Color changes outdoor weathered wood

Figure 7. Change in color of outdoor weathered wood. Key O, southern yellow pine , redwood , Douglas-fir and western redcedar.

When wood is exposed to the outdoors or in artificial UV light for a relatively short period, changes in brightness and color are readily observed. The decreases in brightness and color during 480 d of outdoor weathering are shown in Figures 6 and 7, respectively. 

Figure 5. Artis fs rendition of surface color changes during the outdoor weathering process of a typical softwood. Wood initially darkens (yellows or browns) and eventually lightens (grays).

The appearance of wood exposed outdoors without protective paint, stain, or treatment changes markedly in a few months then the wood remains almost unaltered for years (9-11). Color of the wood is affected very early (11,12). Generally, all unprotected woods change in color to a brown. After prolonged weathering, all woods become gray (9). Recent research has been concerned with many aspects of weathering of wood (13-18). 

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