UV Materials

[rabmax]

Hello all i was curing some UV resin on a fly that had an Olive dubbed body & ribbed with Olive spanflex.To your eye it was hard to see the spanflex rib until i turned the UV torch on.Under the UV the spanflex lit up like a Christmas tree.Does this mean the spanflex is a UV material.Cheers

[arkle]

The dye(s) used in the manufacturing process maybe u.v. reflective, but natural undyed spanflex is unlikely to be.

[danielp]

The whole UV thing is an absolute mine field, but a very interesting one. So many misconceptions and misleading data around. There is also no evidence I could find that an adult trout can even see UV! Makes you wonder why so many try and incorporate it and swear it improves a fly.

Fluorescence on the other hand, that could be properly useful. Lots of dyes that absorb UV (penetrates water very well as well) and emit a visible light colour. Those flies should be very interesting in the water.

[rabmax]

Originally Posted by danielp

The whole UV thing is an absolute mine field, but a very interesting one. So many misconceptions and misleading data around. There is also no evidence I could find that an adult trout can even see UV! Makes you wonder why so many try and incorporate it and swear it improves a fly.

Fluorescence on the other hand, that could be properly useful. Lots of dyes that absorb UV (penetrates water very well as well) and emit a visible light colour. Those flies should be very interesting in the water.

I have just tested a few flies tied with spanflex & it seems that the lighter colours shine the most.A few years ago i started adding a few turns of UNI fire orange thread to the bottom of most of my PTNs & found they out fished ones without.Last year i started doing the same with most of my emerger patterns & found the same too. .You almost need sun glasses on if you shine a UV torch at a fire orange tag.Would this be more likely florescence i am seeing when shinning a UV torch on certain materials. Cheers

[silver creek]

Originally Posted by danielp

The whole UV thing is an absolute mine field, but a very interesting one. So many misconceptions and misleading data around. There is also no evidence I could find that an adult trout can even see UV! Makes you wonder why so many try and incorporate it and swear it improves a fly.

Fluorescence on the other hand, that could be properly useful. Lots of dyes that absorb UV (penetrates water very well as well) and emit a visible light colour. Those flies should be very interesting in the water.

Agree.

Young trout can see into the UV spectrum compared to humans but they lose that ability in a few years. The ability to see into the IR spectrum does persist in adult trout.

For an in depth discussion of human vs fish color vision see:

"The three types of cones in the human eye each contain a photo-sensitive pigment that has the capacity to absorb a range of light wavelengths. Each cone is characterized by the wavelength at which maximum or peak absorption occurs. The three are as follows:


erythrolabe; peak absorption at 565nm; red
chlorolabe; peak absorption at 535nm; green
cyanolabe; peak absorption at 440nm; blue


Light wavelength is measured in nanometers and the visible spectrum ranges from 700nm (red) to 400nm (blue-violet).

Trout Eyes:


Trout, on the other hand, have four receptors, and the four peaks are 600nm, 535nm, 440nm, 355nm.


The second and third conform to the green and blue cones in humans. The first is similar to the human red, but its sensitivity range includes longer wavelengths than humans. The fourth is outside the band of wavelengths visible to humans and is referred to as "ultra-violet". However, the fourth class of cones disappears by the time a trout is two years old."

Conclusions:


1. Trout do indeed have color vision, but it is limited to relatively clear, shallow, water and short distances, so at close range, the trout can see the full detail of color.


2. Trout can discern differences in shades with the highest in blue, then red and then green shades.


3. The color red appears brighter than it does to humans, but quickly becomes black at greater distance.


4. The ability to detect color is greatly impaired and completely eliminated within 12 feet.


5. Impurities in the water or stained water makes colors less significant, but under these conditions, white will remain the best.


6. In the low light conditions of dawn or dusk, trout can not distinguish color. Black, then, becomes the most visible.


7. In clear water, fluorescent colors are more visible with red, orange and yellow being the most visible. In deeper waters, fluorescent yellow and green stand out the most. However, in stained water fluorescent is useless.

Color Vision in Trout Eyes | Trout University

Both flourescence and phosphorescence, the absorbtion of higher energy UV energy which is then released as light in the lower visible spectrum, I believe does make flies more visible in deeper water.

[midlander]

If a material absorbs UV light and emits a visible light wave it is fluorescent.

Ultra Violet light is invisible to the human eye as is Infra Red. If they were visible they would be ... er.. violet and ... um... red.

[rabmax]

I noticed when i had a search its a subject thats came up before too. Cheers all