As soon as I got my Panerai Luminor, my face lit up with curiosity as parts of the dial started to illuminate. I had no idea what it was, but after I found out it was called “lume”, I often wondered how long it lasted in dark environments so I decided to run a test.
On average, watch lume (luminous phosphorescence) lasts around 5.76-hours in dark environments. A fully charged watch lume can last anywhere between 3 to 8 hours and up when used.
Read on to view my experiment using my own watches on how long watch lume lasts with my thoughts about watch lume.
How Long Watch Lume Lasts: My Experiment
Through my experiment over a span of several days, I found that a fully charged watch lume on average lasts around 5.76-hours in dark environments where lume is completely visible: the highest time being over 8-hours and the lowest being just under 3-hours.
To test how long the watch lume lasted, I placed one of my favorite watches that have lume, my Panerai Luminior Chronograph Daylight, in my closet, which is one of the darkest rooms in my house. As soon as I placed my watch in the closet, I set a timer and checked up on it every 30 minutes to see if it’s still glowing.
Since this Panerai Luminor Chronograph Daylight was made before 2009, the timepiece is equipped with tritium lume, which is an isotope of hydrogen that’s useful for lume but is weaker than their modern-day “superluminova” lume found on their new watches produced after 2009, which directly affects the tests.
In addition, I made sure to fully charge the lume on the Panerai watch to produce the most accurate test. The lume lasts longer with it being fully charged.
| Lume Test Number | Time (in hours) |
| Test #1 | 8.33 hours (from 11:51 AM to 7:10 PM) |
| Test #2 | 4.25 hours (from 10:00 AM to 2:16 PM) |
| Test #3 | 6.25 hours (from 3:16 PM to 9:31 hours) |
| Test #4 | 7.1 hours (from 8:34 AM to 3:40 PM) |
| Test #5 | 2.9 hours (9:09 AM to 11:58 AM) |
After running several lume tests with my Panerai, I found that watch lume can last anywhere from 3 to 8 hours when it’s fully charged, and the total average of lume time was
When I started this experiment, I wasn’t sure how long watch lume was supposed to last, so I didn’t really have any expectations going into it and thought the lume would last only an hour or two: I was completely wrong. I realized this during test #1.
I set up the watch in my closet near noontime, and when I kept double-checking it to see if it was still glowing, I was thoroughly surprised to watch it glow for a little over 8 hours. I thought to myself “Is the lume ever going to run out?” and a little over 7 PM is when the lume stopped. You should’ve seen the look on my face around the 6-hour mark because I looked so surprised at how long the lume really lasted on this Panerai.
Since I saw the lume glow for over 8-hours during the first test, I was expecting the second test to last around the same time or last even longer. However, I was wrong and the fully charged lume lasted for 4.25-hours, which is substantially less than the first test. I thought this was a mistake, but I realized that this was part of the testing.
For the third and fourth tests, I had no idea what to expect because the first and second tests produced different times. However, I was pleased because the watch lume lasted for a significant amount of time: the third test being 6.25-hours long and the fourth test being 7.1-hours long.
And for the fifth and last test, I was just as shocked as the first test I ran for watch lume. For this test, the lume lasted for just 2.9-hours, which is the lowest out of all of the tests. Nonetheless, we have to keep in mind that the watch is a little over 14 years old and hasn’t gotten serviced in a year or two, which may be why the lume time started to fluctuate from test to test.
If you want to know my opinions about this Panerai Luminor Chronograph Daylight, then you can check out my full in-depth review article by clicking right here.
How Is Watch Lume Recharged?
Watch lume is recharged under direct light. Watch lume usually takes around 10 to 20 minutes to fully recharge, and the most optimal forms of direct light for recharging lume are sunlight, UV lights, or lamps.
This is how I recharged my watch lume from test to test in my experiment. I would take my watch and place it carefully on my windowsill for around 10 minutes more or less so the sunlight would directly charge the lume parts on the dial. I knew it was fully charged when the lume parts of the dial started to glow brightly even in the daylight.
This not only works for my Panerai watch but for all watches that have lume in general. If you hold any watch with lume under direct light for ten to twenty minutes, then it will charge the lume quickly and efficiently.
Does Watch Lume Wear Out Over Time?
Watch lume does wear out over time when used regularly and lasts for fifteen to twenty years. Once the watch lume is completely used out and is not recharging under direct light, the timepiece needs a new coating of lume (AKA “reluming”).
To really find out if lume wears out over time, I contacted a store called “Gold Creations”, which is a jewelry and watch store where I usually get my watches serviced in my local mall, and I asked them if watch lume wear out over time. They said to me,
“Watch lume wears out over time and can last from fifteen to twenty years. You’ll know when your watch lume needs reluming if it’s not charging in direct light.”
-Gold Creations
I find this to be a really long time period, which is something I like about watch lume since it can be very useful. This means that you won’t have to worry about getting your watch relumed for years if it’s brand new.
Whether you’re someone who is just getting into watches or someone who has been in this hobby for years, it’s helpful to know how long lume lasts, how it’s recharged, and how long it lasts over time. Lume can be a great tool to use on a timepiece that is often overlooked.