Max Kohl AG March Compass & Radium

[rhys1]

I’ve recently picked up a Max Kohl HAB marked march compass. It’s a beautiful item and I picked it up to accompany my map case and maps display.





On conducting a little further research (post purchase unfortunately!) I’ve discovered that the luminescent paint is radium based. Owing to the half life of radium being some 1600 years (!) I’m now a little concerned about owning an actively radioactive item. A recent paper has also discovered that as the radium breaks down it can also produce radon gas. The radiation from the radium that’s under the glass should mostly be ‘contained’ but I’m concerned about the sighting line in the lid.

Does this issue concern anyone here ?

[Fsoq]

Very nice ! I love it. Now, you have to find the rare lanyard

[Uncle Goose]

You don't have to worry, as long as the Radium is contained it's not really harmful. The radiation it emits doesn't travel very far (a few cm at best). Radium only becomes a problem is it gets free and can float around in the form of dust and very fine particles because then it can be inhaled or ingested. But as long it's not flaking off and you keep the compass closed it can go nowhere. The amount of Radon gas it can emit is extremely small, Radon is also found in nature so you inhale more Radon in a day then this will emit in years.

I collect NBC gear btw so I know what I'm talking about. I have a few Radium sources that are encased in plexiglass that I use to test detection equipment with.

[rhys1]

You don't have to worry, as long as the Radium is contained it's not really harmful. The radiation it emits doesn't travel very far (a few cm at best). Radium only becomes a problem is it gets free and can float around in the form of dust and very fine particles because then it can be inhaled or ingested. But as long it's not flaking off and you keep the compass closed it can go nowhere. The amount of Radon gas it can emit is extremely small, Radon is also found in nature so you inhale more Radon in a day then this will emit in years.

I collect NBC gear btw so I know what I'm talking about. I have a few Radium sources that are encased in plexiglass that I use to test detection equipment with.

Thank you for your reassuring response, from a risk management perspective, I’d like to keep the item but am looking for a watch / compass repairer to remove all traces of the radium and replace it with non radioactive paint. I don’t think this will detract from the item as the radium fades to brown as opposed to the original colour a ‘greeny white’.

Has anyone had this done / Is anyone able to recommend someone who can ?

[Uncle Goose]

I'm not sure anyone is willing to undertake such a thing, it's one thing to handle Radium but it's another to start removing it from objects. Most qualified watchmakers are very aware of Radium in dials and I doubt they are willing to start removing it. Even such small quantities require special handling procedures that are most likely out of the scope of any watchmaker. I would leave it like that, certainly because it's doing no harm and it's not that this is an item you have to handle or use daily.

[rhys1]

I’m in the process of trying to find a watch / compass repairer to remove the radium paint fro the compass and replace it with white paint (which is how it would have looked from the factory). This I’m hoping will remove any risks from the item.

Here are two links that those who collect compasses / gauges might like to read :-

https://www.hodinkee.com/articles/ne...serious-danger

Recent UK University research paper regarding Radon gas emission from watches with radium markings :-

https://www.northampton.ac.uk/news/w...s-cancer-risk/