Strontium silicate can be added to glass so that it glows after it is exposed to bright light. One source says their green and blue-green colors can emit light for up to 20 hours. Blue will only emit light for up to 12 hours. Other colors have lower glow times. All colors dim as the hours pass, so even a green may be quite dim at 15 hours compared to the initial glow. I can find no info on how many years the active ingredient continues to store and emit light. Try asking the manufacturer.

Great research! Thanks for the feedback -- I am starting to feel more confident about moving forward with this project.