UV testing is carried out on polymer products or components (for example plastic, fiber glass, painted surfaces…) to assess their ability to withstand UV radiation from the sun for their expected lifetime while also maintaining their usual properties.
To do so, the item could be placed in normal sunlight for a long period of time to examine the effects of the sun on the polymer.
Typically, when a new product is developed and its resistance to sun rays needs to be verified, some samples are subjected to accelerated UV testing in a UV testing lab, which artificially recreates a long period of time under UV radiation bombardment in a short and convenient timescale.
How the UV testing works in a lab
Image credit: By Ishikawa Own work, CC BY-SA 3.0, Link
Both UVA and UVB lamps are typically used to simulate natural sunlight, with UVA being the predominant source of radiation.
The pieces being tested are added to a QUV test chamber and remain there for a different amount of time to simulate a number of years of UV exposure due to accelerated UV testing. Here is an example of the test times offered by some labs. You can see, for instance, that 8 years of UV exposure can be simulated in around 480 hours:
The UV test will be checking that the plastic has retained its regular properties, such as color and impact & flexural strength (the properties to check are highly dependent on the type of product and its application).
Note, it is common for moisture & heat testing also to take place during the test – all three functions being performed by the QUV chamber.
Common testing standards
You should inquire as to which standard/s the testing lab is using as they can differ slightly and you need to know for the sake of compliance. Here are some useful links:
- ASTM D4329 – 13
Standard Practice for Fluorescent Ultraviolet (UV) Lamp Apparatus Exposure of Plastics
- ASTM D5208 – 14
Standard Practice for Fluorescent Ultraviolet (UV) Exposure of Photodegradable Plastics
- ASTM D4587-11(2019)e1
Standard Practice for Fluorescent UV-Condensation Exposures of Paint and Related Coatings
- ISO 4892-3:2016(en)
Plastics — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps
- IEC 60068-2-5 Ed. 3.0 en:2018
Environmental Testing – Part 2-5: Tests – Test S: Simulated Solar Radiation At Ground Level And Guidance For Solar Radiation Testing And Weathering
Also, this standard applies to the use of natural sunlight as a comparison:
- ASTM D4364 – 13
Standard Practice for Performing Outdoor Accelerated Weathering Tests of Plastics Using Concentrated Sunlight