Meaning
The total amount of light that falls on a surface over a specific period is quantified through a measurement of illumination intensity and time. Distribution centers and retailers monitor lux exposure to prevent the photofading of sensitive merchandise like clothing, cosmetics and food. This metric helps in predicting how long a product can remain on display before its appearance begins to change.
It is calculated by multiplying the illuminance in lux by the number of hours the material is exposed.
Cumulative Dose
Records of light levels show the total energy absorbed by the surface of the goods. When lux exposure reaches a certain threshold, the chemical bonds in the pigments start to break down. High intensity lighting for a short period can cause the same damage as low intensity lighting over a long period.
Managers use this information to rotate stock and ensure that no single item stays in a high light zone for too long. Data from light sensors allows for the adjustment of the lighting schedule to minimize the dose.
Degradation Risk
Materials vary in their sensitivity to light based on their chemical composition and the presence of protective coatings. High lux exposure poses a greater risk to natural fibers and organic dyes than to synthetic materials. Testing determines the reciprocity of the material, which shows if the damage is strictly proportional to the total dose.
If the risk is high, additional uv filters may be installed on the light fixtures.
Measurement Procedure
Accurate assessment requires the placement of sensors at the same level as the products on the shelf. Because lux exposure can vary significantly between the top and bottom of a display, multiple readings are taken to find the average. Regular calibration of the equipment ensures that the data used for stock management is reliable.
