Information Concerning Radiation in Antique Watches
There are a lot of rumours and speculation concerning the radiation that can lie in wait for us in antique watches. Some of them are really ridiculous, and in some cases perfectly safe watches will be lost for ever in a rubbish dump because of these assumptions. The problem is in the lack of reliable evidence. The following will try to explain everything using specific examples, so that you can decide for yourself what is not dangerous, what is, and how to handle such objects.
A lot of radioactive watches have passed through my hands, both in my collection and in repairs and restorations. I have thus accumulated a small photo archive, by the example of which certain conclusions can be drawn.
Advertising article about the radium watch, 1917.
Where Does the Radiation in the Watch Come From?
There are three main ways in which radiation is found in antique watches…
1. Radium numerals and hands (most common).
The first luminous radium-based paint was produced in 1902. From 1905 onwards, this paint began to be used on a very wide array of objects – even Christmas decorations and children’s books were painted with radium. “Night-glowing watches” were widely advertised, and by the 1910’s wristwatches with paint-filled numerals became the standard for the military, and thus all the watches of the First World War had radium paint on the numerals and hands. See the table below for examples: Patria and Lancet. Radium was also used on watches with enamel dials, and it is these that usually shine the most.
By the 1930’s and 1940’s, the watch style had changed, but the standard of using luminous paint continued. For daily-use wristwatches less paint was usually used, but large chronometers with a large dial and numerals could emit radiation of up to 10,000 micron/h. See an example of Laco-Durowe in the table below.
Radium was rarely used in civilian watches of the post-war period due to its high cost, but despite this such watches are still not uncommon. Radium existed in special instrument watches until the mid-1960’s.
2. Radium covered dial plate
This type of radiation is the same as in type 1, except the entire dial plate is coated with a radium phosphor paint and printed over with black or metallic numerals for contrasting visibility. This makes it easy to detect if the dial glows in the dark for a long time (more than 10 hours) without contact with external light. With this type of contamination, the background radiation is usually strong due to the large mass of paint. However, it is very rare to find a radium coated dial plate in watches, and it is more commonly found in other devices.
3. General radioactive contamination of the case
If the object has been doused or soaked in a liquid with long-lived isotopes, or been in a zone of powerful radiation, etc. it will be completely radioactive. It could be a watch, some dishes, a car, clothes, or really anything else. This type of contamination has nothing to do with the design or origin of the watch, but is an induced state due to external contamination.
Radiation cannot ‘soak’ through the metal parts of the watch, but it could be in the dirt and dust that is clogged in the cracks. If this is the case, one should disassemble the watch down to the screws, and wash the parts clean of radiation. Much more radiation will contaminate the fabric of a watch strap that has been coated in radioactive dirt.
The most interesting thing is that this type of radioactive contamination is the most frequently discussed and most feared. Allegedly, a watch from a tank or plane will completely light up. However, I have not come across this type of radiation for many years, and have only seen radiation in the numerals and hands (type 1).
Conclusion: in 99% of cases, radioactive paint will only be found on the numerals and hands on the dial of the watch (type 1).
How Dangerous are Radioactive Watches Really?
It has been proven that when radium salts enter the mouth or lungs, the alpha radiation causes cancer. Alpha particles knock electrons out of atoms to form free radicals, which in turn disrupt the structure of healthy cells and change some of them into cancer cells. It is dangerous to inhale contaminated dust, and very dangerous to eat. Leaving hands unwashed after handling is also very dangerous.
At the very least, it is obvious that such a watch should not be carried with you all the time.
According to current standards, it is recommended that a watch with a background radiation of 200 micronrentgen is worn for no more than the 40-hour work week. This means that the whole of the human body is only affected by 200 micronrentgen for 8 hours a day. A military wristwatch with a new, safe paint on the hands and the original radium paint on the dial, would have a background radiation of 80-250 micronrentgen on the front. The back would be shielded by a metal plate over the dial, a thick movement, an anti-magnetic iron insert, and finally the back cover of the watch. Due to the devices shielding the back of the watch, this side would radiate about 30-70 micronrengen, which is less than the norm for an 8-hour working day.
It is up to you to decide to what extent you should avoid a radioactive watch. Some people might keep such a watch for years, while others will be in a hurry to rid themselves of it as quickly as possible. In any case, after taking off the watch for the day, place it in a tightly closed plastic container, wash your hands thoroughly, and make sure to wipe any areas where the watch has been placed with a damp rag (it is better to throw the cloth away immediately after).
Is it Possible to Remove Radiation from a Watch?
Yes, it is possible. The procedure is time consuming and requires careful preparation and maximum attention to detail. A special workplace is needed, lined with disposable rags/ papers, and the paint must be gently softened in a bath under the water (to ensure that no dust flies off) and finally removed with specially sharpened sticks. Gloves are required, and plenty of disposable rags/ paper. In 90% of cases, it is possible to remove the radiation completely or at least to a safe level. Due to the health risk, it is highly recommended that you do not attempt such a task, unless you have the relevant experience and expertise.
Many are of the opinion that watches lose their collectible appeal if stripped of their radium paint. A lover of military watches will appreciate that everything is original, even if it is dangerous. You should not wear 800 microns on your hand day and night, but if you only wear it sometimes, it will not cause you harm – so let it lie peacefully in your collection. I never remove anything from my watches, because I want everything to be original.
See an example of removing radium from an enamel dial.
Precautions to Take with Radioactive Watches
Dangerous radiation is contained in small specks of crumbling radium paint that falls from the numerals and hands on the dial. If the paint is darkened, swollen, or grey-brown in colour, this is a sure sign of radiation. Check out the visual guide of examples in the pictures below.
1. It is dangerous to remove the glass and open the dial, as dust from the paint could be inhaled, causing potential contact with the respiratory and gastrointestinal tract.
2. Keep well out of reach of children! We all know how much children enjoy putting things in their mouths, and radium will cause serious problems if ingested.
3. Wash your hands after handling radium paint, or a radioactive watch, do not be sparing with soap and water.
4. When storing the watch, wipe it with a slightly damp disposable cloth, dry it, and place it in a sealable plastic bag or box.
5. If you recognise your watch, or one that has similar features, it is recommended that you check it with a radiation dosimeter. Measure the background radiation closely from the side of the dial.
Note: this is not a complete list of precautions to take when handling a radioactive watch. Use your common sense when handling dangerous objects such as these.
Portable radiation detectors cannot measure particular Alpha radiation, as Alpha nuclei cannot pass through watch glass crystal. To remedy this, we measure Gamma radiation that was emitted from the surface of the watch glass crystal cover, as Alpha particles struck out Gamma neutrons from the glass matter. The Gamma rays themselves are not radioactive enough to cause harm, but even a small amount of derivative Gamma shows the power of the Alpha radiation that dangerously lies inside the watch.
Visual Guide to Radioactive Watches
Some examples of watches adorned with radioactive paint. See if you can find any that looks similar to your own watch – whoever is forewarned is armed!
PATRIA: A typical military watch of the 1910’s, WW1. This radioactive specimen was about 1600 microns. The paint has come off in a greasy layer, and now lies in flakes and dust particles underneath the glass. These particles are extremely dangerous!!
After cleaning the numerals and hands, the dial looks fresh and new and the background radiation has dropped to zero.
LANCET: A watch typical of WW1, this one stayed at 1250 microns. Pay attention to the crumbled remains of paint underneath the yellowed glass.
A military instrument watch and timer from the 1920’s and 30’s, this Leonidas was about 800 microns. Dials like this are dangerous, especially when without glass. Immediately cover it and place it in a sealable plastic box or bag.
Large aviation LACO-Durowe FL 23883 Beobachtungsuhr, 8000 – 1000 microns (the dosimeter went off the scale, so it was difficult to measure more accurately). This is one of the most radioactive watches of this brand! Similar large watches are the LANGE B-Uhr, WEMPE, IWC, etc.
LONGINES: Military type watch, 1942. This watch company is particularly expensive, and they spared no expense on the radium in the paint – about 2000 microns / hour!!
The same watch after cleaning and replacing the phosphor with new, safe paint. Zero radiation.
Who would have thought that the civilian KIENZLE watch would be 556 microns/ hour! The hands are already rusted from the impact of the active phosphor.
This watch is by the little-known company WEISCO. The radium paint is cheap, and the background radiation is not very high, at 236 microns/ hour.
JAPANESE SEIKOSHA, radiation at about 7000 microns/ hour. This was is very dangerous. Radium paint was often used in instrument watches up until the 1960’s.
Soviet “KIROVSKIE” K-43 military issue. 844 microns.
HANHART: military watch, 800 microns – dangerous. The numerals are the typical swamp-grey shade of radium paint.
GLASHUTTE: 850 microrentgen/ hour. You can see the darkened paint on the arrows.
Below are some typical military watches with radium coated numerals and hands. All of them emit radiation in the range of 200 – 500 microrentgen/ hour.
Civilian watch ATIMA-SPORT, 1940’s, 350 microrentgen/ hour. Dangerous radium paint on the hands and numerals.
“SPORTS” watch. Innocuous in appearance, but the hands and blackened dots on the dial radiate 400 microns.
The Soviet record holder is the old ZChZ diving watch. The numerals are deeply indented and filled with radium paint. It radiates 8000 – 12000 microns/ hour (it isn’t possible to be more precise than this, as the counter went off the scale).
If you are unsure what to do with a radioactive watch, send a photo of the dial to me via my email horological.underground@gmail.com, and I can advise you. Many radioactive watches will be on the wanted/exchange list, and there are some people who might be interested in purchasing your watch, so do contact me about that too if you wish. Most importantly, do not discard your watch, show it to a specialist first.
Additional Materials
Demonstration: Removing radium from an enamel dial.
Interesting information about the element Radium and radium dials (the page is in Russian but will be translated via Google).
Article about a botched radioactive watch restoration.
