LU-8027 - Correlating Lab & Natural for Sealants

Short wave UV light is responsible for much of the damage to sealants exposed outdoors. Moisture also causes damage, and there often is a synergistic effect between UV and moisture. Experience has shown that materials resistant to UV alone or to moisture alone often fail when exposed to UV and moisture in combination. A third consideration is temperature. Temperature accelerates the rate of any chemical reaction, and while most photochemical reactions are not temperature sensitive, any subsequent chain reactions usually are temperature dependent. Because outdoor exposures are time consuming and the weather is variable from year to year and place to place, accelerated laboratory weathering testers are widely used for research and development, quality control, and material certification.

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