If you leave such hoochies as Purple haze, Jellyfish, Green haze, Pink Haze out in the hot summer sun for a period.......the sunlight will "cook" the UV pigment and turn the hoochy from faintly bluish to full out opaque light blue. You can also see this effect in hoochies of that type hanging in a store for too long. The guys that sell them say it doesn't matter....the hoochy will work just as good even though it is now totally opaque. I don't believe them. Once the UV pigment is "cooked", it doesn't work right. UV translucent flashers and UV in "hard" plastic tackle seems to fair a little bit better. UV flashers don't seem to cook pigment.......but if left out in the sun for a period you can see them starting to drastically change color temporarily. The idea is that the UV component "reflects " UV light at depth. Once the UV pigment is "cooked" or destroyed ........it won't do it's job.