Product Code Database
Luminous paint (or luminescent paint) is paint that emits Visible spectrum through fluorescence, phosphorescence, or radioluminescence.
The fluorescent chemicals in fluorescent paint absorb the invisible UV radiation, then emit the energy as longer wavelength visible light of a particular color. Human eyes perceive this light as the unusual 'glow' of fluorescence. The painted surface also reflects any ordinary visible light striking it, which tends to wash out the dim fluorescent glow. So viewing fluorescent paint requires a longwave UV light which does not emit much visible light. This is called a black light. It has a dark blue filter material on the bulb which lets the invisible UV pass but blocks the visible light the bulb produces, allowing only a little purple light through. Fluorescent paints are best viewed in a darkened room.
Fluorescent paints are made in both 'visible' and 'invisible' types. Visible fluorescent paint also has ordinary visible light pigments, so under white light it appears a particular color, and the color just appears enhanced brilliantly under black lights. Invisible fluorescent paints appear transparent or pale under daytime lighting, but will glow under UV light. Since patterns painted with this type are invisible under ordinary visible light, they can be used to create a variety of clever effects.
Both types of fluorescent painting benefit when used within a contrasting ambiance of clean, matte-black backgrounds and borders. Such a "black out" effect will minimize other awareness, so cultivating the peculiar luminescence of UV fluorescence. Both types of paints have extensive application where artistic lighting effects are desired, particularly in "black box" entertainments and environments such as theaters, bars, shrines, etc. The effective wattage needed to light larger empty spaces increases, with narrow-band light such as UV wavelengths being rapidly scattered in outdoor environments.
This type of paint has been used to mark escape paths in aircraft and for decorative uses such as the "stars" applied to walls and ceilings. It is an alternative to radioluminescent paint. Kenner's Lightning Bug Glo-Juice was a popular non-toxic paint product in 1968, marketed at children, alongside other glow-in-the-dark toys and novelties. Phosphorescent paint is typically used as body paint, on children's walls and outdoors.
When applied as a paint or a more sophisticated coating (e.g. a thermal barrier coating), phosphorescence can be used for temperature detection or degradation measurements known as phosphor thermometry.
Because of safety concerns and tighter regulation, consumer products such as clocks and watches now increasingly use phosphorescent rather than radioluminescent substances. Previously radioluminicesent paints were used extensively on watch and clock dials and known colloquially to watchmakers as "clunk". Radioluminescent paint may still be preferred in specialist applications, such as . Hazards from luminised timepieces in watch/clock repair , UK Health and Safety Executive
Radium paint used zinc sulfide phosphor, usually trace metal dopant with an activator, such as copper (for green light), silver (blue-green), and more rarely copper-magnesium (for yellow-orange light). The phosphor degrades relatively fast and the dials lose luminosity in several years to a few decades; clocks and other devices available from antique shops and other sources therefore are not luminous any more. However, due to the long 1600 year half-life of the Ra-226 isotope they are still radioactive and can be identified with a Geiger counter.
The dials can be renovated by application of a very thin layer of fresh phosphor, without the radium content (with the original material still acting as the energy source); the phosphor layer has to be thin due to the light self-absorption in the material.
Promethium-based paint was used to illuminate Apollo Lunar Module electrical switch tips, the Apollo command and service module hatch and EVA handles, and control panels of the Lunar Roving Vehicle.
Tritium light sources are most often seen as "permanent" illumination for the hands of wristwatches intended for diving, nighttime, or tactical use. They are additionally used in glowing Novelties , in self-illuminated , and formerly in fishing lures. They are favored by the military for applications where a power source may not be available, such as for instrument dials in aircraft, , lights for map reading, and sights for weapons.
Tritium lights are also found in some old rotary dial telephones, though due to their age they no longer produce a useful amount of light.
|
|
