Have you ever noticed how some watches glow brightly in the dark? That glowing material is known as lume, and it’s more than just a cool feature—it’s a vital component in diving, aviation, and tactical watches. But how does lume work? What types are used today? And why do some watches glow longer than others?
This article breaks down the science and history behind lume technology, and how to choose a watch with the best night-time visibility.
What Is Lume?
Lume is short for luminescence, the ability of a material to emit light after being energized. In watches, lume is applied to the hands, hour markers, and sometimes the bezel, allowing users to read time in total darkness.
How Lume Works
Modern lume works in two main ways:
- Photoluminescent (non-radioactive)
- Charges from light (sunlight or artificial light)
- Glows for hours after exposure
- Common materials: Super-LumiNova, C3, BGW9
- Radioluminescent (radioactive)
- Self-powered (does not need light to glow)
- Historically used radium (now banned)
- Modern versions use tritium gas tubes (safe and regulated)
Types of Lume and Their Brightness
| Type | Brightness | Duration | Safety |
|---|---|---|---|
| Super-LumiNova | 🌟🌟🌟🌟 | 6–10 hours | Very Safe |
| BGW9 (white-blue) | 🌟🌟🌟 | 5–8 hours | Very Safe |
| Tritium Tubes | 🌟🌟🌟🌟🌟 | 10–25 years | Safe (regulated) |
| Vintage Radium | 🌟🌟🌟🌟🌟 | 20+ years | Hazardous ☢️ (now banned) |
Which Watches Use High-Performance Lume?
- Dive watches (e.g., Seiko Prospex, Citizen Promaster)
- Pilot watches (e.g., Laco, IWC)
- Tactical/Military watches (e.g., Marathon, Luminox – uses tritium)
- Field watches (e.g., Hamilton Khaki Field)
Tips for Buyers
- If you want maximum brightness after short light exposure: Super-LumiNova (C3) is best.
- For consistent glow without recharging: choose Tritium tube watches.
- White lume glows blue, green lume glows green/yellow — both have pros and cons depending on contrast.
Did You Know?
Early 20th-century watchmakers used radium paint, which caused serious health issues for workers. Today, all modern lume is safe and heavily regulated.
