Do UV-brighteners included in detergents make you glow in UV-Vision?
This is rather a hunting camo topic but interesting for military adaption as well!
Lately I've been reading through nearly everything that is written about: "washing your camouflage with detergents containing uv-brighteners makes you glow like a christmas tree to deer that can see in the ultra-violet spectrum".
I believe that the scientific tests indeed strongly indicate that deer see blue and uv light and in the yellow spectrum. Red and green shall appear to them as shades of gray like to humans with dicromatic sight.
The uv vision is extremely useful for animals to find food and to uncover potential enemies/predators. Latter works as following: In a snow covered arctic region a white furred polar bear is spotted in the white snow because it doesn't reflect the uv light as much as the snow does. (http://www.sciencecodex.com/reindeer...raviolet_light)
In an other example you have forest in the summer with a lot of grren plants. The chlorophyll in the plants absorb the uv nearly completely. So everything else hiding in the green must appear brighter (yes, also a hunter in the best colour maching
The strongest natural uv radiation you got in the bright sunlight. Of course at that time of the day all the other coulours are best seen. At dusk/dawn the light becomes weaker and changes the spectrum towards the uv spectrum. So at that time of day (most interesting time for hunting) the deer should see (moving) things with a uv reflection different from the background quite well.
Now back to the detergents and the blue glow if hit by artificial uv light. The UV-brighteners work as following:
"Fluorescent whitening agents (FWAs) are chemicals added to most fabrics and papers during manufacture to increase color
temperature, "whiteness," and "brightness." FWAs accomplish this by absorbing energy in the ultraviolet (UV) part of the
spectrum and emitting it as visible blue light.
Recently, hunters have become concerned that FWA could be reducing the
effectiveness of their camouflage clothing. As a result, some manufacturers have begun making their camouflage clothing (camo)
without FWA, and a spray-on product has been introduced to block the action of FWA. Radiometric spectra from camo and foliage
samples suggest, however, that these concerns might not be fully justified. Under full sun and in the shade, spectra from 300
to 500 nanometers (nm) (i.e., UV and visible blue light) showed that camo samples containing FWA matched the foliage reasonably
well. No evidence of a major problem caused by the FWA was detected, and no significant need for the use of UV absorbing dyes
to block the action of FWA was found." (http://www.ncbi.nlm.nih.gov/m/pubmed/8320420/)
So if I understand it correctly fabrics containing those brighteners absorb uv light and radiate blue visible light. So that
does mean that it reduces the reflection of uv radiation making it darker and less shiny for uv vision.
If I imagine it correctly this results in a more effective camouflage for shade/dusk/dawn hunting situations. But what does it mean if a deer sees you at bright daylight. It's said that it sees blue more intensely than humans. Are we appearing with a blue glow or just a blue touch or doesn't it matter because all colours (remember deer have got a limited colour vision) are being reflected and shining bright in the sun.
For me it is for sure that you shouldn't choose your hunting camo too bright but darker. Best with quite an amount of not reflecting black in it maybe based on a red/brown background.
Most important is to keep out of the wind (direction), not to make fast movement and try to keep in the shadows!