During World War I, pocket watches gave way to wristwatches: a likely battlefield scenario was a soldier groping through his uniform for access to his pocket watch. How much more convenient it became to somehow tie his watch to his wrist.

At about the same time, someone discovered that the dials of these new wristwatches, as well as pocket watches, could be seen more readily if the dials were painted with a luminous paint, a substance containing radium. Radium was practical as well as novel, and luminous watch dials rapidly became popular. It also was used on some clocks, including the new, trendy automobile clocks. The military also used luminous paint on instrument dials in tanks, ships, and aircraft. At home, we used it on glow-in-the-dark numbers for houses, theater seats, and luminous lamp-pulls.

The manufacture of luminous dials suddenly became a significant industry.

Around 1917, the Radium Luminous Materials Corporation bought up radium mines in Colorado’s Paradox Valley, and built an extraction plant in Orange, New Jersey. They shipped the ore to Orange, where the radium was extracted.  They built a nice new building nearby for dial painting.

Zinc sulfide, when mixed with radium, glows brightly. These two powders were mixed with a varnish to produce luminous paint. For the paper dials, the powders were mixed with a water-based paste.

Radium dial painting began in 1917, and over the next decade, about 2,000 people were employed in the work, mostly in three locations: Orange, New Jersey; Waterbury, Connecticut; and Ottawa, Illinois.

The paint was applied to the dials by girls who worked with very fine brushes. To keep the brushes nicely pointed, the girls would twirl the end of the brush in their lips. The girls were known to brush the buttons on their clothing to make them glow in the dark, as well as apply it to their fingernails and their eyelids. They carried it home to their families. Everyone thought it was amusing to see their hair and clothing speckled with the glowing dust. The story goes that one girl even painted her teeth with the paint, so that her smile would glow in the dark.

The dial-painting job paid well, and attracted young women from miles around.  It was a pleasant place to work, with large windows to let in the light. As the pay was on a piece-work basis, an ambitious girl could earn a nice income. The median income for girls at this time was about $15 per week. The average full-time employee at the Orange dial painting studio earned about $20 per week for painting about 250 dials per day. Most workers were in their mid-teens to early twenties. In 1919, 200-300 women were engaged in dial painting. By that time, the more centralized radium companies had made 2.2 million luminous watch dials.

Radium was thought to have health benefits, and was actually viewed as a miracle cure-all and an elixir of health. In addition, it had significant social-cultural appeal and became a status symbol. As the Radium Luminous Materials Corporation sold the radium for medicinal use, there were no doubts about its safety.          

After several years, however, people started to get sick. The first illnesses linked to this industrial radium poisoning came to light in Orange, New Jersey, beginning in 1922. The dial-painting girls were stricken with terrible diseases that had gruesome manifestations. At first, doctors misdiagnosed their illnesses as “ulcerative stomatitis,” pernicious anemia, heart disease, and even syphilis. The companies and public health officials did not believe that radium was the problem; after all, radium was good for you.

Solving the mystery was a complex task requiring brilliant detective work by several investigators. Clinically, the traces of radium that were ingested were not completely excreted. It seems that radium is very similar to calcium, and the body is tricked into absorbing it into the bone structure where it remains permanently, to do its radiation damage. Slowly the facts were pieced together, and radium was seen to be the culprit.

To make matters worse, back at the plant, after the radium was extracted, the remaining ore “tailings” consisted of a nice fine sand, so it was prized as a play-sand for children! Parents brought it home by the bushel for their children to play in and track it back into their homes. As the extraction process was not 100 percent complete, this sand still contained a significant quantity of deadly radium. The full physiological damage to those children has not yet been determined.

Further, a large quantity of the sand was disposed of as landfill in surrounding neighborhoods that were being developed. The harmful radioactivity remaining in the sand was discovered only about 20 years ago. As radium decays, one of the by-products is radon, an invisible, but harmful radioactive gas. Extremely expensive remediation was necessary. The contaminated soil had to be removed from scores of homes. It was filled into 50 gallon drums for disposal, but there was trouble finding a place to dispose of it, so the drums were accumulated on pallets in residential neighborhoods. But that’s another story.

Incidentally, the scientific information about radiation sickness that was painfully accumulated in New Jersey in the 1920s provided about all that was known at the time, and thus became the database for the subsequent investigations 25 years later at Hiroshima and Nagasaki.

The horological significance of all of this is: Radium (the Ra-226 isotope) has a “half-life” of 1,620 years. This means that after 1,620 years, it still will be half active!

Tens of thousands of these luminous dial watches and clocks are still around. In their cases, and under the glass crystals, the radiation hazard is not significant. However, the luminous paint tends to crumble with age.

The full story about this issue is detailed in Radium Girls, by Claudia Clark, published by The University of North Carolina Press, Chapel Hill, 1997. Although it was published as an industrial health document, it is a real “page turner.” It should be at your local library and is available through the NAWCC Library. The book also covers the health hazards of Benzene (Benzol), which was a favorite of the old watchmakers, and is recommended in the old classic watch repair books. Benzene is not only extremely flammable, but was found to be such a powerful carcinogen that it was actually removed from the retail marketplace. It is still used, however, as an important basic industrial chemical. When used industrially, employees now are required to wear protective “space suits.” But that’s also another story.

Another interesting reference is Deadly Glow: The Radium Dial Worker Tragedy by Ross Mullner, published in 1999 by American Public Health Association Publications. Note that both the Clark and Mullner books were published within the last few years and as public health references. Alert horologists should promptly take note and safeguard themselves and their families.

About the Author

Mel Kaye served in the U.S. Army Air Force as an aerial photographer in China, Burma, and India during World War II. As a chemical engineer, he worked with chemical coatings and nail polish, and has three U.S. patents. He is a past president of New Jersey Chapter 25. Mel is a frequent contributor to the Bulletin, both of articles and Vox Temporis material.