Published: Jan 1998
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There are several completed studies of sealants weathering outdoors and in accelerated weathering machines. There is no perfect correlation but there are remarkable similarities in the results and a general correlation is possible. The general conclusion is that it takes no less than 1000 hours in the machine to equal one year in South Florida in the full sun. These are with static samples. It is certain that the user of lab tests and the user of sealant specifications wanting an indicator of long term performance should look with a skeptical eye at durability claims that suggest short times (less than several thousand hours) in weathering machines as adequate. Such short term tests should be regarded with great skepticism and mistrust. The reasonable conclusion is that a 5000 hour or 10,000 hour of artificial weathering exposure followed by many cycles of movement are needed to have a realistic weathering test. The other major conclusion is that durability is sealant specific and broad general claims over entirely generic classes might point to a trend but won't define specific behavior. For specific information the specific sealant of interest, in the color of interest must be studied.
Durability, artificial weathering, accelerated weathering, sealants, ultraviolet, outdoor weathering, joint movement, sealant specifications
scientist, Dow Corning Corp., Auburn, MI