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Whatever Happened to … Acid Rain?

Air emissions and global warmingThis is the first in a series of posts under the general heading, “Whatever Happened to … ?” The idea is to revisit issues and opportunities of the past and help bring you up to date on what has been accomplished and what is still yet to be done. So … whatever happened to acid rain?

As it pertains to the prepainted metal market, and especially to metal roofing, acid rain became an accepted and understood phenomenon in the late 1970s and early 1980s. Badly corroded roofs were becoming more prevalent, but—like any new problem—it took some time to identify the root cause and to learn how to overcome the issue of red rusting on roofs. And, as with any root cause analysis, an early root cause declaration is usually challenged. Then more research is done, more challenges are raised, and, eventually, consensus is reached. Continue reading


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When “Just Right” Means “Uh-Oh”

nccaA while back, I wrote about the “just right” conditions necessary for the formation of fog. That particular post discussed the scattering of light, which is done by materials such as titanium dioxide (the principal pigment in white paint) and clouds (where water droplets do the scattering). The birds are chirping at sunrise and the vernal equinox has already passed, which means the sun is finally in the Northern Hemisphere and the days are getting longer and warmer—and all of this points to the beginning of another building season. That got me to thinking about a few other “just right” conditions that seem pertinent for this time of year. And, once again, water comes into play. Continue reading


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Science and ASTM

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! Continue reading


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The Next Great Thing: Part Two

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We left off last time mentioning two research reports, both of which discuss a functional material that might—someday—serve as a cooling device. No moving parts and no energy required to operate this device. Science fiction? Definitely not, but there is still much to be done before such a device becomes a commercial reality. But, for the moment, let’s not worry about such details.

At the 2015 CRRC Membership meeting, Aaswath Raman, Ph.D., from the Ginzton Laboratory at Stanford University, presented his work on sub-ambient cooling of sky-facing surfaces. To understand Dr. Raman’s work, picture a sheet of material with an exceptionally high solar reflectance (around 97%), mounted in a fixture on a roof in Phoenix. It has a shiny metal appearance. (Super-high reflectance is only possible with mirror-like materials.) Because the material has such a high reflectance, it will not absorb much incoming IR radiation, but it certainly will be heated by the surrounding hot desert air (convective heating). Since this shiny material is hot because of the desert heat, it is emitting plenty of IR radiation. Here is the actual installation. Continue reading


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The Next Great Thing: Part One

ImageforBlogPart1forwebIn the arena of university R&D, one often thinks, who cares? I certainly do. But in this and the next post, you will read about some fascinating work coming out of Stanford University. As a self-professed cynic, I would never mention “the next great thing” if I did not see some very real potential. There is, of course, a big valley between R&D and commercial reality, but from what I have heard and read … well, you be the judge.

One of these ideas that could fall into the “too good to be true” category is radiative cooling. Before you fear that I’ve taken leave of my senses, yes, I do understand that all objects radiate energy and will cool as a result. All cool-roofing codes contain an emittance requirement for this reason. Objects (such as painted metal roofing) with a high thermal emittance (>75%; a perfect emitter would be 100%) cool down faster than low-emittance materials such as shiny metal. When the sun sets, you want the roof to radiate as much heat as possible to the atmosphere as fast as possible. Of course, when the sun is beating down on the roof, you also want the roof to reflect as much heat as possible in the form of infrared radiation (IR), keeping the roof as cool as possible. That’s why both parameters—reflectance and emittance—are important in the cool-roofing arena. Continue reading


Scattering Sunshine

There is no investment you can make which will pay you so well as the effort to scatter sunshine and good cheer through your establishment.

– Orison Swett Marden (1850-1924)

770_4665645Scattering sunshine metaphorically is a great idea. The stress of the workplace places great burdens on people and spreading a little sunshine is a simple way to create a more positive environment. But scattering sunshine also has a far less romantic side to it.

Clouds and shaving cream are white, but they do not contain any white pigment. Driving through dense fog can be treacherous, but it’s just water! Bathroom mirrors also fog, especially if you take a really hot shower on a cold winter day. And titanium dioxide is a clear crystal, yet we call it a white pigment. Scattering of light explains all.

One can discuss scattering by pointing to detailed physics formulae, but that method produces more fog than clarity. I prefer the much simpler method that assumes that the brainy physicists have worked out all the details and that they can be trusted. If that works for you (and it certainly works for me), read on. Continue reading


The Growing Popularity of Metal Roofing in the Residential Market

The Metal Roofing Alliance estimates that more than 750,000 U.S. homeowners chose a metal roof to protect their families in 2015. The Metal Roofing Alliance reports that demand for sustainable, eco-friendly and energy-efficient home improvement materials continue to grow in North America.

According to a new study conducted by Dodge Data & Analytics, the residential metal roofing industry saw a big jump in market share last year, moving from approximately 8 percent in 2014, to 11 percent in 2015. The independent survey showed that between 2014 and 2015, the total demand for metal roofing increased from 11.7 million squares to 17.7 million squares. This is the second time residential metal roofing has achieved double-digit market share in the re-roofing segment. Metal roofing is second only to asphalt shingle roofing in the remodeling market. Asphalt market share dropped 2 points overall, and it now makes up 78 percent of the U.S. market.

When the Metal Roofing Alliance began its national consumer awareness campaign in 1998, metal only made up 3.7 percent of the re-roofing market. The organization’s consistent effort to educate consumers about investment-grade metal roofing has helped to build this market.

Survey Data Continue reading