When choosing sports or outdoor watches, one of the key features is their readability in the dark. That is why we decided to test the luminosity of watches equipped with two different technologies – tritium capsules and luminescent coatings. Our tests compared the luminosity of four PRIM watch models, and here are the results.
Test Summary:
- The longest and highest-quality luminosity among our four tested models belongs to the PRIM SPORT TRITIUM 25 – WORLD TIMER, which uses tritium technology.
- Among the three models with luminescent coating, the PRIM PILOT DUAL TIME achieves the best results.
- The best option for maximum illumination and longest duration is prior exposure to sunlight, an LED lamp, or another source of daylight.
Tritium – Constant and Automatic Illumination
Watches with tritium capsules contain gaseous tritium in small glass ampules. This radioactive hydrogen isotope naturally emits electrons that illuminate the luminescent layer inside the capsule. The main advantage of tritium is its continuous luminosity, which does not require prior light exposure. This technology ensures good readability throughout the entire night without any “charging” by light. The downside is the gradual decrease in luminosity over the years, as tritium has a half-life of approximately 12 years.
Luminescent Coating – Requires Light Exposure
Luminescent paints, such as Japanese Super-LumiNova or Swiss Super-LumiNova, work on the principle of phosphorescence. These materials absorb light energy and gradually emit it in the dark. The luminescent coating is typically more intense than tritium in the first minutes after exposure, but its brightness gradually fades. The key to the longest possible luminosity is sufficient exposure to a strong light source, such as sunlight or LED light.
Conclusion
Both technologies have their advantages and disadvantages. If you are looking for consistent and long-lasting luminosity without the need for recharging, tritium is the ideal choice. On the other hand, if you prefer intense brightness for a shorter period after sufficient light exposure, luminescent coating will deliver very good results. Our tests confirmed that PRIM SPORT TRITIUM 25 – WORLD TIMER excels in luminosity thanks to tritium technology, while PRIM PILOT DUAL TIME is the best among luminescent models.
Whichever option you choose, properly selected PRIM watches will ensure reliable time visibility even on the darkest night.
Model Comparison:
PRIM PILOT DUAL TIME
PRIM MANAGER CZ EDICE 04
PRIM SPORT ADVENTURE
PRIM SPORT TRITIUM 25 – WORLD TIMER
TEST 1 PROCEDURE:
All models were illuminated with an LED lamp for 2 minutes.
Photo taken one minute after illumination. The luminosity is roughly the same across all variants (the PRIM SPORT TRITIUM 25 – WORLD TIMER and PRIM PILOT DUAL TIME dominate in luminosity).
Photo taken 15 minutes after illumination. The luminosity of PRIM SPORT TRITIUM 25 – WORLD TIMER is the highest, PRIM PILOT DUAL TIME is slightly lower but the highest among watches with luminescent coating. On the remaining two models, you can see that their luminescent indices barely emit any light compared to the tritium ampules and the PRIM PILOT DUAL TIME model.
TEST 2 PROCEDURE:
All models were illuminated with a standard lamp for 2 minutes.
Photo taken one minute after illumination. The luminosity is roughly the same across all variants (slightly lower than with LED lamp illumination, but immediately after exposure the difference is not as visible as after the subsequent 15 minutes).
Photo taken 15 minutes after illumination. The luminosity of PRIM SPORT TRITIUM 25 – WORLD TIMER is the highest, PRIM PILOT DUAL TIME is considerably lower but still the highest among watches with luminescent coating. On the remaining two models, you can see that their luminescent indices barely emit any light compared to the tritium ampules and the PRIM PILOT DUAL TIME model (compared to LED lamp illumination, this is truly very low luminosity).
TEST 3 PROCEDURE:
All models were illuminated with daylight for 2 minutes.
Photo taken one minute after illumination. The luminosity is roughly the same across all variants (compared to artificial lights, however, the highest across all models so far).
Photo taken 15 minutes after illumination. The luminosity of PRIM SPORT TRITIUM 25 – WORLD TIMER is the highest, PRIM PILOT DUAL TIME is slightly lower but the highest among watches with luminescent coating. The PRIM SPORT ADVENTURE model has its highest luminosity here (compared to artificial lights). The PRIM MANAGER CZ EDICE 04 as well, although the illumination here is truly minimal.
TEST 4 PROCEDURE:
All models were illuminated in sunlight for 2 minutes.
Photo taken one minute after illumination. The luminosity is roughly the same across all variants (the PRIM MANAGER CZ EDICE 04 is the weakest – same as in all previous illumination variants).
Photo taken 15 minutes after illumination. The luminosity of PRIM SPORT TRITIUM 25 – WORLD TIMER is the highest, PRIM PILOT DUAL TIME is slightly lower but the highest among watches with luminescent coating. On the remaining two models, you can see that their luminescent indices barely emit any light compared to the tritium ampules and the PRIM PILOT DUAL TIME model. However, all models emit the highest luminosity with this type of illumination.
The tritium ampules that glow on the indices and hands of our watches from the PRIM SPORT TRITIUM 25 – WORLD TIMER range have different properties than commonly used technologies such as luminescent paints. Thanks to the luminescent paint layer or tritium ampules, the indices are highlighted in low-light conditions or in the dark. The standard luminescent paint mixture is applied in various layers. It affects the luminosity and duration of luminosity, i.e. the emission of light absorbed from another light source. The luminescent paint emission is very intense after illumination compared to tritium ampules – see the photo taken immediately after illumination, approximately within 1 minute. The watches using tritium are on the right. The luminosity of watches with luminescent paint depends on the layer thickness, which is why the PRIM MANAGER CZ EDICE 04 has the lowest luminosity. The PRIM PILOT DUAL TIME model has 3D indices, which is why its luminosity is the highest.