A Guide to Photoluminescent Material
Through the group of companies that make up Warnstar Sign and Print, we manufacture our own photoluminescent material and produce a wide range of safety signs and safety way guidance systems for both the terrestrial and marine markets.
What is photoluminescence?
Photoluminescence is the phenomenon whereby luminescence (spontaneous emission of light by a substance not resulting from heat; or “cold light”) is induced by the absorption of visible light, UV or infrared radiation.
Often abbreviated as PL, Photoluminescence is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photons that excite electrons to a higher energy level in an atom), hence the prefix photo-. However, it is a non-radioactive process and requires no battery back-up and has almost unlimited charge and discharge cycles.
In a more simplified explanation, a photoluminescent material absorbs and stores photons (‘particles’ of light) from a light source. When that light source is removed, the stored energy is released as visible light and ‘glows in the dark’.
The ‘glow in the dark’ properties make it very useful for manufacturing safety products, especially signs and safety way guidance systems. In the event of light failure, photoluminescent safety signs and products are still visible for a certain length of time.
There are different grades of material depending on how bright the glow is and how long it lasts at a certain level before fading. The photoluminescence of signage products is renewable. Once the light source is re-instated the product is re-charged.
The Grades of Photoluminescent Material
The Photoluminescent Safety Products Association (PSPA) classification system is based on luminance decay data as given when tested according to ISO 17398 (also ISO 16069) illuminated with 1000 lux from Xenon D75 (Daylight) source for 5 minutes (very similar to DIN 67510 Part 1 and ASTM E 2073-10 also with this illumination and time.
Legislation says that terrestrial-based safety products have to be manufactured from grade/Class C photoluminescent material to be compliant with BS ISO 16069, although for marine environments Class B is the accepted norm.
Safety & Traceability of Your Photoluminescent Products?
Unlike many signage manufacturers, we don’t just print photoluminescent signs, we also manufacture the material too. Our Telglow™ material is used to manufacture a wide range of safety products and SWGs and as an ISO 9001:2015 accredited company, we can produce a cost-effective product with full traceability.
The Standards & Legislation
The following standards are those most relevant for use in terrestrial applications.
BS ISO 16069:2017 Graphical Symbols – Safety Signs – Safety way guidance systems (SWGS)
A safety way guidance system coordinates a complex range of safety products in order to provide a continuous and conspicuous, unbroken route to safety that allows people to evacuate occupied areas with minimum risk. ISO 16069 indicates when and where it is appropriate to use photoluminescent materials as part of an SWGS and defines minimum performance requirements for this application.
DIN 67510 Phosphorescent Pigments and Products
This German standard is the industry norm for the measurement and assessment of photoluminescent products. DIN 67510 Part 1 defines a method where samples are exposed for 5 minutes to a Xenon light source delivering
1000lux of light energy. The light is extinguished and the afterglow measured in millicandella’s per m² (mcd/m²) at defined time intervals, until extinction is achieved at a level of 0.32 mcd/m².
DIN 67510 Part 4 defines performance levels and is used by ISO16069 to specify minimum performance requirements. When tested to DIN 67510-1 the photoluminescent must have a minimum luminance, after withdrawal of the excitation light source, of 20 mcd/² at 10 minutes, 2.8 mcd/² at 60 minutes and a minimum time to 0.32mcd/m² of 340 minutes. This information is usually annotated as follows: 20/2.8 – 340 / DIN67510-1.
If you would like advice on choosing the right photoluminescent products for you, please get in touch Tel 01737 762400.
This was first published on our sister site Signs For Safety