# What colour does radium fluoresce? **URL:** \ **Category:** Factual Questions\ **Created:** [September 17, 2005, 3:12am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083 "2005-09-17T03:12:27Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![FlyingRamenMonster](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@FlyingRamenMonster](https://boards.straightdope.com/u/FlyingRamenMonster)\ **Post date:** [September 17, 2005, 3:12am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/1 "2005-09-17T03:12:27Z")
I need to know what colour radium glows in the dark. I have consulted many sources (the internet, my chemistry textbooks…). All of them say that radium fluoresces. None of them say what _colour_ it fluoresces at. Wikipedia says it’s blue but all the pictures I’ve found of luminous clock dials and the like are green. I seem to recall a biography of Marie Curie I read a few years back describing it as pale blue but I can’t find the book anymore. Argh, what colour is it? ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [September 17, 2005, 3:22am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/2 "2005-09-17T03:22:42Z")
There’s a joke here about Curie dying of radiation poisoning, but I won’t make it. I’ll just post because I’m also curious and want to know. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [September 17, 2005, 3:30am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/3 "2005-09-17T03:30:27Z")
I don’t know the specific answer to your question, but the green glow you see on modern watch and clock hands and dials is not radium. Radium has not been used for this purpose since the late 60s. Modern watches and clocks use a either a non-toxic phosphorescent paint, or a tritium-containing fluorescent paint. Tritium is still radioactive, but as a weak beta-emitter, it’s considerably safer than radium. ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [September 17, 2005, 3:44am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/4 "2005-09-17T03:44:02Z")
Pure radium has a faint blue glow. When mixed with zinc sulphide they glow with a brighter green color; that is what was used as luminescent paint. [http://www.orau.org/ptp/collection/radioluminescent/radioluminescentinfo.htm](http://www.orau.org/ptp/collection/radioluminescent/radioluminescentinfo.htm) ---
**Author:** ![FlyingRamenMonster](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@FlyingRamenMonster](https://boards.straightdope.com/u/FlyingRamenMonster)\ **Post date:** [September 17, 2005, 3:45am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/5 "2005-09-17T03:45:22Z")
I was talking about the pictures of wartime clocks I found on Google, actually, but I’m not sure if it’s just the _paint_ that was green or if they actually glowed green too, since I don’t think any of them actually glow anymore. Hum. ---
**Author:** ![FlyingRamenMonster](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@FlyingRamenMonster](https://boards.straightdope.com/u/FlyingRamenMonster)\ **Post date:** [September 17, 2005, 3:47am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/6 "2005-09-17T03:47:09Z")
Argh. And the prize for most instances of “actually” in a sentence goes to… ---
**Author:** ![FlyingRamenMonster](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@FlyingRamenMonster](https://boards.straightdope.com/u/FlyingRamenMonster)\ **Post date:** [September 17, 2005, 4:39am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/7 "2005-09-17T04:39:16Z")
Wait, did I say “fluoresce”? I meant “luminesce”. :smack: Way to look intelligent, C#M. ---
**Author:** ![katesisco](https://avatars.discourse-cdn.com/v4/letter/k/2bfe46/32.png) [@katesisco](https://boards.straightdope.com/u/katesisco)\ **Post date:** [May 30, 2012, 8:50pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/8 "2012-05-30T20:50:45Z")
I just moved into a high rise apr and discovered my shower drain glows blue; there is no natural light. I am wondering if this is due to the previous tenant undergoing some form of radiation therapy such as thyroid treatment. If this radioactivity is due to this or something like it, what is needed to protect the next tenant? ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [May 30, 2012, 8:55pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/9 "2012-05-30T20:55:55Z")
> [@katesisco](#): > > I just moved into a high rise apr and discovered my shower drain glows blue; there is no natural light. I am wondering if this is due to the previous tenant undergoing some form of radiation therapy such as thyroid treatment. If this radioactivity is due to this or something like it, what is needed to protect the next tenant? Even if the previous tenant peed non-stop in the shower after receiving thyroid radiation treatment (with pee being the only significant source of radiation post “thyroid radiotherapy”), the radiation would come from I[sup]131[/sup] which doesn’t glow, in any color. ETA: After several days, the residual radiation after thyroid I[sup]131[/sup] treatment is negligible in any case. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 30, 2012, 9:06pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/10 "2012-05-30T21:06:03Z")
> [@katesisco](#): > > I just moved into a high rise apr and discovered my shower drain glows blue; there is no natural light. I am wondering if this is due to the previous tenant undergoing some form of radiation therapy such as thyroid treatment. If this radioactivity is due to this or something like it, what is needed to protect the next tenant? Does it glow blue all the time, or only during the day? ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [May 30, 2012, 9:08pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/11 "2012-05-30T21:08:48Z")
> [@katesisco](#): > > I just moved into a high rise apr and discovered my shower drain glows blue; there is no natural light. I am wondering if this is due to the previous tenant undergoing some form of radiation therapy such as thyroid treatment. If this radioactivity is due to this or something like it, what is needed to protect the next tenant? [Ringworm](http://aristhu03.wordpress.com/2011/03/11/217/)? Eeeewwwww!!! ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [May 31, 2012, 1:46pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/12 "2012-05-31T13:46:59Z")
Sorta tangential, but as a child, I wanted to be a geologist. When I was 12 years old, my parents gave me a “rock collection” kit for Christmas. Included in it was a chunk of uranium ore (carnotite)-which also contains small amounts of radium. I had the rocks on a shelf in my bedroom, and I noticed that after the lights were turned out (and my eyes adjusted to the darkness), the carnotite piece would exhibit a faint blue glow…was I being poisoned?☹ ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [May 31, 2012, 10:08pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/13 "2012-05-31T22:08:42Z")
> [@ralph124c](#): > > Sorta tangential, but as a child, I wanted to be a geologist. When I was 12 years old, my parents gave me a “rock collection” kit for Christmas. Included in it was a chunk of uranium ore (carnotite)-which also contains small amounts of radium. I had the rocks on a shelf in my bedroom, and I noticed that after the lights were turned out (and my eyes adjusted to the darkness), the carnotite piece would exhibit a faint blue glow..was I being poisoned?☹ Yes. You will probably die within the next 7 decades. ---
**Author:** ![Lasciel](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lasciel](https://boards.straightdope.com/u/Lasciel)\ **Post date:** [May 31, 2012, 10:20pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/14 "2012-05-31T22:20:32Z")
Damnable zombie threads. And here I was all excited because I knew that radium-painted watches were only bright green because of the zinc sulphide. Only 7 years too late to be of service. Fun trivia fact: the girls who painted the watches with radium were told to use their lips to shape the bristles of the brushes, as their saliva would help make the tips stiffer, and therefore more precise in painting the dials and markings. After a while at work, their hair and nails would glow faint blue-green in the dark, making them very popular at parties. :eek: ---
**Author:** ![wheresmymind](https://avatars.discourse-cdn.com/v4/letter/w/91b2a8/32.png) [@wheresmymind](https://boards.straightdope.com/u/wheresmymind)\ **Post date:** [June 1, 2012, 4:17am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/15 "2012-06-01T04:17:33Z")
> [@Lasciel](#): > > Fun trivia fact: the girls who painted the watches with radium were told to use their lips to shape the bristles of the brushes, as their saliva would help make the tips stiffer, and therefore more precise in painting the dials and markings. After a while at work, their hair and nails would glow faint blue-green in the dark, making them very popular at parties. :eek: Not so fun fact: many of [these girls](http://en.wikipedia.org/wiki/Radium_Girls) died of radiation poisoning, or were disfigured when their [jaw bones rotted away](http://en.wikipedia.org/wiki/Radium_jaw). A group of them sued the company and won, establishing the right for workers in the US to sue their employers for damages from occupational illness. ---
**Author:** ![Ionizer](https://avatars.discourse-cdn.com/v4/letter/i/5daacb/32.png) [@Ionizer](https://boards.straightdope.com/u/Ionizer)\ **Post date:** [June 1, 2012, 11:17am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/16 "2012-06-01T11:17:31Z")
> [@KarlGauss](#): > > Even if the previous tenant peed non-stop in the shower after receiving thyroid radiation treatment (with pee being the only significant source of radiation post “thyroid radiotherapy”), the radiation would come from I[sup]131[/sup] which doesn’t glow, in any color. > > ETA: After several days, the residual radiation after thyroid I[sup]131[/sup] treatment is negligible in any case. Nitpick: I-131 has half-life of ~8 days. I used to dole out ‘treatment/ablation doses’ being a Nuclear Med Tech, and it was standard to tell patients that they needed be attentive to their wastes (and proximity-time of others to their ‘hot’ thyroid gland, like holding babies or spouse snuggling close while asleep, etc) for about a month or so max (less with smallish doses). Maximum dosing for outpatients was (is?) below 30 mCi - higher required hospitalization and special handling of body fluids/wastes until levels dropped (per NRC regs). We did not do in-patient dosing levels. This was during the '90’s, too, so things may be different now. From [here](http://www.radiologyinfo.org/en/info.cfm?pg=radioiodine): Radiation detection devices used at airports and federal buildings may be sensitive to the radiation levels present in patients up to three months following treatment with I-131. Depending on the amount of radioactivity administered during your treatment, your endocrinologist or radiation safety officer may recommend continued precautions for up to several weeks after treatment. ETA: no glowing or such could occur from I-131, though MANY patients asked if the stuff caused anything as such. I fought their ignorance best I could 🙂 ---
**Author:** ![terentii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terentii/32/212_2.png) [@terentii](https://boards.straightdope.com/u/terentii)\ **Post date:** [June 3, 2012, 10:55am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/17 "2012-06-03T10:55:06Z")
> [@katesisco](#): > > I just moved into a high rise apr and discovered my shower drain glows blue; there is no natural light. Maybe your region just has really hard water, and it contains amounts of light-emitting minerals/elements? Is this even possible? 😕 ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [June 3, 2012, 11:36am UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/18 "2012-06-03T11:36:42Z")
> [@](#): > > What colour does radium fluoresce? “Need answer fast”? If so, you got problems… ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [June 3, 2012, 12:47pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/19 "2012-06-03T12:47:40Z")
Is it not the yellow/green color of watch dials and [old aircraft instruments?](http://www.youtube.com/watch?v=7a4nL0cylgs) ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [June 3, 2012, 1:06pm UTC](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083/20 "2012-06-03T13:06:18Z")
> [@carnivorousplant](#): > > Is it not the yellow/green color of watch dials and [old aircraft instruments?](http://www.youtube.com/watch?v=7a4nL0cylgs) No, that’s the Zinc Sulphide glowing, excited by the Radium. According to Wikipedia, [Radium](http://en.wikipedia.org/wiki/Radium) glows a faint blue. [Next page](https://boards.straightdope.com/t/what-colour-does-radium-fluoresce/322083.md?page=2)