemitting light. The glow typically only lasts around seven hours in darkness, which is a drawback when compared to the lifespan of radioactive elements.

How Can I Tell If My Watch Has Radium?

Answer:  Picking up a basic Geiger counter is the simplest approach to determine whether a watch is radioactive. You can use this to determine for sure whether a piece is radioactive or not.

How To Extend Lume Time?

Answer: The best way to extend lume time is to apply thick coatings of lume on your watch. In that way, the lume will be in effect for a longer period of time. In addition to that, the longevity of lume in your watch will also be greater.


In this article, we covered almost everything there is to know about watch lume. If you have bought a new luminous watch, you may find it helpful.

We have tried to answer all the questions that may come to your mind related to these watches. So, we sincerely hope that you have found this article to be helpful.

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