At the recent FHH Roadshow in Paris, I saw a rare vintage Blancpain Fifty Fathoms No Radiation on a wrist and I was curious about why the watch had a ‘No Radiation’ symbol featuring so prominently on the dial.

Blancpain Fifty Fathoms Aqua Lung ‘No Radiation’

Launched in 1953, the Blancpain Fifty Fathoms is credited as being the first professional dive watch (see Blancpain Fifty Fathoms Documentary: Story Of The World’s First Diving Watch (Video))

To maximize legibility underwater, the first Fifty Fathoms models had the hands, numerals, and indexes painted with a radium-based lume (see Radium Watch Dials And Radium Girls: Who Would Have Thought ‘Eating’ Radioactive Material Was Deadly?).

This continued into the 1960s; however, thanks to the Cold War, people became more conscious of the health risks associated with radiation, and the highly radioactive radium lume was replaced by tritium, which, while still radioactive, is much less so than radium and doesn’t pose a risk to health.

To put the radiation of tritium in perspective: the most common and abundant isotope of uranium is uranium-238, which has a half-life of 4.5 billion years; the radium-226 used in watch lume like the first Fifty Fathoms models has a half-life of 1,600 years; tritium has a half-life on just over 12 years.

In the early 1960s, Blancpain replaced the radium lume on the Fifty Fathoms Aqua Lung with tritium lume. And to highlight this new healthier version they placed a bright “No Rad” or “No Radiation” symbol boldly on the dial.

Blancpain Fifty Fathoms Aqua Lung ‘No Radiation’

For a 60 year old watch this Blancpain Fifty Fathoms Aqua Lung ‘No Radiation’ looked in excellent condition and still looks good today.

For more information, please visit www.blancpain.com/en/collections/fifty-fathoms-collection

You might also enjoy:

Blancpain Fifty Fathoms Documentary: Story Of The World’s First Diving Watch (Video)

Radium Watch Dials And Radium Girls: Who Would Have Thought ‘Eating’ Radioactive Material Was Deadly?

Blancpain Fifty Fathoms Automatique: Time to Move on From the Rolex Submariner?

Blancpain Tribute To Fifty Fathoms MIL-SPEC: Ready For More Than A Quick Swim