# Can semen stains glow under black light ? **URL:** \ **Category:** Factual Questions\ **Created:** [May 23, 2012, 9:05pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878 "2012-05-23T21:05:13Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![nofancies](https://avatars.discourse-cdn.com/v4/letter/n/ed655f/32.png) [@nofancies](https://boards.straightdope.com/u/nofancies)\ **Post date:** [May 23, 2012, 9:05pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/1 "2012-05-23T21:05:13Z")
Hi all, Can anyone tell me if semen stains would definitely glow under a black light (UV light) ? I’ve been told that they would glow in greenish-yellow under the UV light. But later on someone said semen stains cannot glow without a substance called ‘luminol’. Which one is true??? And if the semen stains were stuck on a bed sheet like 5 months ago,(being slept on but never been washed), is it possible that the semen substances still remain on it? Would the scrubbing or fiction makes them totally coming off or disappear? Thanks in advance! ---
**Author:** ![JohnT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnt/32/15048_2.png) [@JohnT](https://boards.straightdope.com/u/JohnT)\ **Post date:** [May 23, 2012, 9:08pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/2 "2012-05-23T21:08:27Z")
Need answer fast! ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [May 23, 2012, 9:11pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/3 "2012-05-23T21:11:36Z")
[This thread on a different board](http://forensicsncrime.proboards.com/index.cgi?board=forensicquestions&action=display&thread=383) starts from the given that semen will fluoresce under black light, and I don’t see anyone contradicting that. ---
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [May 23, 2012, 9:12pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/4 "2012-05-23T21:12:56Z")
[Luminol](http://en.wikipedia.org/wiki/Luminol)reacts to iron found in blood. Not sure it would work with semen… ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [May 23, 2012, 9:16pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/5 "2012-05-23T21:16:00Z")
Luminol is for making blood glow, not semen. Semen will glow on it’s own under a black light. Blood does not glow under black light. However, when luminol reacts with the iron in the blood, it glows. ---
**Author:** ![awldune](https://avatars.discourse-cdn.com/v4/letter/a/c77e96/32.png) [@awldune](https://boards.straightdope.com/u/awldune)\ **Post date:** [May 23, 2012, 9:29pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/6 "2012-05-23T21:29:52Z")
Are we talking about a proper forensic black light, or a black light bulb like you can buy at the supermarket? I have tested with the latter and it didn’t work. ---
**Author:** ![nofancies](https://avatars.discourse-cdn.com/v4/letter/n/ed655f/32.png) [@nofancies](https://boards.straightdope.com/u/nofancies)\ **Post date:** [May 23, 2012, 9:38pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/7 "2012-05-23T21:38:25Z")
Hi awldune, is a black light i bought on amazon…I guess that’s the supermarket standard. What’s your outcomes? I have put that stain (on the bed sheet) right on the black light and it appears as yellow. It looks transparent under normal lights… ---
**Author:** ![VinylTurnip](https://avatars.discourse-cdn.com/v4/letter/v/b2d939/32.png) [@VinylTurnip](https://boards.straightdope.com/u/VinylTurnip)\ **Post date:** [May 23, 2012, 9:41pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/8 "2012-05-23T21:41:34Z")
I’m curious where all of you experimenters are getting your sample mater… _ohhh_. Right. ---
**Author:** ![JohnT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnt/32/15048_2.png) [@JohnT](https://boards.straightdope.com/u/JohnT)\ **Post date:** [May 23, 2012, 9:54pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/9 "2012-05-23T21:54:07Z")
This badly-recorded [clip from The Office](http://www.youtube.com/watch?v=aKCS49wfdpE) is the first thing I thought of when I read the thread title. Perhaps the OP is Dwight Schrute? 😉 ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [May 23, 2012, 9:55pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/10 "2012-05-23T21:55:23Z")
> [@JohnT](#): > > This badly-recorded [clip from The Office](http://www.youtube.com/watch?v=aKCS49wfdpE) is the first thing I thought of when I read the thread title. > > Perhaps the OP is Dwight Schrute? 😉 Funny, I thought of Ming-Na from _ER_. ---
**Author:** ![nofancies](https://avatars.discourse-cdn.com/v4/letter/n/ed655f/32.png) [@nofancies](https://boards.straightdope.com/u/nofancies)\ **Post date:** [May 23, 2012, 9:57pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/11 "2012-05-23T21:57:45Z")
funny clip. 😛 JohnT. So now the question becomes: How do semen stains look like after scrubbing off? Would it be transparent? If it is still visible, does it mean it can be tested out? ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [May 23, 2012, 10:09pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/12 "2012-05-23T22:09:20Z")
> [@JohnT](#): > > This badly-recorded [clip from The Office](http://www.youtube.com/watch?v=aKCS49wfdpE) is the first thing I thought of when I read the thread title. I thought of [this one](http://www.youtube.com/watch?v=HRo_6nMs9xU). ---
**Author:** ![drewtwo99](https://avatars.discourse-cdn.com/v4/letter/d/d07c76/32.png) [@drewtwo99](https://boards.straightdope.com/u/drewtwo99)\ **Post date:** [May 23, 2012, 10:20pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/13 "2012-05-23T22:20:11Z")
5 months without washing the sheets. Now THAT’S class! ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [May 23, 2012, 10:21pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/14 "2012-05-23T22:21:59Z")
> [@drewtwo99](#): > > 5 months without washing the sheets. Now THAT’S class! Without washing the \*spunky \*sheets, no less. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [May 24, 2012, 12:44am UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/15 "2012-05-24T00:44:52Z")
> [@nofancies](#): > > So now the question becomes: How do semen stains look like after scrubbing off? Would it be transparent? If it is still visible, does it mean it can be tested out? Am I the only one who read this as TASTED out? ---
**Author:** ![crypto](https://avatars.discourse-cdn.com/v4/letter/c/b3f665/32.png) [@crypto](https://boards.straightdope.com/u/crypto)\ **Post date:** [May 24, 2012, 1:18am UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/16 "2012-05-24T01:18:45Z")
> [@drewtwo99](#): > > 5 months without washing the sheets. Now THAT’S class! My freshman year roommate went longer than that. Needless to say, he wasn’t my soph year roommate. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [May 24, 2012, 2:30am UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/17 "2012-05-24T02:30:13Z")
> [@awldune](#): > > Are we talking about a proper forensic black light, or a black light bulb like you can buy at the supermarket? I have tested with the latter and it didn’t work. Me too. Mine was one of those invisible ink pens, and I suspect the light was more blue than UV. Maybe not much high energy UV. ---
**Author:** ![nofancies](https://avatars.discourse-cdn.com/v4/letter/n/ed655f/32.png) [@nofancies](https://boards.straightdope.com/u/nofancies)\ **Post date:** [May 24, 2012, 6:28pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/18 "2012-05-24T18:28:52Z")
I put the uv light very close to the bed sheet, and saw some yellow colour on it. I guess if the room is dark enough and u put the light very close, it works. ---
**Author:** ![Ambivalid](https://avatars.discourse-cdn.com/v4/letter/a/a5b964/32.png) [@Ambivalid](https://boards.straightdope.com/u/Ambivalid)\ **Post date:** [May 24, 2012, 6:38pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/19 "2012-05-24T18:38:33Z")
> [@nofancies](#): > > And if the semen stains were stuck on a bed sheet like 5 months ago,(being slept on but **never been washed** ) (bolding mine) Something tells me that semen was ‘summoned’ in a solo mission. ☹ ---
**Author:** ![Darth\_Panda](https://avatars.discourse-cdn.com/v4/letter/d/ee7513/32.png) [@Darth\_Panda](https://boards.straightdope.com/u/Darth_Panda)\ **Post date:** [May 24, 2012, 6:43pm UTC](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878/20 "2012-05-24T18:43:27Z")
> [@nofancies](#): > > How do semen stains look like after scrubbing off? You spelled rubbing off wrong. [Next page](https://boards.straightdope.com/t/can-semen-stains-glow-under-black-light/622878.md?page=2)