Don't Lick Dials
If I burn, we all burn - a simple discussion about lume in vintage watches, its safety, and why I steer away
I feel like lume is somthin’ not a lot of people talk about in the vintage watch world.
The consensus seems to be tritium is fine, radium is eh, and no lume dials are rare. Other than that, there’s not much consideration for actual research into the relative safety of the compounds that glow.
Today we’re pushing an article to create a little conversation about lume - sorta a mix between an op-ed and a research paper.
In reality, there are many factors to be considered with lume in vintage watches, and it seems there's a lack of professional decisiveness on the matter, but mere opinions on forums.
Diving deep into this topic is gonna get nerdy, and as a little side note, I actually have a degree in biology specializing in forensic chemical analysis. I think there’s a level of arguable ethos with my opinions here today.
Radium Caused Serious Health Issues for Watch Manufacturers
Radium was 'discovered' as physicists were researching different compounds and their uses. This chemical element was being utilized prior to any real knowledge of radioactivity and its effects on humans was realized.
Often, those who worked with radioactive compounds prior to knowing their effects died young of cancer, but their work was still instrumental in pioneering research.
Marie and Pierre Curie discovered the element, and it was soon marketed as a medical remedy. In the era of snake oil salesmen, radium could be found in toothpaste, ointments, water, pills, nail polish, really anything you could think of. There was even makeup containing radium that was said to make your skin ‘glow.’
Sick at the doctors? Take some radium. Digestion issues? Wear a radium infused corset. Want to be able to read your watch in the dark? Just apply some radium to its dial...
A Rolex with small radium plots
This brings us to the Radium Girls. Young women who worked in American dial painting factories were instructed to mix radium power (meaning this radioactive dust was in the air) with luminescent paint and apply it to watch dials.
At the time, they were instructed to lick the radium coated brushes for precision - after all, it was ‘common knowledge’ that radium was either harmless, or medically beneficial.
These women started complaining of achy bones, teeth falling out, headaches, sickness, etc.
One day, while at the dentist, one of these girls had her jaw fall off into the dentist's hands. The dentist (as one does) put her jaw adjacent to X-ray film where he noticed an image of the jaw developed. That's when it became known that radium may not be a miracle medicine, but the complete opposite. There's even some evidence that the watch brand heads knew of this detriment but kept it under wraps for years.
The licking technique demonstrated above - just performing this once would put an individual at a risk of developing cancer
What We Now Know
In an attempt to explain this phenomena scientifically, we must first look at the specific formula of radium used in these watches.
The isotope of radium found on virtually all watch dials from the era experiences a half life of 1600 years. This means that it is virtually as radioactive today as it was the day the watch was cased in the 1950s. Those with strong watch related opinions online are often under the belief that because the watch is old, it is less dangerous - but that is simply not factual.
The radium in these watches never glowed itself, but its ionizing energy excited electrons in luminescent paint that would cause glow. In theory, if you added more of this paint, the old radium would make it glow just as bright as it once did.
Look familiar? This pic is in another article - our hand-applied American-made radium-packed specimen "RaSWISSRa"
I’m sure most of you know about the Rolex GMT bezel recall where the Bakelite bezels were packed full of the substance.
Tritium
Medical advances saw radium replaced by tritium, which is usually regarded as the most ‘common’ source of lume in vintage watches. While radium was used until the 1960s, tritium saw use into the 2000s.
Tritium is simply a radioactive isotope of hydrogen. ‘Typical’ hydrogen contains just one proton at the nucleus, while tritium has one proton with two neutrons. This difference in nucleus creates an unstable molecule, and thus, a radioactive substance.
While modern uses of tritium are still commercially available and typically marketed towards military application, we can hark back to an example like this 1960s field watch to see when the substance was first being utilized.
Like radium, tritium emits electrons through decay that excites phosphor in the same vicinity causing visible light to be emitted. It’s important to note that visible light in this sense is just non-ionizing (harmful) radiation.
What is the real harm in tritium? Really nothing. In theory, it emits radiation, but it is such low energy that virtually none of it penetrates the watch components enough to cause damage.
Interestingly, collectors an scientists alike have studied this substance in watches, and it’s been said that tritium emits background levels of radiation when watches are measured with Geiger counters.
Still, Swiss watch companies opted for luminova over tritium in the late 1990s because of radiation.
Time To Sell Your Old Watches?
The answer we've all been waiting for...
Should you be worried about lume?
No, not really, but maybe.
You see, the radiation emitted by radium watches (especially the isotope commonly used) is primarily in the form of alpha and gamma rays.
Alpha rays barely penetrate any solid, and are virtually blocked by steel. This means that a Geiger counter on the crystal will give alarming reads, but one on the caseback will be virtually safe (yet still more radiation compared to tritium). While the radiation is still ionizing, it isn't the most serious, and not comparable to touching your skin to the compound.
Now if you're diligent with your health, perhaps you'd like to stay away from radium.
That brings me to the point of opening the watch up. Radium is essentially safe to wear on occasion, but the moment you open the caseback, or pop out the dial, it becomes extremely unsafe.
Radium particles can get in the air, and if any are consumed, you'll have ionizing compounds in your body (unless you live to be older than 1600).
The body treats these compounds similar to calcium, so it will be deposited in your bones.
Additionally, radium decomposes to radon gas, a cancer causing dense gas that is easily inhaled into the lungs. Owning multiple radium-filled pieces in a small, poorly ventilated room is not ideal, and could pose a health risk in the long term.
If radium will burn a dial, what would it do to your body?
As an additional note, I highly recommend you check out this article that provides a relatively recent update on the topic.
Tritium is objectively more safe to wear when it comes to vintage pieces. With radiation emitted being practically the same as background levels, I wouldn’t worry much if your daily is filled with the stuff.
Personally, I do not own any vintage watches with lume. Granted, I own a Tank Louis, Santos, and a Seamaster, but I still don’t feel comfortable with anything radioactive on my wrist. I recognize the relative safety of tritium, and I love the character of a radium dial, but I feel no lume dials add a sense of practicality and modernity to vintage watches.
Worry Not
Now I wouldn't run to pickup a dial coated in radium, but one with small plots, or perhaps a little burn won't kill you.
If you're a watchmaker though, be very careful around the stuff, radioactivity is nothing to mess with.
Life is too short to not enjoy watches because of their lume. After all, some of the hottest pieces out there have radium, and still fetch millions at auction.