The problemPrevious non-radioactive luminous compounds definitely lacked in their ability to stay bright enough through a night, under conditions when it wasn't totally dark, because when it's nearly dark is when you need the best contrast.
Pure tritium activeded compounds have the problem that when you go from a bright to a dark place, they usually don't glow bright enough. Mixing another substance with them which handles the first 30 min or so works wery well though.
It's easy to see that Luminova behaves sort of like a tritium/regular mix initially. Likewise it stays bright enough through a single night if it's been subjected to enough light during the day. But I was curious about how it would behave during the hardest conditions.
I think winter near (well, relatively at least) a pole is the toughest challenge, because even if the sun nominally is over the horizon (and it mightn't be for weeks at a time), it's not likely shine brightly, nor is the watch likely to be worn outside your clothing even if it does. And in addition to this, neither in- nor outdoors is it certain it will be so totally dark at night as it gets nearer the equator at night.
The testSo I did a little practical, informal test: Watches were worn normally for two days, saw no daylight except through windows and even in office illumination mostly were worn under a shirtsleeve. Then they were put away one evening in a totally dark place and only brought from it during practical darkness (as in barely enough to get around in in a familiar space or darker).
- First morning: Of course no problem to read the time. Comparable to tritium.
- First evening: Legible, but not as bright as a watch with about 10 years old tritium compound (which as I get older is about when I think it's time to replace it).
- Second morning: Perfectly legible - provided your eyes are dark adapted. Otherwise only if you brought it to total darkness.
- Second evening: Legible with difficulty.
- Third morning: Like the second morning, only still weaker.
Note that Luminova is not fully charged just because it glows brightly, which it can do after only 20 s outdoors in daylight. It takes approximately 30 min for it to reach its full charge.
I sure hope Luminova will also prove to stay usable a long time, both in years and in number of charge/discharge cycles.
Document created 2002 Jan 31 (Another article from the archives. The watch with tritium index and hands had it replaced with Luminova when it was next serviced and I've never missed its tritium.)