colors that jump out at you from t-shirts
and magazine racks, much bright
er than anything surrounding them. Day-Glo is effective simply because it is shocking; our eyes aren't used to seeing colors that that fluoresce
under normal light
. Which is to say, under natural and in-door light, they absorb light that's of such a high wavelength
that we can't see it, and re-release the light at a lower wavelength, which we see. Thus, things containing Day-Glo pigment
s seem to release light that wasn't there before; they glow
Day-Glo is a trademark of the Day-Glo Color Corporation, of Cleveland, Ohio. Their officially sanctioned colors are: Aurora Pink, Neon Red, Rocket Red, Fire Orange, Blaze Orange, Arc Yellow, Saturn Yellow, Signal Green, Horizon Blue, and Corona Magenta. These names are also, of course, trademarked. Day-Glo pigments can be impregnated in many polymers, from resins, for making inks and dyes, to hard plastics, for making toys and the like. The Day-Glo corporation sells both inks and raw pigment.
There are knock-off Day-Glo colors, I used to work for a printing company that used the official Day-Glo color swatches in their catalogs, and then used ink from somewhere in Mexico for the actual production. The process used by Day-Glo to make fluorescent pigments is patented, and the knock-off companies are no doubt in violation of the patents. Notably, the process involves such dangerous chemicals (cyclohexamine springs to mind) that the company has its own EPA Risk Management Plan, #4635.
The chemicals that give Day-Glo its glow tend to decay rapidly in the presence of light. The aforementioned printing company recommends that only temporary bumper stickers be printed with fluorescent inks, as they all fade to white after about three months of sunlight. Color decay is also about half the reason that none of your Day-Glo crap from the 80s looks good anymore ;-)