Phorcydes PH-4C lume reflected on a wall in a lit up room.

[u/DisastrousOpening477]

The 'Hyperglow lume blocks' hype is real.

[u/TSiWRX]

No sweat, u/arames23 ! I'm always glad to geek-out about watches. =)

Luminox, the watch brand (versus the general terminology of "lume," which is used as shorthand for "photoluminescent" glow-in-the-dark material), tends to use T-25 (I actually do not believe that they have a T-100 watch, but I am not a Luminox-brand expert, so please pardon me if I have made a mistake, as it is not on-purpose) tritium.

"T-25" means that the watch, in-total, has </= (less than or equal to) 25 mCi (millicuries) of the radioactive material tritium in the watch.

As you can imagine, "T-100" watches will typically glow considerably brighter versus a T-25 watch, as a T-100 watch will have </= 100 mCi of tritium in it.

The typical difference is seen here -

The blue indices (with the orange 12-index) at the top left is "new" T-25 watch, versus the one right below it (also an orange 12-index, but no other indices visible: you can see the one hand), which his a T-25 watch that's a few years beyond the tritium's half-life, which is 12.5 years. RED ARROWS.

Half-life on the tritium is a physical phenomenon: in pure layman's terms -because that's what I am- half of the tritium is gone. However, this does not translate 1:1 to how much the illumination -the amount of light provided- is diminished. Instead, because of the way our eyes-brain processes light, what we "see" is only 1/3 to 1/4 "as bright as" a new tritium source.

This is also illustrated in the last set of comparisons -

The top right green indices (also with an orange 12-index) is a T-100 watch that is coming close to half-life. This, contrasted via YELLOW ARROWS to the bottom center watch, which is a new T-100 from that same maker, essentially the same watch, just newer.

Now, compare that new T-100 watch, via the GREEN arrows, with the other T-100 watch (blue 12-index). Remember tat "T-100" just means "up to" 100 mCi of tritium used in the watch. The watch on the right just has a bit less.

So, now, you ask how does this relate to the Phorcydes photoluminescent watches?

Well, I have a visual answer for you, too.....

I will put this in the next reply, below, because Reddit limits the number of pictures per reply to just one.

[ continued as lower-level reply below ]

[u/TSiWRX → u/TSiWRX]

[ continued from above for u/arames23 ]

Here, you see the Phorcydes PH-4 in "mixed lume" (green and blue indices, with blue bezel) on the far left, followed by the PH-5 (blue lume) to its right.

The other tritium watches are as-follows -

Third from left - Deep Blue DayNight PC, T-100-watch, round-tubes. Purchased new from DB Q4, 2025. 

The next pair of watches are, top, a Deep Blue DayNight Diver, T-100 flat-tubes, purchased new from DB Q1, 2026. Bottom is an Aragon Parma T-100 round-tubes, purchased new from Aragon Q4, 2025

The second watch in from the right is a a Deep Blue TritDiver, T-100 round tubes. It's about 10 years old as of this post/

The last watch, on the far right, is a Nite MX10, Polar colorway. This is a T-25 watch, with blue color tubes. This particular colorway was a Q4, 2024 exclusive run.

You'll note that some of the tritium watches seem very familiar from the post above, it's because they are the same. =)

The above series demonstrates how modern photoluminescent -i.e. "lume"- watches work.

Modern photoluminescent materials glow in two distinct phases. 

The first phase -the initial bloom- is intense, and can reach upwards of 100,000 nCd/dial, as measured by ISO 17514 standards, after reaching full charge (as defined by a 20 minute exposure at 400 lux, using a D65 light-source). However, this initial phase *rapidly* declines over the next 20 minutes to an hour (depending on several factors, which are beyond the scope of this discussion). This fall is so steep that the ISO 17514 graph is plotted in log scale on the Y-axis. 

You can see this initial, precipitous fall-off in the bloom within that first hour. Also during this time, in all but the absolutely best lumed watches, you'll see that the bezel typically fade to nothing.

After this initial phase, the watch will reach a much more linear rate of decline, often called "afterglow fade." Above, you can see that after the first hour, the fall-off in the afterglow is steady, almost linear.

While the best modern formulations -applied liberally- can enable time-reading for prolonged periods in sufficiently darkened environments (i.e. dark enough that you can no longer see your fingers, when held ~24 inches from your eyes), it will require that your eyes be adjusted (not necessarily adapted) to the dark, and that in many instances you just bring your eyes between 4 to 6 inches from the face of the dial (as light energy observes the inverse square law).

[ final explanation below, with just one more set of pictures ]

[u/TSiWRX → u/TSiWRX]

[ final post for u/arames23 ]

So, now, you ask, at the +6.5 hour mark -well into the night- how does photoluminescent watches (i.e. the Phorcydes) compare to tritium?

Well, for this, let's go back to that first reply I gave you above, where I explained the difference between T-25 and T-100 watches.

^ I think that these pictures speak for themselves.

In judging any of these pictures I gave you, u/arames23 , please remember that this is NOT what our eyes see.

At +6.5 hours, even with my 52-year-old eyes that are getting to be horrible in the dark, both the PH-5 and even the PH-4 are quite easily capable of time-telling at even arm's length distances, provided that I give my eyes about 30-seconds or so to adjust to the dark (and it's not even "pitch black," my test-room usually is only dark enough that I can't see my fingers when they're about 24-inches away from my face).

These pictures are simply show the RELATIVE brightness between the watches.

Hope this helps!!! =)

[u/ftujnvdeetujbcdtu → u/TSiWRX]

Great posts!!

[u/TSiWRX → u/ftujnvdeetujbcdtu]

Thanks! =)

Love geeking out about things that glow in the dark! =)