From what I gather, the ability of the luminesent paint to radiate light is directly related to the amout of the stuff (to a point of diminishing returns). Of course it also depends on, for powder, the grain size. The larger the grain, the longer and brighter it will glow. After looking at the powder it might be a viable option. But you'd have to cover it with epoxy, as they suggest, which would produce a glossy button. Not bad at night but might look tacky in the daytime. Also, you have to remember that the color of the stuff when it's not glowing is white. So you'd have a white button durring the day.