Published · By Adventure Man
Super-LumiNova is a non-radioactive luminous pigment based on strontium aluminate: it absorbs light and gives it back as a glow in the dark. It is brightest in the first minutes after charging, then fades gradually over several hours, and any spell in bright light charges it again, as often as you like.
RC Tritec, which makes it, calls Swiss Super-LumiNova® "the watch industry's first choice" (RC Tritec), and it is the lume on ours: every KOMPAS uses it on the hands and markers. This guide explains what the pigment is, why it glows, what the grade and colour codes mean, how it compares with tritium, and how to get the most from it. It is built from the manufacturers' own published information. We have not added measurements of our own.
What Super-LumiNova is
The story starts in Japan. In 1993 Nemoto & Co. invented LumiNova, a family of long-afterglow pigments that Nemoto says give "10 times brighter, 10 times longer afterglow" than the zinc sulphide pigments used before (Nemoto). In 1998 Nemoto and the Swiss company RC Tritec formed a joint venture to make the pigment in Switzerland under the name Super-LumiNova (Wikipedia summary).
RC Tritec says Swiss Super-LumiNova® is "100% manufactured in our family-run company based in Switzerland" (RC Tritec). Its own description of the job is simple:
"Swiss Super-LumiNova® guarantees optimum readability of a watch even in poor lighting conditions."
RC Tritec, Swiss Super-LumiNova®
How watch lume works
Super-LumiNova is photoluminescent, which means it needs light before it can glow. The active material is strontium aluminate doped with small amounts of europium and dysprosium. In simple terms, the crystal stores some of the energy from the light it absorbs and releases it slowly as visible light. That slow release is the afterglow.
"It works like a light storage battery, where light charges the battery and afterwards the light is continuously emitted."
Jon Quinn, WatchGecko, Swiss Super-LumiNova®, December 2017
- The kind of light matters. The pigments are excited by wavelengths from about 200 to 450 nm, which covers ultraviolet, violet and blue light (Wikipedia summary). Daylight and bright white LEDs contain plenty of that. A warm, dim bulb gives it much less to work with.
- The glow is strongest straight after charging. WatchTime describes it as beginning "very brightly, then steadily fades" (WatchTime).
- There is no fuel to run out. Charging and glowing cause no chemical change, so the cycle can be repeated indefinitely (Wikipedia summary).
The classic green version emits at around 520 nm (Wikipedia: strontium aluminate). That is one reason green lume looks so bright: as WatchTime puts it, "the human eye is most sensitive to that part of the visible spectrum".
Grades and colours
Super-LumiNova is sold in grades, which describe how strong the afterglow is, and in colours, which describe how it looks by day and what colour it glows at night.
| Name | What it means | Source |
|---|---|---|
| Standard Grade | The base grade | RC Tritec |
| Grade A, Grade X1 | Higher grades. They start at a similar brightness to Standard but fade more slowly, X1 most slowly | Wikipedia summary |
| Grade X2 | RC Tritec quotes "over 80%" more afterglow than Standard Grade after two hours in the dark | RC Tritec |
| Grade X2 GL | Announced May 2025; up to 87% more afterglow than X1 after 60 minutes, "depending on its body color" | RC Tritec |
| C3 | Slightly greenish by day, glows green | Oris |
| BGW9 | White by day, glows blue | Oris |
Colour affects brightness. Oris, which uses both, says "C3 is slightly more luminescent than BG W9", and RC Tritec qualifies its X2 GL figure by body colour. RC Tritec now also offers custom emission colours, listing green, blue, violet, white, pink, yellow, orange and ultramarine blue (RC Tritec).
How long does lume glow?
Brightest for the first minutes, readable for hours. WatchTime says the pigments release their stored energy "as visible light over several hours". How long you can actually read the time depends on four things:
- How much pigment there is. Larger, thicker deposits hold more. RC Tritec recommends an application thickness of up to 0.30 mm (Wikipedia summary).
- Grade and colour. See the table above.
- How well it was charged. Bright, blue-rich light charges it more than dim, warm light.
- Your eyes. Lume that looks faint the moment the lights go out looks brighter once your eyes have adjusted to the dark.
Manufacturers compare grades under lab conditions: RC Tritec quotes its figures at 60 minutes and at two hours. Lume on timepieces also has its own international standard, ISO 17514:2024, which sets test methods and requirements for photoluminescent deposits. We have not published afterglow measurements for KOMPAS. If we do, we will show the method alongside the photos.
Super-LumiNova vs tritium
Before photoluminescent pigments, lasting lume needed radioactivity. RC Tritec says radium-based zinc sulphide was used "until the early 1960s" and was then replaced by "the weak β-emitter tritium" (RC Tritec). Some watches still use tritium today, sealed as gas in tiny glass tubes known as GTLS.
| Super-LumiNova | Tritium tubes (GTLS) | |
|---|---|---|
| Energy source | Light you give it | Radioactive decay of tritium gas |
| Needs charging | Yes | No |
| Through the night | Bright at first, then fades | Constant |
| Ageing | No chemical change when charged and discharged | Tritium has a half-life of 12.3 years (US NRC), so tubes slowly dim |
| Radioactive | No | Yes, a weak beta emitter |
WatchTime reports that GTLS luminosity "is guaranteed for 10 years", and that tubes may keep glowing for more than 20. Neither system is better for everyone. Tritium suits someone who needs a constant glow at 4 a.m. without charging anything. Super-LumiNova needs light, but it contains no radioactive material and does not decay with age.
How to charge and look after lume
- Charge it before you need it. A spell in daylight, under a bright white LED or a UV torch works best, because they contain the blue and ultraviolet light the pigment absorbs.
- Don't worry about wearing it out. Charging does not use the pigment up.
- Look after the seals. The raw pigment is sensitive to long exposure to water and high humidity (Wikipedia summary). On a watch it sits behind the crystal, so keep the crown pushed in and have the water resistance checked when the watch is serviced.
Lume on KOMPAS
Every KOMPAS uses Swiss Super-LumiNova® on the hands and markers, under a sapphire crystal with anti-reflective coating on both sides. The dial is built around 12 five-minute segments inspired by the RAF sector clocks of 1940, so even in low light you read the time in blocks of five minutes rather than counting marks. Our guide to reading a 5-minute dial explains how.
See North in black or South in blue, both in stock at the time of writing, or every specification on the technical page.
Frequently asked questions
Is Super-LumiNova radioactive?
No. Super-LumiNova is a strontium aluminate pigment that glows after being charged by light. RC Tritec, which makes Swiss Super-LumiNova, describes it as free of any radioactivity.
How long does Super-LumiNova glow?
It is brightest in the first minutes after charging and then fades gradually over several hours. How long you can read the watch depends on the grade, the colour, how much pigment is applied and how well it was charged.
How do I charge the lume on my watch?
Expose the dial to bright light: daylight, a bright white LED or a UV torch work best. The pigment can be charged and discharged again and again without wearing out.
What is the difference between Super-LumiNova and tritium?
Super-LumiNova stores energy from light and needs charging; its glow is strongest at first and then fades. Tritium tubes glow constantly without charging because tritium is radioactive, and they dim slowly as the tritium decays, with a half-life of 12.3 years.
What lume does KOMPAS use?
Swiss Super-LumiNova® on the hands and markers, under a sapphire crystal with anti-reflective coating on both sides.
