UV Accelerated Weathering Tester is another kind of light aging test equipment that simulates light. It mainly simulates ultraviolet light in sunlight. At the same time, it can also reproduce the damage caused by rain and dew. The equipment conducts the test by exposing the material to be tested to a controlled alternating cycle of sunlight and moisture while increasing the temperature. The equipment uses ultraviolet fluorescent lamps to simulate sunlight, and it can also simulate the effects of moisture through condensation or spraying.

It only takes a few days or weeks, and the device can reproduce the damage that takes months or years outdoors. The damage caused mainly includes fading, discoloration, decrease in brightness, chalking, cracking, blurring, embrittlement, decrease in strength and oxidation. The test data provided by the equipment is of great help in the selection of new materials, the improvement of existing materials, or the evaluation of composition changes that affect the durability of the product. The equipment can predict very well the changes that the product will encounter outdoors.

Although ultraviolet light (UV) only accounts for 5% of sunlight, it is the main light factor that causes the durability of outdoor products to decrease. This is because the influence of sunlight's photochemical reaction increases as the wavelength decreases. Therefore, when simulating the destructive effect of sunlight on the physical properties of the material, it is not necessary to reproduce the entire sunlight spectrum. In most cases, only short-wave UV light needs to be simulated. The reason why UV lamps are used in UV accelerated weathering testers is that they are more stable than other lamps and can better reproduce test results. Fluorescent UV lamps are used to simulate the influence of sunlight on physical properties, such as brightness drop, cracking, and peeling. Most of these UV lamps mainly produce ultraviolet light, rather than visible light and infrared light. The main difference between lamps is the difference in the total UV energy they produce in their respective wavelength ranges. Different lamps will produce different test results.