With glow-in-the-dark toys, the phosphor combined in with plastic is normally going to be zinc sulfide or strontium aluminate, in keeping with HowStuffWorks. Strontium aluminate, the newer of the 2 substances, is very highly effective, with a glow that may final a number of hours.
Some gadgets — significantly previous watch or clock faces — have a persistently glowing display that doesn’t require charging. That is additionally created from phosphors, however with the addition of a radioactive materials like radium or tritium that persistently prices the phosphor rather than a lightweight supply.
Ideally, this radioactive aspect is utilized in such small quantities that it isn’t harmful for the particular person carrying or making the glowing merchandise. This hasn’t all the time been the case, nonetheless. Within the early twentieth century, many employees in clock factories making radium dials ultimately turned stricken with radiation poisoning, in keeping with Britannica. The ensuing scandal ultimately led to the creation of the U.S. Occupational Security and Well being Administration.