Surfaces That Age Gracefully

Some materials take on added visual interest as they age; others look progressively worse with the passing years.

1. Most species of wood deteriorate rapidly outdoors unless they arc stained or painted. A few species arc naturally resistant to decay, however, if left uncoated, they weather gradually to attractive shades of brown and gray. These species include cypress, redwood, white and red cedars, teak, and various tropical hardwoods. Weather slowly erodes the surfaces of these woods, requiring eventual replacement.

2. Outdoors, bright paint colors fade quickly to unattractive, streaky pastel shades. Clear coatings such as varnish allow sunlight to attack the wood beneath, and they peel off in a year or two. White paint, through an intentional chalking process, renews itself continually and tends to remain attractive. Earth color pigments and soft grays tend to hold their colors longer in sunlight than do brighter hues.

3. Among the metals, ordinary steel rusts away unless it has been painted. Stainless steel, especially in a brushed finish, retains its good looks indefinitely without painting. Aluminum forms a self-protecting oxide coating and does not corrode further, but this coating is thin, easily damaged, and looks splotchy. Through the process of anodizing, aluminum can be manufactured with a thick, durable coating of oxide that contains integral color of the designer's choice, and it will look good for decades. Copper forms a self-protecting oxide coating that is usually an attractive blue-green or black in color, depending on the pollutants in the atmosphere, and is a traditional choice for a metal that ages gracefully outdoors. Lead protects itself with a white oxide coating. A steel alloy is available that forms a tenacious, self-protecting coating of red-brown oxide and needs no painting. Weathering steel, lead, and copper tend to shed some of their oxide coatings, staining surfaces below, so care should be taken in detailing them to catch and drain all rainwater that has flowed over them before it can run onto such stainable surfaces as stone, concrete, wood, and glass.

4. In general, matte surfaces age more gracefully than glossy surfaces, which tend to weather rapidly to a matte finish on most materials. A mirror finish stainless steel panel, for example, soon grows dirty and its luster is obscured, whereas a matte finish stainless steel surface changes relatively little in appearance as it accumulates the same amount of dirt. Glossy paints lose their luster quickly in sunlight, chalking to a matte texture. The exceptions arc glass and glazed ceramic tiles. These lose some of their sheen as they grow dirty, but when washed they regain their lustrous surfaces and bright colors.

5. Smooth concrete surfaces—those formed against steel, plastic, or overlaid plywood—have a tendency to feature everv small flaw in the concrete.

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