The Glow-in-the-Dark Watches That Also Killed People

We can’t see in the dark. That’s why it’s called “the dark.” And that can be inconvenient — if you’re walking around, you’ll bump into things, for example. So throughout human history, we’ve tried our best to bring light into dark places. Torches, light fixtures, flashlights, and increasingly, cell phones have all been our aides in navigating the world when the sun has gone down and we still need to figure out where we are and what to do. And also, what time it is.

Watches and now phones with light-up screens mean that you can always know what the time is, even if there’s no other light source around. That’s nothing new; LED clocks have been around since the 1970s and we’ve had plenty of other ways to similarly illuminate a clock face for decades. But a century ago, being able to tell time in the dark. . .  that wasn’t so simple. That’s why Undark was such an incredible creation. As explained in the advertisement seen here, manufacturers of timepieces could “apply [Undark] to the dials of watches and clocks” and never again will you have to “wonder vainly what time it is because of the dark.” Undark — this miracle material — “shines in the dark.”

And it was very popular. And, unfortunately, deadly. Take a look at that ad, and you’ll quickly see why: Undark was made of radium.

Radium, as we now know, is a radioactive element that causes cancer in humans. In the very early 1900s, though, the dangers of radium were not well known, and to make matters worse, some even believed that the substance provided some medical benefits. In the late 1910s and into the 1920s, some energy drinks contained radium and proudly advertised that fact. For example, there was a drink called Radithor, which, as CNN notes, “was simply radium dissolved in water.” it sold for about $1 at the time — about $15 today — and in large amounts: “its manufacturer claimed the drink not only provided energy but also cured a host of ailments” and also made men more virile in the bedroom. None of these claims later proved true, of course; rather the drink ended up claiming the lives of many of its biggest fans.

But the “radium is good!” trend spread well beyond energy drinks. The manufacturers of Undark similarly saw radium as something worth promoting; the ad copy starts with the phrase “The Power of Radium at Your Disposal.” Unfortunately, to make the glow-in-the-dark watches, that power had to be harnessed with precision — and this is what that looked like.

That’s a picture from the Chicago-Sun Times (via Buzzfeed) of someone demonstrating “lip-pointing,” the practice of bringing a paintbrush to one’s lips in order to create a finer point than you’d usually get. The watch manufacturers that used Undark would hire young women to paint the radium-laced material onto watch faces. The women, per Buzzfeed, “obediently followed the technique they’d been taught for the painstaking handiwork of painting the tiny dials, some of which were only 3.5 centimeters wide. The girls were instructed to slip their paintbrushes between their lips to make a fine point.” And because the painbrushes were dipped in radium, the women were ingesting a little bit of radioactive carcinogens with every brush stroke. 

At first, the women didn’t mind this — in fact, some celebrated it. The jobs paid well — two or three times what you’d get at other factory jobs — and also, it made you really cool looking. Buzzfeed notes that the women were, at first, called “ghost girls” because “by the time they finished their shifts, they themselves would glow in the dark. They made the most of the perk, wearing their good dresses to the plant so they’d shine in the dance halls at night, and even painting radium onto their teeth for a smile that would knock their suitors dead.”

But ultimately, the radium caused way more harm than good. Many of the women — later called “Radium Girls” — started falling ill. CNN explains:

In the early 1920s, some of the Radium Girls started developing symptoms like fatigue and toothaches. The first death occurred in 1922, when 22-year-old Mollie Maggia died after reportedly enduring a year of pain. Although her death certificate erroneously stated that she died of syphilis, she was actually suffering from a condition called “radium jaw.” Her entire lower jawbone had become so brittle that her doctor removed it by simply lifting it out.

Starting in 1925, many of the Radium Girls filed lawsuits against their employer, claiming that the employer negligently if not knowingly exposed them to the toxic materials. (The researchers working with radium-based paints and the like wore masks, gloves, and protective gear; the women applying the paint were given no such protection.) That first case was settled in 1928, and by then, manufacturers ended the practice of lip-pointing, and radium was only used with at least some level of protective equipment. The practice also led to the adoption of a number of occupational safety laws throughout the United States and beyond, particularly around the handling of radioactive materials.

For many of the Radium Girls, though, it was too late. As NPR would later report, “by 1927, more than 50 women had died as a direct result of radium paint poisoning.” And many who survived past that point had chronic migraines and jaw pain, and many certainly also later developed cancer as well.


Bonus fact: When the Manhattan Project explored the creation of nuclear weapons in World War II, uranium — not radium — was the key element. But radium played a small role, not in the labs, but in the propaganda efforts. In June of 1943, the government issued a memo to the press asking them not to discuss anything about “the following elements or anything of their compounds: polonium, uranium, ytterbium, hafnium, protactinium, radium, rhenium, thorium, deuterium.” Only the use of uranium needed to be kept secret. But as the AP later reported, “by surrounding uranium — the heart of the atomic experiments — with those other elements, all legitimate although funny-sounding, direct attention on uranium was avoided.”

From the Archives: Radioactive Red: The problem with dishware.