Assessment of Accelerated Weathering Tests at AAMA National Fall Conference Session
September 27, 2011The AAMA Alternate Accelerated Weathering Task Group met on Tuesday, September 27 at the Fall Conference in which Kurt Wood (Arkema) presented an update to ASTM’s D01.53 ten-year exposure study.
As an ASTM-NCAA joint project, the speaker discussed how both associations leveraged their resources to study the effects of weathering from five to ten years, and the overall focus was aimed at discussing the test methodology, statistical approach utilized and reviewing the final results. The basic structure of the study is formulated so that an abundance of data is collected and comparisons are made, thus statistics are generated by accelerated results approximating real-time results at particular time intervals.
The project was initiated by Dick Tucker, who asked the ASTM D01.53 Committee to determine the best advice to predict real–time weathering. Through a process of testing with modern coil coatings and a variety of technologies, the study was able to produce significant weathering properties. Study samples included plastisol, 70 percent PVDF, acrylic emulsion, silicone-modified polyester and regular polyester in a variety of colors. Additionally, the group was able to obtain real-time weathering predictions for Florida and Arizona by evaluating accelerated devices.
Of particular interest was the display of graphs which illustrate why ten years are needed to study the effects of weathering due to environmental factors and the theory of extrapolation due to time period.
Setting this study apart from others conducted in the industry is that 23 coatings and five chemistries were examined, whereas past studies have only evaluated a few coatings, often times only one. Additionally, researchers measured five parameters, compared to historically one parameter being evaluated. This study also evaluated seven exposure protocols, while past studies looked at just Florida weathering and one accelerated technique.
Researchers evaluated the data using the Spearman Rank, which is comprised of creating a ranking order. The data included unwashed data, gloss retention, Delta E data and chalk data. The conclusions drawn from the study noted that there is not an accelerated technique in existence that adequately predicts the long-term, real-time exposure. Five- and seven-year washed data adequately predicts ten-year real-time delta E and gloss retention washed results, and seven-year unwashed data sufficiently predicts ten-year real-time delta E and gloss retention unwashed results. Currently, there is no technique that predicts real-time chalking.
To view the presentation and to gain additional weathering information, visit the Members Only section of the AAMA website.
Thank you to our Silver Sponsor, Amesbury, and to all our Fall Conference sponsors for making this event a success.
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