Luminance is the photometric dimension that human beings recognize as brightness, in other words it is the intensity of light per area. The factors that determine how brightly a photoluminescent product performs are:
- type of pigments
- quantity of pigment
- type of activating light source
- intensity of activating light on product surface
- length of activation (time)
PERMALIGHT® controls the first two factors. We work with high quality, patent-protected strontium-oxide aluminate pigments and use the appropriate amounts of pigment to accomplish the matching code or standard compliances.
To evaluate the performance of our photoluminescent products, we measure the luminance with a calibrated photometer (luminance measurement instrument) per ASTM E2073 Standard Test Method for Photopic Luminance of Photoluminescent (Phosphorescent) Markings and per standard DIN 67510 parts 1 and 2. Luminance is measured in milli candela per square meter (mcd/m²).
Per ASTM E2073-10, the luminance is measured at 10, 60 and 90 minutes in full darkness following previous light activation by 1 foot-candle (10.8 lux) of fluorescent lighting for 60 minutes.
Per German DIN 67510 Part 1, the luminance is measured at 2, 10, 30 and 60 minutes in full darkness following previous light activation by 1000 lux (92.9 foot-candle) of xenon lighting for 5 minutes. This German standard additionally indicates the decay time as 0.3 mcd/m², 100-times the theoretical value human eyes can perceive.
Click here to see an overview of luminance values.
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