ASTM Testing
ASTM Test Methods
Organized in 1898, ASTM International (ASTM) is one of the largest voluntary standards development systems in the world. It is a not-for-profit organization which provides a forum for producers, users, ultimate consumers and those having a general interest (representatives of government and academia) to meet on common ground and write standards for materials, products, systems and services.
Crosshatch Adhesion Test
The test performed was the rigorous Crosshatch Adhesion Test, ASTM D3359. This test involves cutting a grid of 100 squares into the coated panels. A pressure sensitive tape is applied over the grid, and then rapidly peeled away. The number of squares remaining on the panel gives a relative percentage value of adhesion.
Accelerated Weathering by QUV
Accelerated weathering simulates damaging effects of long term outdoor exposure of materials and coatings by exposing test samples to varying conditions of the most aggressive components of weathering - ultraviolet radiation, moisture and heat. A QUV test chamber uses fluorescent lamps to provide a radiation spectrum centered in the ultraviolet wavelengths. Moisture is provided by forced condensation, and temperature is controlled by heaters. No direct correlation can be made between accelerated weathering duration and actual outdoor exposure duration. However, performance comparisons under the controlled conditions of accelerated weathering can be compared to documented performance of materials and coatings that have experienced extended periods of end use exposure.
Test Procedure : Test samples are mounted in the QUV and subjected to a cycle of exposure to intense ultraviolet radiation followed by moisture exposure by condensation. Various cycles are defined depending upon the intended end use application - for example, a typical cycle for automotive exterior applications would be 8 hours UV exposure at 70° C followed by 4 hours of condensation at 50° C. These cycles would be continued for extended periods of time - up to thousands of hours - simulating even longer periods of time in the real world.
Specimen Size :
Typically, flat plaques or disks are used for accelerated weathering studies. The standard sample holders can hold one sample 3 x 12 inches (75 x 300 mm) or two samples 3 x 6 inches (75 x 150 mm).
Accelerated weathering provides exposed samples for comparison to unexposed control samples. Several exposure times (such as 500, 1000, and 2000 hours) also can be compared to each other. Depending upon the performance requirements of concern, such a comparison may involve measurements of Haze, Transmission, Yellowness Index, Color Change, and/or physical properties such as Impact Strength.
A PDF document detailing these test results is available upon request. This document is a complete listing of all tests and results as well as before and after photographs on a wide variety of materials.
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ASTM Testing