Lume is a short term for the luminous
phosphorescent
Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluor ...
glowing solution applied on
watch dial
A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached b ...
s. There are some people who "relume" watches, or replace faded lume. Formerly, lume consisted mostly of
radium
Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rathe ...
; however, radium is
radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...
and has been mostly replaced on new watches by less bright, but less toxic compounds.
Common pigments used in lume include the
phosphorescent
Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluor ...
pigments
zinc sulfide
Zinc sulfide (or zinc sulphide) is an inorganic compound with the chemical formula of ZnS. This is the main form of zinc found in nature, where it mainly occurs as the mineral sphalerite. Although this mineral is usually black because of various ...
and
strontium aluminate
Strontium aluminate is an aluminate compound with the chemical formula (sometimes written as ). It is a pale yellow, monoclinic crystalline powder that is odourless and non-flammable. When activated with a suitable dopant (e.g. europium, written ...
. 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, Watchlume Co, NoctiLumina, and Glow in the Dark (Phosphorescent) Technologies.
Glow in the Dark (Phosphorescent) Technologies
References
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External links
Watchlume SiteEverest Watchworks, a relumerLUMINOSITY IN WATCHESLuminor 2020 – Debunking Panerai's fictional history of tritium-based lume (Perezcope.com)
Luminescence
Watches