This page contains a Flash digital edition of a book.
www.greenbuildermag.com 08.2012


~ How-to ~ 42 PAINT LAST LONGER


Years of research point clearly at the things that can or shorten or extend the lifespan of a coating. It all comes down to sunlight, moisture and the amount of surface area.


O 1


FTEN, WHEN PEOPLE think about siding their homes with a “green” product, they don’t spend enough time thinking about paint. But acrylic paint has a sky-high environ-


mental footprint—about 61 megajoules per kilogram. Compare that to cement at 5.6 MJ/kg, or PVC at 80 MJ/kg. Any material with that kind of enviromental cost had better last as long as possible. So we went to the research—much of it conducted by the forest products industry and the military—to fi nd out why paints last or fail. Experts such as William Feist (see sources) divide paint durability into two aspects: “the ability of the fi n- ish to develop initial mechanical adhesion and the ability of the fi nish to maintain that adhesion.” Here’s how to maximize paint adhesion and durability.


2 MAKE EXTERIOR


What lies beneath? A preprimed surface is likely to hold its covering longer than unprimed, but only if the mosture level of the wood (or fi ber cement) beneath it at the time of priming was in the optimal range, typically 15% or less.


3


Keep it covered. Ultraviolet rays break down wood surfaces remarkably quickly. Wood should not be left out in the sun, nor left bare (like this) for any length of time.


Play rough. Textured surfaces have more “tooth” to keep paint from bubbling or peeling. A textured surface also has more overall surface area, so it has more places for paint to “bond.” But rough, textured surfaces are harder to coat eff ectively. Take special care that all angles are covered.


Seal nailheads. After sanding off any rust, nails and fasteners should be counterset and coated with a rust-resistant metal primer. Fill the fastener holes with wood putty before the exterior primer goes on.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76