Mkiii Prismatic Compass Question

Hi everyone, first post here so hope I've done everything right.

A few months back I rather gladly came into possetion of this lovely compass

https://www.milsurps.com/images/impo...4cce3174-1.jpg

https://www.milsurps.com/images/impo...a3d094b0-1.jpg

https://www.milsurps.com/images/impo...423eaef1-1.jpg

And it is to my very limited understanding that these were manufactured with radium lume in several areas. As you could imagine this made my family a little paranoid and it has regretfully been relegated to the shed.

I've done a little research and it seems the compass has at some point in the past been refurbished, if a little crudely (especially the markings on the base)

Now could anyone tell me if the lume currently applied is indeed radium?

https://www.milsurps.com/images/impo...dca3db83-1.jpg

https://www.milsurps.com/images/impo...e9967a3c-1.jpg

https://www.milsurps.com/images/impo...b3e12eb4-1.jpg


From what I've learned the little brown blob on the inside of the rotating bezel is almost certainly radium. It does not glow under its own power or by charging with light. The rest of the marking DO glow for about 45 minutes from being charged by a flashlight but DO NOT glow under their own power.

I know this is probably an exceptionally dumb question to those in the know, but id really rather be safe than sorry.

Thanks.

Welcome to the forum...there are several men here that have serviced these professionally and they'll be along. I was the user and I can tell you there's nothing to worry about with these. I have children, grandchildren and can still function normally. The illuminates contained are of no danger to you...you'd need to drink a firepail full. Then you'd be sick...

Well thats good to know at least, I wasn't planning on sprinkling it on my cornflakes anyhow hehe.

Just as BAR (thread 2) says above, I'm one who has stripped these down to the bare bones and rebuilt many hundreds of them to a Base Workshop standard during the 60's and 70's. They are indeed radium illuminated and are as tough as old boots. You are being a tad, er............ 'sensitive' keeping it in the shed if I might be so diplomatic as to say so. Just keep it safe in a drawer at home and feel free to teach your kids to map read with it instead of the far less accurate Silva compass. I taught my son many years ago and gave him one to keep afterwards.

Don't worry about the awful engraving on the base of the case. It's the accuracy of the insides that is all you need to concern yourself with. Is that at bubble I see inside it? If so, it's 'gassed' and is now inaccurate and pretty well useless if it is.

Thanks for taking the time to look at it a bit for me, and no it isn't a bubble just a trick of the light.

So would you say theres any chance at all that when it was repainted, that the card and case were relumed with regular old phosphorescent paste? Just because from what I could learn online, radium no longer glows at all and turns a horrid rust colour. Is that something that would be done if it were still in use untill recently?

I know getting it out of the house was probably an overreaction, it's just that the I read the dust is rather harmful so I panicked a bit.

Cheers.

I would imagine that when/if it were refurbished in the 50's or 60's that the old illum would have been carefully scraped, just a key left and re-painted. Just as it had always been done. Until about 1969 or so when things changed. I don't recall seeing any where the illum had turned a rusty colour. It just failed and that was that!

As for the dust being harmfull..... We scraped/keyed them before they were repainted. No masks and just swept our work benches down every few days or so without a second thought! Same as Wristwatch dials and...... In fact my old Army Omega wrist watch still causes the dozymeter to sing like a canary whenever I walk past!. In the 50's my dad had a small tin of radium paint that he used on his fishing floats that he also dobbed on the headlights of all my Dinky Toy headlights. And there they sat for years and years, glowing like Christmas trees parked on my window sill!

I'd just use it, teach your kids proper map reading but as BAR suggests above, do try not to drink the isoprophyl alcohol damping fluid if you can help it!

Quote:

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Originally Posted by Peter Laidler

o try not to drink the isoprophyl alcohol damping fluid if you can help it!

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That's a different story...

Okay then, thanks kindly for that.

Just out of curiosity then, what process would've been used post 1969? Or were these not permitted to be issued after then.

I think the tritium stick-on light sources came on stream. Thereafter any dials etc that had lost their illum were put into a drum and 'disposed of' instead of the usual pre '69 method of throwing them in the bin.