When radioactive tritium won't do, Marathon turns to this proprietary material to see in the dark

If you've ever used a Marathon watch, you'll likely know about the brand's secret trump card. Unlike most other watches in the modern age, Marathon makes use of tritium tubes for its indices, which glow with radioactivity to help users tell the time in the dark.

It's something which has made these military-approved watches a hit for years, and acts as a quirky point of interest for anyone seeking to single the brand out from a very competitive crowd. And for those applications where Marathon can't use a radioactive material, it turns to a proprietary formula called MaraGlo.

Those scenarios include things like explosive ordnance disposal – the practice of finding, making safe and disposing of, bombs – where radioactive material simply isn't permitted. It's also found on the outside of some of its cases, sitting proudly on the bezel of dive watches which contain tritium inside.

What is MaraGlo?

So, let's get to it – what is MaraGlo? Well, for most of us, it probably helps to think of it in relation to another popular lume, Super-LumiNova.

In essence, the two are like cousins, in that both are applied forms of lume in a liquid form. MaraGlo uses a slightly thicker formulation, though, which helps to promote more of a luminous effect.

That's something we can observe elsewhere, too. A few months ago, on a trip to see the Christopher Ward HQ in Biel, Switzerland, I met up with the team at XenoPrint, who produce the luminous blocks used as indices on watches like the C60 Trident Lumière. That principle is much the same as the one used in MaraGlo – more matter means more lume.

MaraGlo vs Tritium

One of the biggest differences you'll notice with tritium and MaraGlo is the brightness. When you first step from light into dark, the MaraGlo will appear much brighter off the bat.

The counterpoint to that is that luminous effect of MaraGlo will run out after a period of time, much like Super-LumiNova. The duration will depend on how significant the initial charge was, but it will expire. Tritium doesn't do that, instead offering a low-level of consistent light at all times.

Crucially, though, it's not always an either/or decision. Some watches use both MaraGlo and Tritium – usually split among the indices and the lume pip on the bezel – but one can also succeed the other.

While talking with the team at Marathon to gain a deeper understanding of how this all works, they mentioned that MaraGlo can even be painted inside of the Tritium tubes. The team stressed that it wouldn't be as bright, owing to the smaller footprint allowing for lesser coverage.

Even so, it could offer a different lease of life for watches which have served their duty with tritium, and now can live an easier one with MaraGlo.

Everything fit for purpose

The overarching theme for the brand is one of using the right technology for the right purpose. That stretches beyond just lume – few brands can chat so candidly about watches surviving the effects of an EMP thanks to their mechanical construction, for example.

With watches now arriving which solely make use of MaraGlo, I imagine that's something we'll see more of in the future. But make no mistake – Marathon makes watches to serve a purpose, and if that purpose requires radioactive material to make it work, that's what you'll find beneath the crystal.