What Does Weathering Test Mean?
A weathering test is a system for determining weathering characteristics of materials and coatings. Weathering testing is used to improve product durability and is also a tool for decision making. Such tests can be used to predict durability or to monitor changes in mechanical properties during weathering of materials.
Weathering is the adverse response of a material or product to climate, often causing unwanted and premature product failures. To prevent premature product failure and degradation, chemical or mechanical stabilization is used, and to assess the durability of a material, weathering tests are used.
Corrosionpedia Explains Weathering Test
Destruction from weathering or corrosion occurs both outdoors and indoors, and its severity can vary greatly depending on the climate. It is impractical to measure the weathering characteristics of materials in all of the world's climates. The major marketing area of the material should be taken into account when selecting appropriate climates and locations for weathering tests.
Besides natural weathering, several test methods have been developed using artificial light sources to provide accelerated test procedures. These are:
- Natural weathering - Involves placing samples on inclined racks oriented toward the Sun. Sites used for this type of testing are usually in tropical areas. Despite harsh conditions, testing takes several years before significant results are achieved.
- Accelerated natural weathering - To speed up the weathering process, accelerated natural testing can be applied. One method uses mirrors to amplify available UV radiation. A variety of environmental chambers are also used in conjunction with industry standards.
- Laboratory accelerated weathering - The process is accelerated through the use of specially designed weathering chambers. Gas-discharge lamps (e.g. xenon arc lamps), electric arc (carbon) or fluorescent lamps are used to simulate/accelerate the effects of sunlight.
All methods are based on regular monitoring of characteristics reflecting an aging process like:
- Mechanical properties:
- Elongation at break
- Tensile properties
- Impact strength
- Visible characteristics:
- Crack formation
- Changes in color or gloss
Natural weathering tests deliver the most accurate and reproducible data. However, their duration can be very lengthy, which often results in selection of an artificial weathering method.
Since weathering depends on solar radiation (light energy), temperature and moisture, these factors should be considered when testing is performed.