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Tuesday, 17 September 2019
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Raw materials & technologies, Production and testing

Method to help speed the introduction of new coatings products

Thursday, 16 January 2014

OEMs, material suppliers and test equipment manufacturers have developed a new ASTM test method for transportation coatings.

The new ASTM test method has been developed for transportation coatings
Source: Sfondilias - Fotolia.com

The new ASTM test method has been developed for transportation coatings
Source: Sfondilias - Fotolia.com

It was developed to address the deficiencies of historical tests used for transportation coatings, especially automotive coatings.

Standard improves accuracy

The "ASTM D7869-13 Standard Practice for Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings” method is 30 to 40% faster than the previous test standard used for many OEMs, and improves the accuracy to nearly 100% in predicting coating service life compared to less than 50% with the previous standard. Industry implementation of this new test can speed new product development, and aid in the development of better overall products for the coating industry. This test can be used for automobiles, aircrafts, trucks and rail cars.

Stresses include long water exposures

BASFbrought key partners together, developed the critical coating formulas for testing, and conducted several important experiments in the physical test laboratories, which resulted in the new test method. It simulates physical and environmental stresses that an exterior transportation coating is exposed to in a subtropical climate. These stresses include long water exposures, wet/dry cycling, and high dosages of solar radiation, all of which have been shown to cause severe coatings deterioration.

Test conditions consist of a primary test and a sub-cycle

The primary test includes two long water exposures and a single, long light exposure with precise spectral match to daylight. The sub-cycle consists of shorter alternating water and light exposures and is designed to simulate cyclic stresses such as cracking and surface erosion. These two cycles are designed to replicate the common types of coatings failures driven by the interaction of photo-oxidation during daylight and hydrolysis during water exposure. Together, these failures can lead to gloss loss, color change, adhesion, blistering and cracking.

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