None of the material on this page constitutes or should be taken as advice about handling watches or anything else with radium based paint. I relate what I have found out about the effects of radium based luminous paint and my own practice in dealing with old luminous paint on watches solely for the purpose of providing information and this must not be construed as advice or recommendations. If you own or plan to work with anything bearing or containing radium paint at your own risk you should read up as much as you can and come to your own conclusions, and if in any doubt, leave well alone.
Luminous Paint on Watch Dials and HandsCopyright © Notice
There are two types of luminous paint that a watch collector might encounter, modern luminous substances that are quite safe, or earlier radioactive paints, mainly based on radium, that need treating with caution.
If you "consult" the internet watch forums you will find that some some people get very exercised about the dangers of radium paint, while others don't know what the panic's all about. I have even read a comment that the radiation from radium paint is less dangerous than a mobile phone. I think it is safe to say that those who don't know what the panic's all about simply don't understand the subject and should be ignored, and given that radium paint was banned in the 1950s on health grounds, when attitudes to risk were less precautionary than they are now, to say that radium paint is less dangerous than a mobile phone (which as far as I am aware still haven't been banned on health grounds) is both plain wrong and, in my view, highly irresponsible.
Caution is rarely a bad thing, but it doesn't get you any kudos on internet forums. However, here I can take a more measured view of the dangers and precautions without being flamed. My view is that it is not necessary to avoid radium paint altogether, but it is very necessary to understand it and the risks it can pose, particularly if you are going to work on old watches that may have this type of paint.
Modern Luminous Compounds
Modern luminous compounds are safe and fall into two categories.
- Light charged compounds
- "Safe" radioactive compounds
The first category, light charged or "afterglow" luminous paints charge up in sunlight, and in artificial light to a lesser degree, storing ultraviolet light energy like a battery and then releasing it as visible light in the dark. (The release of visible light also happens in daylight, you just can't see it.) These paints tend to initially glow in the dark very brightly, but the bright glow soon fades. Super-LumiNova is probably the best known of this group of compounds, which also includes Luminova and Lumibrite.
The second category, safe radioactive compounds, is very similar in principle to radium based paint but uses radioactive materials such as tritium gas contained in small glass containers. Tritium gives off beta radiation which cannot leave the glass container and is far less dangerous than the gamma radiation given off by radium. Watches with tritium luminous compounds glow all the time, like radium compounds, and do not need charging up in sunlight, but are safe as long as the glass container is not broken. If you are unfortunate enough to break a container of tritium, just stand clear and let it disperse into the atmosphere, opening widows and doors if necessary. This is also quite safe, there is always a small amount of naturally occurring tritium in the atmosphere escaping from natural sources in the ground, which is where the tritium in your watch came from in the first place.
Radioactive Luminous Paint
Some vintage watches, especially military watches, had the numerals and hands made luminous or "glow in the dark" by painting them with "radioluminescent" paint where the glow from the paint is caused by nuclear radiation. This paint was not like the luminous compounds commonly used in today's watches, most of which charge up in sunlight and lose their glow over a few hours. The luminous paint used on Great War (WW1) era trench watches was made with a mixture of radioactive radium and zinc sulphide. The zinc sulphide glowed brightly when hit by radiation from the radium. This paint glowed all the time, day and night, without needing exposure to sunlight, and continued to glow even when stored away from the light in a drawer. However, after about three years the zinc sulphide becomes burned out by the continual radiation bombardment and no longer glows in the dark - but the radium has hardly changed and is still there, emitting radiation.
Article from November 1915
The article shown here was published in November 1915 during the Great War. If a soldier already had a perfectly serviceable pocket watch or wristwatch that simply wasn't luminous, then this could be upgraded to a luminous watch by putting dots of radium paint on the dial next to the hour numerals, and changing the hands to the luminous radium type, as described in the article shown here from November 1915. A pocket watch could be upgraded for 10 shillings, a wristwatch for seven shillings and sixpence. You will notice that the article says that the "best quality of luminous paint" will last about three years. If you find a watch with the original radium based paint like this you will find that it no longer glows in the dark because the fluorescent material has long since worn out but the radium, which has a half life of about 1,600 years, will still be very nearly as radioactive as when it was new and you need to be aware of this and take some basic safety precautions.
Luminous radium paint on dials was first used around 1910, before the dangers of radioactivity were fully understood. Although health problems in workers applying radium paint to watch and clock dials were noticed in the late 1920s, radium paint continued to be used. There wasn't a suitable safer substitute available, and military authorities continued to specify radium based paint for important applications such as compasses, instruments, gun sights, and, of course, watches. However, in the 1950s it was realised that the dangers to health were significant and radium paint was phased out.
Air Publication 112G-0815-1 July 1966
Although the dangers of radium luminous paint had been identified by the 1950s and alternative luminous compounds were being used or developed, the use of radium based luminous paint didn't stop overnight, nor were all the items with paint taken out of service at that time. There was nothing else that gave such a bright and lasting glow in the dark effect, there isn't anything even today that compares to the the brightness of luminous radium paint. Radioactive luminous paint continued to be used for some applications, and of course watches and other items such as alarm clocks and aircraft instruments manufactured in earlier times continued to be used. The picture here shows a warning in an Air Publication British military standard issued to the Navy and Royal Air Force in July 1966.
If your watch was made before 1960, and has thick paint, often even gungy looking in WW1 era watches, often yellowish brown on WW1 era and green on later watches, on the hands and numerals, and the hands and numerals are designed to carry a large area of paint rather than thin brush strokes, then the likelihood is that the original paint was made with radium, even if it no longer glows in the dark at all.
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Watch with radioactive luminous paint
Radium Luminous Paint
The half-life of radium is about 1,600 years, so over the 100 or so years since a watch dial was painted with luminous paint, the radium activity will have decayed about 4%, about 1% for every 25 years. This means that paint that was made with radium 100 years ago will still be 96% as radioactive today as the day it was made. Radium and its fission decay products (such as radon gas) have the potential to cause various health risks, and therefore watches with radium paint should be handled carefully and in ways to minimize these risks. The danger is not so much from radiation received from the watch when wearing or being near to it, but more from inhalation or ingestion of paint particles or contaminated dust.
Why doesn't old radium paint glow in the dark? You can't see radiation, and radium paint only glowed because the radioactive radium was mixed with a fluorescent compound, usually based on zinc sulphide. Radiation from the radium would hit the zinc sulphide, which would emit light in response. Over time the fluorescence property of the zinc sulphide was worn out by the radiation, and that is why the paint no longer glows in the dark. The radium is still there, almost as active as the day the paint was mixed, but the fluorescent compound no longer gives off light when it is hit by radiation.
There is also another problem. The radium and zinc sulphide were powdered and mixed with a binder such as clear varnish to make the paint. Over the years the radiation breaks down the molecular bonds in the varnish and it becomes weak and brittle. This is why old radium paint has often flaked off the hands and numerals of a watch dial. The flakes of paint can be as fine as dust, which can obviously be easily distributed about by accident, and even accidentally breathed in. If it was ordinary paint this wouldn't be much of a problem, but each flake of radium paint carries an amount of radioactive radium with it.
Radium and its decay products, the things it breaks down into (and the things that those things also break down into) emit alpha, beta and gamma rays. Alpha particles are composed of two neutrons and two protons, the same as the nucleus of a helium atom. This means that they are (relatively) large and slow moving, and have a positive charge. They can be stopped by a few inches of air or by the surface layers of your skin or, more importantly, the case or crystal of your watch. However, if flakes of radium paint are inhaled they can sit in the lungs, where the alpha radiation can hit the delicate (much more delicate than skin) internal tissue of the lungs and cause tumours. Beta particles are electrons which will also be stopped by the watch case or crystal. Gamma rays are electromagnetic radiation, like light or X-rays, but with higher energy. They will easily pass through the case of a watch.
There is no need to panic if you realise you have watch with radium paint. The watch that I describe testing with a radiation detector below is a 1918 World War 1 era watch, and whoever painted the luminous paint on the hands and dial seems to have applied a good thick coating, and the paint seems to have been particularly radioactive. I guess that at the time they just wanted a really good glow in the dark, and didn't appreciate the dangers. Later watches that I have tested since have much less paint on the hands and numerals, and are a lot less radioactive. I have a later watch from the 1920s, still in a Borgel case like the first one I tested, but the paint is a lot finer in application, rather than the big daubs on the first watch, and perhaps incorporates less radium - after all, it was an expensive substance. This second watch with the finer paint registers much lower on the radiation detector, and I wouldn't be anything like as concerned in wearing it.
Any watch with radium paint on the dial I regard as reasonably safe to wear on a once-in-a-while basis, and perhaps more regularly than that if the paint has been finely applied, unlike the watch pictured on this page. But to minimise risks it would still be sensible to not wear it all the time, and certainly don't sleep wearing it, or keep it on your bedside table. The much more significant danger occurs when opening or working on such a watch, and workers must be particularly careful not to breathe in any of the paint or its dust, or to spread bits of the paint around, contaminating the workspace.
Further information for persons working with watches that have this type of luminous paint is available on the HSE web site in the article NEW CONTROLS INTRODUCED ON TIMEPIECES CONTAINING RADIOACTIVE SUBSTANCES which you can get to by clicking on the link. This article states "Up until now those in the retail and antique trade have been free to dispose of damaged clocks and watches luminised with radioactive material, that are beyond repair, in the dustbin with other general refuse. Today because of a change in legislation made necessary by the Basic Safety Standards Directive (96/29/EURATOM) the situation has changed ... and you may be required, in certain circumstances, to seek Environment Agency approval under the Radioactive Substances Act 1993 (RSA 93) before disposing of such timepieces. Those circumstances are:
- if the timepiece is not made to international standards (which govern the use of radioactive substances at the time of manufacture); or
- if more than 5 timepieces, which meet international standards, are to be disposed of."
When watches were made with radium paint during the first half of the twentieth century there were no international standards governing the use of radioactive substances, these all seem to be modern (post 1950s) standards governing the use of tritium and promethium compounds. This would mean that all watches with radium paint fall into the first of the two categories listed and would need approval for disposal.
The article goes on to say "A major implication of this change in the law is that those in the retail and antique trade will now need to know what radioactive substances are on their premises and in what quantity." Although it is a "major implication", since this newsletter was published in 2002 there appears to have been no attempt to make anyone aware of the legislation, or any action taken to enforce it. I would say that the overwhelming majority of collectors, and those in the retail and antique trade, are totally unaware of this legislation.
The article finishes with a final clause "Please note this legislation does not apply to private individuals with a related horological hobby/collection."
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Testing Luminous Paint for Radioactivity
If you think your watch has luminous paint on the hands and numerals, the first easy test is to keep it in the dark overnight and examine it while still in the dark. Then expose it to sunlight and take it into a dark room. If it was dark after being kept in the dark overnight, and then charged up in the sunlight and glows brightly in the dark, it has a modern "light charged" luminous compound and is quite safe. Although zinc sulphide will charge up in sunlight and then glow in the dark, old radiation damaged zinc sulphide exhibits very little response to sunlight and its characteristics are very different to modern luminous paint. If the zinc sulphide doesn't glow in the dark due to radium radioactivity, but does glow when charged up by sunlight, then logic says there isn't any radium present.
However, if the paint remains dark at all times, then it may have radium paint. If it does glow faintly in the dark but doesn't charge up in sunlight, then it almost certainly has radium paint.
I bought a radiation detector so that I can test my own watches for radium based luminous paint. I am glad that I did - the first watch that I tried it on, the same black dial trench watch with plenty of luminous paint left on the dial, gave a strong reading as you can see below.
The first picture shows the radiation detector reading 0.14 micro sievert per hour background level, which is pretty normal, and the alarm level set by the factory at 0.3 micro sievert per hour (µSv/hr). The manual says that levels above 0.2 µSv/hr above background radiation need investigating and either clean up or evacuation, so with background at 0.14 µSv/hr the alarm level of 0.3 µSv/hr is just below the level at which action is required.
The second picture shows the effect of putting the watch next to the detector: the level jumps to 1.92 micro sievert per hour and the audible alarm goes beserk. In the manual accompanying the detector, it says ". . . if a dose rate of more than 1.20 micro sievert per hour is displayed, it is necessary to leave the zone urgently . . ." Although this warning refers to radiation levels which affect a whole area, rather than from a point source such as a watch where the intensity of the radiation experienced can be diminished by simply moving away from the watch, it does show that the amount of radiation given off by the watch is more than 10 times the naturally occurring background radiation and should not be simply ignored.
Pocket Geiger Smart Radiation Detectors
I bought my radiation detector some time ago and it was quite expensive. However, as a result of the nuclear accident at Fukushima, Japan, an organisation was set up to develop inexpensive radiation detectors for everyone. The resulting product is the Pocket Geiger Smart Radiation Detector, an accessory which is available for both IOS (iPhone, iPad etc.) and Android devices that works with a free downloadable app to display radiation readings on your smart device.
The Pocket Geiger is available in several different models and prices from around £40 from Radiation Watch UK. I haven't tried one of these myself yet so this is not a personal endorsement, but it looks like a handy and inexpensive piece of kit for anyone handling old watches with potentially radioactive paint, or even for anyone who is just interested to know how much radiation is in their surroundings. If you get one of these, do let me know how you get on with it.
Another Radioactive Watch
I didn't measure the radiation level of the watch above with the dial out of the case. However, here is another which I did test.
When it arrived it was in a zip lock bag, and the crystal was missing. I could see that the paint was the original radium paint so I decided to see what I was dealing with before I took it out of the bag. As you can see, I got a reading of over 5 µSv/hr. This rather surprised me because it was a lot higher than I had seen with the watch I described above, and this one seemed to have less paint remaining than that one. The higher reading may have been due to beta radiation that would have been stopped by the crystal but which could pass through the zip lock bag. I decided to remove the hands and dial, working on disposable paper towels and wearing a dust mask.
The next picture shows the dial and hands next to the radiation meter and, as you can see, it has gone off scale, so the radiation from the dial and hands is over 9.99 µSv/hr. I don't know how much over, because this is the maximum reading of the meter. As you can also see from this picture, there isn't much of the original radium paint left, just bits on the numbers from 12 to 4 and a bit on the 10 and the hour hand. That this small amount of paint produced so high a reading surprised me.
I then stripped the radium paint off the dial and hands and took some more readings. The dial then gave a reading of 1.47 µSv/hr so I guess I didn't quite get rid off all the paint.
I tested the movement after I had removed the dial, and also the case, before I did anything to them. I got a reading of 0.64 µSv/hr off the movement and 0.43 µSv/hr off the case.
Why were the movement and case showing a reading after I had removed the dial? It seems that one of the fission products of radium is radon gas, which can obviously move around inside the watch and, after a few days, itself fissions into solid materials. These are also radioactive and settle as dust on the watch movement and case. Obviously this dust is quite mobile so you need to be careful not to spread it around and contaminate your workspace.
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Radiation: What Do These "Sievert" Things Mean?
In the 1980s when I was working on building nuclear power stations I was a "Certified Radiation Worker" or some such thing, qualified for "hot temperature conditions", which meant that I was "allowed" to receive as part of my work an annual radiation dose of up to 5 rem, 20 times what was allowed for the general public to be exposed to. (In fact, I probably got more dose from the chest x-ray I had as part of my annual radiation worker's medical tests than I did in work.) I am used to talking in rems so the modern Sievert units leave me a bit in the dark, but I decided I needed to get up to speed and get familiar with the new units that my radiation detector uses, so here goes:
The impact of ionising radiation is measured as energy absorbed in body tissue in units of "gray". Exposure to different types of radiation does not produce equal biological effects, so when discussing radiation effects an equalising unit called a rem (Roentgen equivalent man), or now a Sievert (Sv) is used. Regardless of the type of radiation, one rem or sievert of radiation received produces the same biological effect. One sievert equals 100 rem, so my allowed exposure that used to be 5 rem per year would now be called 50 millisieverts per year (mSv/yr) (although I notice they have now reduced the allowed exposure for nuclear workers to 20 mSv/yr, or 2 rem/yr.)
In the UK, the legal limit for radiation exposure from sources such as nuclear plants for members of the public is 1 mSv a year. The "background radiation", the natural radiation that we are all exposed to is reckoned to be about 2 mSv per year, some of which comes from natural sources in the ground and in rocks, and some from cosmic radiation. Flying exposes you to more cosmic radiation and an airline crew flying the New York to Tokyo polar route are estimated to receive an annual exposure of 9 mSv per year because of this. A steady dose rate that gave an exposure of 1 mSv/yr would be about 0.1 micro sievert per hour (µSv/hr), 10 mSv/yr would be about 1 µSv/hr. The instruction manual which came with my radiation detector says that "defensive measures" (it's translated directly from Russian) should be employed if the measured radiation level in a room exceeds the external background level by 0.2 µSv/hr or more, which would correspond to 1.75 mSv/yr.
The background reading I measured away from the watch above of 0.14 µSv/hr would be 1.22 mSv/yr, which is below the usually quoted "typical"background radiation. The elevated level next to the watch of 1.92 micro sievert per hour works out at 16.8 mSv/yr, or about 10 times background radiation. This will all be gamma radiation escaping through the case or crystal of the watch. So this is the level of radiation someone wearing the watch would be exposed to. Obviously it's not "whole body" radiation, which the limits I discussed above are based on, but it is higher than I would want to be continuously exposed to.
I have now discussed this whole matter with the NRPB. The view of the person that I spoke to was that the dose of radiation that would be received from working on a watch like this for a short time was low enough to not be a concern. A dose rate of say 10 µSv/hr would take 100 hours to accumulate the 1 mSv allowed to members of the public from nuclear power plants, and 200 hours to equal background radiation. And this is not a whole body dose, which those figures are for. However, when working on a watch one is very close to it, and the eyes and fingers would be most exposed. Wearing an eyeglass or similar would protect the eyes from alpha and beta radiation, but would not stop the gamma.
The figure of 10 µSv/hr was rather plucked from the air because my radiation detector had gone off-scale at 9.99 µSv/hr. The issue of "Radiation Protection News" that I linked to above also has a section about vintage aircraft which notes that many aircraft built before circa 1950 have instrument dials luminised with radium paint. Dose rates on contact with these instruments can sometimes exceed 200 µSv/hr and dose rates in the pilot's position may be as high as 15 µSv/hr. The note goes on to give guidance that where dose rates in excess of 2.5 µSv/hr exist, steps should be taken to reduce radiation levels and/or prohibit access by members of the public. On the face of it, the radiation received from a watch would be broadly similar in extent to the radiation received from an aircraft instrument while sitting in the pilot's seat, and remember that 2.5 µSv/hr is less than I measured off the second watch while it was in its zip-lock bag.
The NRPB man was also concerned about removing the paint from the dial and hands, as this could be seen as creating "radioactive waste". The view seemed to be that as far as the authorities are concerned the paint is OK so long as it is on the dial inside the watch case, but that you shouldn't open the timepiece or remove the paint from the dial. The official view seems to be, it's OK to have one of these watches, but don't get too close to it, don't wear it, don't work on it, and don't remove the radioactive paint, but this doesn't apply if you are a private individual with a related horological hobby/collection.
So how do I deal with the residual activity on the case, movement and dial? I put the movement, dial and hands, and case, separately, in a bath of watch rinse solution in an ultrasonic tank to remove as much radioactive dust as possible. Usually this removes virtually all traces of radioactivity so that I feel safe to work on the watch as normal.
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What are the Dangers?
Although I have worked in the nuclear industry I don't have a qualification on the health effects of radiation, so these are just my thoughts based on my experience and on what I have picked up over the years.
We are all exposed to radiation all the time, natural radiation from cosmic rays, from radon gas escaping from the ground, etc.; and also to man made radiation from dental xrays, etc. etc. (there is no difference between natural and man made radiation, it's just that the source is different). The human body has evolved repair mechanisms for coping with the damage caused by natural levels radiation, or else we wouldn't be here, and these mechanisms can cope with levels of man made radiation that are similar in intensity to the natural radiation, but obviously if the intensity of the radiation is higher, then more damage can be caused than the repair mechanisms can cope with, and that is when health effects occur.
Little flakes of radium paint obviously aren't going to give you a radiation dose over your whole body, which is what the published medical effects are usually based on, but a flake of alpha emitting radium paint breathed in could potentially cause a tumour in your lungs; radium paint swallowed and digested is processed by the body similarly to calcium, and has been termed a "bone seeker" because it is selectively accumulated and retained in bones, which may cause long term effects. I don't know of any study into the actual health effects on watchmakers who have been working for years with radium paint, it may be not a lot because some old watchmakers say that they have restored or replaced the lume on hundreds of old watches and are not dead yet, but this is not a good reason to ignore the dangers.
All I can really say is that all nuclear radiation carries risks to human health, and as radium gives off nuclear radiation, radium paint is a health risk. However, in the context of watches, the question must be just how dangerous is the small quantity of radiation contained in the radium paint.
When I worked in the nuclear nuclear power industry the safety culture was that radiation doses to the general public should not only be low, i.e. well below the level at which health effects were known to occur, they should be be ALARP - As Low As Reasonably Practical. The reasoning behind this is that exposure to nuclear radiation can, but doesn't necessarily, cause cancer. The higher the dose of radiation, the greater is the risk. Small doses of radiation carry only a small risk, but governments who have the health of millions of people to worry about get concerned about small risks because a small risk times millions of people will result in some positive outcomes, that is why members of the public are not allowed into the cockpits of old aeroplanes if the instruments have radium paint on them, because it is a small but easily avoidable risk.
So the question is, should you avoid old watches with radium paint on them, because of the risk to your health from the radiation? This is something only you can decide, and depends on your attitude to risk.
Just wearing a watch with radium paint means that you get a dose of gamma radiation, most intensely to your wrist, but also all over your body. The dose is not high enough that you will see any immediate health effects such as reddening of the skin, but it adds to the dose that you get from cosmic radiation, natural background radiation, medical x-rays, etc. The dose will be small, especially if you don't wear the watch very often, and is probably small enough that the risk will be very low, smaller than the risk from cosmic radiation, natural background radiation, medical x-rays, etc., and probably very much smaller than the risk you get from driving to work each day. So I personally don't worry too much about it, but I am always aware that it is there.
However, working on watches with radium paint presents an entirely different level of risk. It obviously opens the possibility of doses of alpha and beta radiation simply because the paint is no longer behind the crystal. There is also the danger from loose flakes of the old paint that can fall off at any time. If you do not take precautions, such as wearing a mask, you might breath in or swallow flakes of radium paint, and then you would have radioactive material inside your body, which is something to be avoided.
So my bottom line is that wearing an old watch with radium paint may involve a small health risk, but that risk is probably very low and smaller than other risks that I am exposed to in everyday life such as driving a car or regularly eating red meat. I am comfortable with that level of risk and continue with my hobby, but I am always aware that an old watch might carry radium paint and I am aware of the dangers. If you are not comfortable with risk, or want to do everything you can to minimise yours, then you might want to avoid old watches - and maybe driving to work, eating red meat, etc. etc. However, if I work on an old watch, I am aware that the dangers are much greater and I take the precautions I have outlined elsewhere on this page.
I have recently found a paper "Radium Timepiece Dose Modeling" prepared for the U.S. Nuclear Regulatory Commission. This looks as if it has some useful information in it, which I will try to summarise here in due course. In the meantime, the paper is available on the internet if you wish to read it yourself.
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The Bottom Line
So what's my final position on all of this, I hear you asking. Well, as a private individual with a horological hobby and collection, the rules laid down by the Environment Agency don't apply to me. However, I am conscious that I don't want to take any unnecessary risks with my own health, so I am going to be careful when working on watches luminised with radioactive paint and take the precautions outlined in the "And Finally" section below, and I am not happy about simply sending in any form old luminous material to landfill, so I am going to work with on that too - although I am not quite sure how at the moment. The BHI would appear to be the obvious first place, so I have contacted them.
It doesn't take long to remove the dial from a watch and strip the paint off, and clean the case and movement, so my annual exposure to gamma and beta radiation from this source will be low, and I will try to avoid inhaling or ingesting any radioactive materials by using a mask. I will take the steps I have outlined to keep my workspace free of contamination and I will monitor the levels of radioactivity with my geiger counter.
I will dispose of the residual paint, mask, gloves etc. in the bin, on the basis that this is only the same quantity of material as an unknowing member of the public putting a complete watch in the bin. I am not happy about this and would much rather send the paint to a safe disposal rather than landfill, but the "powers that be" have made the process so costly and complex that this is not possible for me.
If you have any questions or comments, please don't hesitate to contact me via my Contact me page.
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Repainting Luminous Dials - Some Notes of (aesthetic) Caution
I decided to get the dial of this watch repainted to remove the radium paint. Although I think it is fair to get a dial repainted on a run-of-the-mill watch that you want to wear everyday, historically significant watches should as far as possible be preserved if they are in good condition; but of course most watches fall somewhere in between run-of-the-mill and historically significant. For instance I have one of the first officially issued British military wristwatches from 1917 which I wouldn't even think of having repainted because of its historic importance, but other watches I wouldn't be so bothered about if say a lot of the (brittle) radium paint was already missing. Did you know that at one time the RAF stopped using luminous watch dials because the vibration of the aircraft shook the radium paint off?
Before I wrote this web page I had had an Omega dial restored because most of the radium paint had been lost, and the dial painter has done a very good job in reproducing the thick appearance of the old radium paint, which considerably improved the appearance of the dial and the watch now looks very good. But the watch that is pictured on this page was restored by another company, and they have replaced the old paint with modern luminous light charged paint. I don't have a problem with the use of modern luminous paint, but they haven't reproduced the colour and appearance of the old paint and this has rather spoiled the vintage appearance of the watch. This has caused me to be more cautious in having dials restored.
Modern luminous paint could be considered to be out of place on a WW1 era watch, because it charges up in sunlight and then glows brightly in the dark, shouting out that the worn out radium paint has been replaced with a modern luminous paint. A more accurate restoration would be to use non-luminous paint, because no original WW1 era watch glows in the dark today. But there are good reasons for replacing radioactive paint with modern luminous paint. The old paint is radioactive and so there are good health reasons for replacing it. This should be done carefully, reproducing the colour and texture of the old paint so that the watch retains its vintage appearance. However, if this is done skilfully using a non-luminous paint, how is someone to tell if the watch has new paint instead of old radioactive paint? Not everyone wants to invest in a radiation detector, so using a modern luminous paint, with its distinctive characteristic of charging up in sunlight and then decaying in brightness in the dark, is a good way to show that the paint has been changed and is safe. And it will also glow in the dark, an effect which everyone likes!
Bear in mind that removing the paint is easy, putting it back to match the original is difficult. I would recommend that you take some close up pictures of the dial and hands and send them to several companies. Give a detailed description of what you want doing and ask them if they can do it in the way that you wish. If you want the dial and hands to look exactly like they do now, paint colour and finish included, make sure you say so. Be as detailed as you can in describing what you want, don't imagine that they will know. Take up references and do your due diligence before committing your dial to them.
I have used a couple of UK based dial repainters, but they tend to be quite expensive. US dial refinishers seem to be cheaper because they have a greater market and therefore are able to work on a larger scale, more commercial basis. A poll on the NAWCC message boards recommended a number of US dial refinishers, with International Dial Co. coming out as the clear winner. Next time I need a dial refinishing I am going to give them a try, and I will record the outcome here. NB: I haven't used International Dial Co. yet, and I don't have any connection with the company, so this is not a personal recommendation from me, I am just going on the results of the NAWCC poll.
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If you insist on removing radium paint yourself, then be very careful. I can't give you any "guidelines" for obvious reasons, but here is what I would do, just for your information. These are not recommendations, just notes of what I do - I can't and don't take any responsibility for what you do.
When dealing with an old watch with what looks like luminous paint I am always aware that there may be loose flakes of paint under the crystal on the dial, and radioactive dust from radon decay throughout the movement: before I opened the watch, or even the packaging that it was delivered in, I think about how I am going to deal with these. I would wear a disposable dust mask and disposable latex gloves and work on disposable paper towels, and try to work quickly to minimise my exposure, but without rushing.
To strip the paint from the dial and hands I would probably use a liquid paint stripper and make sure that the dial and hands remain submerged or covered by the liquid while flaking stubborn bits of paint off - the idea being to avoid any dust or tiny flakes of paint becoming airborne. I would probably then wash the movement and case in a bath in an ultrasonic cleaner to remove radioactive radon decay dust before dismantling the movement.
After I had finished working I would dispose of the mask, gloves and the paper towels. I would fold them up carefully so that anything on them is contained. I would then give the work surface where I was working a good wipe down with a disposable damp cleaning cloth and dispose of that too. And then check everything with my Geiger counter.
How to dispose of the now-radioactive paint stripper and liquid the movement and case was cleaned with is then a concern. I am fairly sure that pouring them down the drain is a not a good idea, but I believe that the quantity of radioactive material from single watch is acceptable to put in the bin for landfill disposal - after all, this is only the same quantity of material as an unknowing member of the public putting a complete watch in the bin. As I said before, I am not happy about this and would rather it was disposed of properly - or even reused, I am sure that radium must still have its uses - but it appears I have no choice other than to put it in the bin.
Let me know if you have any better ideas - legal ones, that is! And remember, these are not my recommendations, they are just thoughts to help you decide what to do - anything you actually do is your own responsibility.