The first use of radioluminescence was in luminous paint containing radium, a natural radioisotope.  Beginning in 1908, luminous paint containing a mixture of radium and copper-doped zinc sulfide was used to paint watch faces and instrument dials, giving a greenish glow. Phosphors containing copper-doped zinc sulfide (ZnS:Cu) yield blue-green light; copper and manganese-doped zinc sulfide (), yielding yellow-orange light are also used. Radium-based luminescent paint is no longer used due to the radiation hazard posed to persons manufacturing the dials. These phosphors are not suitable for use in layers thicker than 25 mg/cm, as the self-absorption of the light then becomes a problem. Zinc sulfide undergoes degradation of its crystal lattice structure, leading to gradual loss of brightness significantly faster than the depletion of radium.
ZnS:Ag coated spinthariscope screens were used by Ernest Rutherford in his experiments discovering the atomic nucleus.
Radium was used in luminous paint until the 1960s, when it was replaced with the other radioisotopes mentioned above due to health concerns.  In addition to alpha and beta particles, radium emits penetrating gamma rays, which can pass through the metal and glass of a watch dial, and skin.  A typical older radium wristwatch dial has a radioactivity of 3–10 kBq and could expose its wearer to an annual dose of 24 millisieverts if worn continuously.  Another health hazard is its decay product, the radioactive gas radon, which constitutes a significant risk even at extremely low concentrations when inhaled.  Radium's long half-life of 1600 years means that surfaces coated with radium paint, such as watch faces and hands, remain a health hazard long after their useful life is over.  There are still millions of luminous radium clock, watch, and compass faces and aircraft instrument dials owned by the public.  The case of the "Radium Girls", workers in watch factories in the early 1920s who painted watch faces with radium paint and later contracted fatal cancer through ingesting radium when they pointed their brushes with their lips, increased public awareness of the hazards of radioluminescent materials, and radioactivity in general.