As per Atsko @
http://www.atsko.com/u-v-killer-information/:
"8. I've treated my camo and I still see a blue glow with my UV light source. Does this mean that it is not working?
Two possibilities exist. First, you may be seeing only visible blue and assuming it is UV.
U-V-Killer does not block visible blue because blocking it would change the appearance of your camo in the visible spectrum, (We assume that you chose a pattern & color that appear to be right for the terrain you hunt). The UV light source, even the flashlight we sell, has some visible violet wavelengths present, and if all UV is absorbed you will still see some of this visible violet. If you place a single drop of
U-V-Killer on a piece of brightened white paper or cloth and check it with the light source, you will see a dramatic difference because the brighteners are seen more on white. This demonstrates how effectively the absorber in
U-V-Killer is working. You may be assured that a good application of
U-V-Killer is just as effective on your camo and blaze orange.
The second possibility is that the application wasn't sufficient. Excess brighteners on the cloth will float to the surface of the U-V-Killer treatment. These excess brighteners must be removed by first washing with Sport-Wash. Wash twice if in doubt. Clean old detergent residue (which is full of brighteners) from washer by washing non-camouflage clothing inSport-Wash before washing your camo. Be sure to dry your camo (according to the care tag instructions) before treating with U-V-Killer . When applying U-V-Killer imagine you are applying a light coat of paint to the exterior surface. You want to cover every thread. If the spray is leaving spots, gaps, or streaks use a small brush, cloth, or even your hand to spread it back and forth. A bubbly white froth will remain visible up on the surface for a few minutes so that you can see that the coverage is complete. Check your progress with a black light.
To properly check your camo under black light you must use a true Ultraviolet fluorescent light source. There are at least three domestic manufacturers of Ultraviolet tubes, for example- General Electric "BL", Westinghouse "BL", and Sylvania "Black light 350". These black light tubes have radiation peaks at 350 nanometers. They will activate brighteners (like Tinopal by CIBA GEIGY) which are common in detergents. Manufacturers also offer "BLB" tubes. These are better because they have a blue filter to block visible wavelengths, they appear blue and are marked "BLB". They cost more but make it much easier to detect UV Brighteners. A true UV light source will enable you to make a complete check of all your hunting gear and provides a way to double check yourself once you have treated your equipment with U-V-Killer products."
