Differences in the Applications of UV-A, UV-B, UV-C, and UV-D?

What is UV Aging Test?

UV aging test is a weather resistance test conducted by exposing materials to controlled high-temperature light using UV lamps to simulate the damage caused by solar ultraviolet radiation. This test uses UV lamps to mimic the sun's radiation and employs condensation and water spray to simulate dew and rain. In just a few days or weeks, UV radiation equipment can reproduce damage that would take months or even years to occur outdoors, including fading, color changes, loss of luster, chalking, cracking, wrinkling, blistering, embrittlement, strength reduction, oxidation, etc. The test results can be used to select new materials, improve existing ones, or evaluate changes in material formulations.

Which Products Require UV Aging Test?

The scope of products requiring UV aging test is extensive, encompassing sectors such as rubber, plastics and their products, coatings, paints, dyes, fabrics, printed packaging, adhesives, metals, electronics, electroplating, cosmetics, and more.

Testing Principles of UV Aging Equipment

UV aging equipment simulates damage caused by solar ultraviolet radiation by exposing materials to controlled high-temperature light for weather resistance testing. It uses UV lamps to replicate the sun's radiation and employs condensation and water spray to simulate dew and rain. In just a few days or weeks, UV radiation equipment can reproduce damage that would take months or even years to occur outdoors, including fading, color changes, loss of luster, chalking, cracking, wrinkling, blistering, embrittlement, strength reduction, oxidation, etc. The test results can be used to select new materials, improve existing ones, or evaluate changes in material formulations.

Solar Simulation: UV aging equipment utilizes fluorescent UV lamps to simulate the critical short-wave ultraviolet region of sunlight, typically from 365nm to 295nm, reproducing the aging effects of solar radiation on material physical properties.

Commonly used UV lamp types include:

UVA-340 (Most Common): Simulates the critical short-wave ultraviolet region of sunlight from 365nm to 295nm, primarily used for testing outdoor products.

Irradiance Setting Reference for UVA-340: 0.68W/m², equivalent to the maximum solar irradiance on a summer noon, yielding rapid results.

UVA-351: Simulates the ultraviolet component of sunlight passing through window glass, used for testing indoor products.

UVB-313 (Rarely Used): Emits wavelengths between 280nm and 315nm, with a peak at 313nm.

Irradiance Setting Reference for UVB-313: 0.67W/m², a typical irradiance level for UVB-313 lamps, enabling very rapid testing. It is applied in quality control or durability testing of materials with good resistance. However, UVB-313 lamps can induce accelerated aging in materials, but the shorter wavelengths beyond the solar cutoff point may produce unrealistic results for many materials, thus they are rarely used.

Humidity Simulation: UV aging equipment generally offers two humidity simulation methods: condensation and spray.

Condensation: The most widely used method for simulating outdoor humidity erosion.

In many outdoor environments, materials can be exposed to moisture for up to 12 hours daily. Research indicates that dew, rather than rain, is the primary factor contributing to outdoor humidity. UV aging equipment simulates outdoor humidity erosion through a unique condensation function. During the condensation cycle, a water tank at the bottom of the tester is heated to generate water vapor. This hot water vapor maintains a relative humidity of 100% in the tester at elevated temperatures. In the design of UV aging testers, the test specimens actually form the side walls of the tester, with their back surfaces exposed to the laboratory air. The cooling effect of the laboratory air causes the specimen surface temperature to be a few degrees lower than the water vapor temperature, ensuring continuous condensation of water vapor on the specimen surface.

Water Spray: In certain practical application scenarios, such as when heat accumulated under sunlight is rapidly dissipated by sudden rain showers, materials can experience rapid temperature changes, resulting in thermal shock. This thermal shock is a critical test for many materials. Additionally, some materials are susceptible to mechanical erosion from rainfall. The water spray function in UV aging testers can simulate both thermal shock and mechanical erosion.

Common Standards for UV Aging Test

Plastics: GB/T 16422.3 (ISO 4892-3): Plastics - Methods of Exposure to Laboratory Light Sources - Part 3: Fluorescent UV Lamps.

Paints and Varnishes: GB/T 23987 (ISO 11507).

American Standards: ASTM G154. ASTM D4329.