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Science and ASTM

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ASTM logoYou may think that that standards development in ASTM is a slow process—as it tends to be in most associations with volunteers. You may think ASTM-ers talk endlessly about the stickiness of tape or the problem with the precision of the pencil hardness test. Yes, there is plenty of that. There is also the development of new standards when new technology becomes established.

Anyone developing a piece of testing equipment in the paints and coatings industry—or the medical industry or the building and construction industry—can see the value of having an ASTM standard available to clarify its use and to describe its precision. While all of these things are important, I have found that ASTM is also the one association where science can “happen” most readily. Hard to believe? Read on!

Let’s think about service life prediction. In the coil coating industry, 75% of what we do involves building products. Many of these products provide aesthetic appeal, and we strive in our industry to develop technologies that can survive the rigors of heat and cold, moisture cycling, and sunlight. Many products include a warranty. A warranty guarantees a level of performance over a certain period of time. This warranty is used to communicate to the consumer something about the quality of a product as well as the period of useful life of that product. I realize that I am not telling you something you don’t already know.

I also realize that you’ve likely taken the usual approach as you developed new technology: test the heck out of that product! Salt spray, humidity, thermal cycling, and, of course, lots of weathering, both real-time (stick panels on the fence and wait) and accelerated (put panels in a test cabinet and guess). The press for marketing new technology can often pose a problem to the more conservative of us who want to see a bit more real-time weathering data. (Translation: Can we wait another five years?)

Ours is not the only industry offering performance guarantees, yet painted metal products have some of the longest lifetime expectations. The problem, therefore, is to find a sound technique that affords the best approach to predicting the lifetime of a product. Two of the possible approaches are found in:

ASTM G166-00(2011): Standard Guide for Statistical Analysis of Service Life Data

ASTM G172-02(2010)e1: Standard Guide for Statistical Analysis of Accelerated Service Life Data

Both of these methods are based on a branch of statistics known as reliability theory. Nobody is interested in the average number of flights before an airplane wing falls off the plane, or the average amount of damaging UV radiation that leads to melanoma. In both cases you are most interested in the time to the first failure, not the average time of failure. I witnessed the earliest days (the ’90s) of the development of this approach as applied to coatings. I am not a bit embarrassed to admit that I left those meetings—stuffed with advanced math and the probabilistic approaches—completely baffled. About a year ago, when I first noticed the above two standards developed by ASTM Committee G03 on Weathering and Durability, I read through them and then re-read them. I realized that our G03 colleagues had “dummied down” the process (thankfully) into an intelligent set of procedures that do not require an advanced understanding of Weibull distributions.

Let’s assume the NCCA would like to investigate this technique, and let’s keep it simple and say that we would only study real-time weathering. I would probably contact Dr. David Burns of 3M, who had a large part in the development of the abovementioned standards. He is the kind of down-to-earth individual who would be happy to facilitate the process of understanding how to perform this kind of study. I might also tap an individual from the coatings industry who has utilized this procedure before (with coatings, not airplane wings) to learn from their past study. I could also talk with the coater and coatings suppliers who attend the ASTM D01.53 Coil Coated Metal meeting about how best to capture samples. All of the commercial weathering service providers attend these same ASTM meetings, so I might also ask them for free rack space. Free samples, free rack space, free tutors! This is how science “happens” at ASTM.

The paragraph above is full of “woulds,” “coulds,” and “mights.” Why don’t we—the NCCA—take the opportunity to work with the weathering experts within ASTM to investigate if ASTM G166 has merit for our industry? I know the theory is sound, but I have no idea about the logistics (e.g., number of samples, number of replicates, etc.) that could influence the practical use of this standard. This sounds like a great project for the NCCA Technical Committee to tackle.

I cannot mention ASTM without making my usual pitch: Membership is $75 per year (cheap), D01.53 Coil Coated Metals is the committee dedicated to our industry, and it meets along with all of the other D01 sub-committees—and the G03 weathering folks—twice a year (toward the end of January and again around mid-June). There is no fee to attend the meetings. The D01.53 meetings are always on a Monday morning, 9 a.m. to 1 p.m. The G03 people always attend the 9 a.m. portion of this meeting, which is dedicated to discussing coil coating weathering topics. It is hard to imagine a more concentrated group of people, all having a similar interest, crowded into a single room. Talk about one-stop shopping. An ASTM meeting is a convenient place to find a confluence of brainpower. When this occurs, science happens!

David Cocuzzi, NCCA Technical Director

April 2017

Post script: ASTM International was formerly known as the American Society of Testing and Materials. As their standards became internationally accepted, they rebranded themselves as ASTM International.

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