Lume
Encyclopedia
Lume is a short term for the luminous phosphorescent
Phosphorescence
Phosphorescence is a specific type of photoluminescence related to fluorescence. Unlike fluorescence, a phosphorescent material does not immediately re-emit the radiation it absorbs. The slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum...

 glowing solution applied on watch dials. There are some people who "relume" watches, or replace faded lume. Formerly lume consisted mostly of radium
Radium
Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226,...

; however, radium is radioactive and has been mostly replaced on new watches by less bright, but less toxic compounds.

Common pigments used in lume include the phosphorescent
Phosphorescence
Phosphorescence is a specific type of photoluminescence related to fluorescence. Unlike fluorescence, a phosphorescent material does not immediately re-emit the radiation it absorbs. The slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum...

 pigments zinc sulfide
Zinc sulfide
Zinc sulfide is a inorganic compound with the formula ZnS. ZnS is the main form of zinc in nature, where it mainly occurs as the mineral sphalerite...

 and strontium aluminate
Strontium aluminate
Strontium aluminate is a solid odorless, nonflammable, pale yellow powder, heavier than water. It is chemically and biologically inert. When activated with a suitable dopant , it acts as a photoluminescent phosphor with long persistence of phosphorescence...

. Use of zinc sulfide for safety related products dates back to the 1930s. However, the development of strontium oxide aluminate, with a luminance approximately 10 times greater than zinc sulfide, has relegated most zinc sulfide based products to the novelty category. Strontium oxide aluminate based pigments are now used in exit signs, pathway marking, and other safety related signage.

Strontium aluminate based afterglow pigments are marketed under brandnames like Super-LumiNova
Super-LumiNova
Super-LumiNova is a brand name under which strontium aluminate based non-radioactive and non-toxic photoluminescent or afterglow pigments for illuminating markings on watch dials, hands and bezels, etc. in the dark are marketed...

, w@tchlume, NoctiLumina, and Glow in the Dark (Phosphorescent) Technologies.

External links

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