What is Lume?

Rado's newest 2009 addition, the Sintra Automatic watch is composed of extremely hard ceramic, a steel inner case and titanium screws and clasp. The watch is streamlined, gliding smoothly from watch face to bracelet, widening and narrowing insync with Rado's iconic style. The traditional dial is easy to read, by day and by night as the hands are coated with lume.

What is Lume?
Lume is the substance that allows the hands to glow in the dark. Lume is short for lumious phosphorescent.
What is phosphorescence? A type of photo luminescence.
What is photoluminescence? (abbreviated as PL) is a process in which a substance absorbs photons (electromagnetic radiation) and then re-radiates photons. (Wikipedia) The photo luminescence is produced when the electrons in a molecule are stimulated by an outside energy source. Either ultraviolet light ("black light"), biochemical reaction (glow-sticks) or radioactivity. Once the electrons are stimulated they quickly return to their original state by emitting radiation, sometimes in the form of visible light.

So we are interested to discover how our lume coated hands work. A phosphorescent substance does not immediately re-emit the radiation it absorbs. The answer is in the involved study of quantum mechanics which I am not an possibly not able to go into at this stage. It is suffice to say that the slower time scales are related to "forbidden energy" state transition in quantum mechanics. Simply put, energy absorbed by a substance is slowly released in the form of light.

What are the most common phosphorescent pigments used today? Zinc sulphide and strontium aluminate.

Most watch manufacturers use strontium aluminate, marketed by the brand name Super-Luminova. This substance is non-radioactive and non-toxic photo luminescence. This technology was developed after the zinc sulphide substance. Being that strontium aluminate is ten times brighter than zinc sulphide, the latter substance was zoned out and currently is something of a novelty.

Watchmakers were on a constant quest to find a substance that allowed time to be displayed in the dark. The problem was initially solved by the chime of a minute repeater or sonnerie, a candle or an open dial. As soldiers of World War One, huddled in dark trenches listening to the roar of the canons , unable to guess the passage of time, the quest to find a glow-in-the dark substance intensified. Watchmakers suddenly remembered Radium, a discovery made at the end of the 19th century. Radium was radioactive and had the property of luminescence. Radium was used in the watch industry for many years, but abandoned in favor of tritium as a result of its high levels of radioactivity; however, too late for hundreds of "Radium Girls in the 1920's". These young girls were employed by US watch companies to paint the Radium and zinc sulphide onto the dials using a small camel haired brush which they pointed with their lips in between paint applications. They had no inkling that this greenish white glow-in-the-dark paint was lethal. Each time they ingested a small amount of radium - an alpha-particle emitter, chemically similar to calcium and thus a bone-seeker, the Radium was accumulating in the bone-marrow and causing bone cancer and other genetic damages.

Tritium, on the other hand is radioactive but in much lower levels than radium, was used until the 1990's. Then came a breakthrough Super-luminova, all the photo luminescence qualities of tritium, but not radioactive and thus less hazardous and more environmental friendly.

There is a distinct difference though. Tritium is permanently stimulated by electrons (betarays) which it emits when it spontaneously transforms into helium. Thus tritium can glow for dozens of years even in total darkness. (see inset) On the other hand Superluminova requires to be stimulated by either violet or ultraviolet light which at first is very bright, but then gradually fades after a few hours in the dark.

As with Super-Luminova the energy emitted by the electrons is stored at quite a stable level, resulting in light being emitted over a several hour period.

The Deadly Dials and the Glowing Girls.

In researching the various aspects of lume, I happened across The Radium Girls. I decided "The Radium Girls" need more than just a couple of lines in a blog about lume. These girls gave up their life for the "glow-in-the dark hands on dial effect" and a blog honoring their memories is the least I can do.

In 1898 Radium was discovered by a Polish chemist ,Marie Sklodowske Curie, and a French Chemist, Pierre Curie, in the pitchblende of North Bohemia and isolated as a pure metal in 1911.

The characteristics of Radium is crucial to understand the full depth of the plight of the Radium Girls.

What we know now about Radium:

• Radium is a solid Metal
• Atomic Number: 88
• Atomic Weight: 226 (heaviest of the alkaline earth metals)
• Radium is over one million times more radioactive than the same mass of uranium.
• Pure Radium is brilliant white, but blackens when exposed to air.
• Radium is luminescent exuding a faint blue color.
• Radium's decay product, radon gas, is radioactive.
• Radium is chemically similar to Calcium and is thus "bone seeker" replacing Calcium in bones.
• Radium is carcinogenic and thus inhalation, injection, ingestion or body exposure to Radium can cause cancer, bone decay and degeneration.
• Emitted energy from the decay of radium ionized gases results in sores on the skin and a host of other illnesses too numerous to name.

The Curie lab notebook has many interesting findings about the properties of Radium; however, the notebooks are too highly contaminated to be handled safely.
The perception of Radium in first decades of 1900's:
One of the hundreds of articles I found in regard to the almost magical healing properties of Radium. The Article I quote below is from the Appleton Post-Crescent, Saturday, February 28, 1920:
RADIUM AFFORDS MOST RELIEF IN CANCERS AND FIBROIDS
"The greatest successes encountered in the use of Radium for therapeutical purposes have come from the larger cities, the colleges and the more important hospitals...... Trained surgeons working with Radium specialists at General Memorial and Women's Hospitals in New York...The use of Radium is slowly but surely spreading to all portions of the country.... It will soon be possible for anyone to secure the advantage of Radium treatment."
Needless to say Radium was a hit in the 1920's for its medicinal powers as well as its eery luminescence.
U.S Radium in Orange, New Jersey was a defence contractor who was the major supplier of radio luminescent watches to the military. Over a hundred women were employed at the plant between 1917 and 1926. There main job was to paint radium-lit watch faces and instruments.
In 1917, Quinta, Albina and Amelia Maggia ,ages 16, 17, 18 got their first jobs. They were so excited to contribute to the family income and work together. Amelia died first, her body exhumed but her bones still glowed. I suppose you can say she suffered the least, Quinta and Albina, first became anemic as Radium replaced Calcium in their bones, their teeth fell out and bones began to rot.
The job at US Radium was easy enough paint the watch dials with "magical glow in the dark paint". There were a couple of easy rules given to the girls:
NEVER WASTE THE PAINT. NOT EVEN A DROP. The paint was expensive. To avoid wasting the slightest drop, the girls were told to point and clean the brushes with their lips. The mixture of glue, water and radium powder did not taste odd or smell funny and so the girls pointed the brush with their lips about six times per watch dial.
When four girls died between 1922 and 1924, the city health official became concerned that possibly there were some health concerns at US Radium. The Consumers League, formed in 1899 and fought for safer workplaces, and editor of New York World, Walter Lippman were alerted to the suspicious deaths of these young girls. The deaths were said to have been caused by other unrelated illnesses.
The girls at US Radium noticed something strange, when they blew their nose the hanky would glow, one girl glowed all the way down her back, another on her hands and another on her legs; however, they kept on placing the Radium paint on their lips to point the brush.
Grace Fryer, a former US Radium employee, jaw began to decay and she couldn't understand why. Finally a doctor suggested it might be her prior job (she was now a bank teller) had something to do with it. Something to do with it indeed and she decided to sue. It took two year of persistence and agonizing debilitating pain to find a lawyer who agreed to take her case - Raymond Berry. Four other girls ,all of whom were suffering tremendously, took part in filing a lawsuit, on May 18th,1927, against US Radium in a New Jersey court. They were Edna Hussman, Katherine Shaub, Quinta MacDonald and Albina Larice. They became known as "The Radium Girls" and requested $250,000 each.
The case went to court and Berry alleged US Radium knew about the detrimental effects of Radium, but did not inform the girls. The case was just in its infancy and US Radium's high powered attorneys pulled all strings to keep the case moving at snails pace. Meanwhile another girl ,Amelia Maggia, died and her body buried, Cause of death was said to be Syphilis, but a couple weeks before she died her dentist, Joseph P. Knef, removed her decaying jaw bone and ran tests to confirm high radioactivity, specifically radium necrosis.
The media got wind of the story, and all the while the Radium girl's conditions deteriorated so much so they could not even attend their second hearing in court. Marie Curie ,the discover of Radium, said she had never heard of such a disease, but one thing she knew, once the Radium entered the body, there was absolutely no way to get it out. The girls would die. She implored better methods for dealing with Radium. (Curry died from Radium poisoning in 1934). Although the girls were dying, Berry was determined to see their day in court, but the Judge adjourned the case, it later came to light that the judge himself had stocks in US Radium Corporation.
After extensive media coverage, political intervention and the unfailing efforts of Berry, Hamilton and Walter Lippmann, editor of New York World Newspaper, US Radium thought it best to seek an out of court settlement for the dying girls. The girls would receive $10,000 each and a $600 a year annuity while they lived, and all medical and legal expenses shall be paid for by US Radium. Berry was upset about the final amounts awarded to the girls, he felt US Radium Corporation got let off too easy.
The Radium Girls' death highlighted the need for greater safety precautions in other Radium factories, safety in the work environment and a huge milestone for the labor rights movement. Many Radium dial painters survived as a result of Grace Fryer persistence even in the face of powerful opposition. Grace Fryer died, but her memory lives on.