Through countless experiements, we have combined epoxy resin and 100% all-natural glow powders to create the longest lasting glow effects possible. Depending on the color of the powder, our vases could still be glowing several hours later. Furthermore, our vases don't require direct sunlight to charge. Depending on the type of bulb and wattage, a vase can be fully charged within 10 minutes. To activate glow, place under any light bulb, 40 to 100 watts; no closer than 6 inches for 5 to 10 minutes, turning once half way through, Time varies depending on wattage, turn off the light and enjoy. Our vases can literally be charged thousands of times. No batteries to replace!