Dave Williams wrote: > Here's a potentially goofy question: what would happen if you put suntan > lotion on a plastic kayak? Would it actually offer some UV protection? Is > it possible that it could harm the plastic? > None of the ingredients in sunscreens should adversely affect polyethylene kayaks. Most sunscreens are formulated in one of two ways - either in an oil base, or in a ethanol base (these are advertised as 'non-greasy'). It would probably be best to use an ethanol-based sunscreen on your boat, as an oil-based one would collect all sorts of grime and grit and make the boat look yucky, and feel even yuckier (think sandpaper). An ethanol based sunscreen will leave a non-greasy film of the UV absorber on the surface as the ethanol carrier evaporates, and the boat won't collect as much grit and grime. In theory, sunscreens should provide some protection, as the active chemical compounds in sunscreens *do* absorb UV radiation. Consider: The SPF factor of sunscreens is a measure of how *many times* longer the average person can stay in the sun without getting burnt. If an unprotected person were in solar radiation that would cause a burn in 20 minutes, then an SPF 15 sunscreen *theoretically* would allow that person to stay in sunlight of the same intensity for 20 x 15 = 300 minutes without showing signs of sunburn. Of course this doesn't factor in individual sensitivities to sunburn or how much sunscreen is worn off the skin or sweated off the skin. I was told several years ago by a sunscreen formulator that the oil-based sunscreens are more effective, as the UV absorbers are more soluble in the oil base and will be more evenly dispersed on the skin than will ethanol-based sunscreens. But I digress. I'd have to agree with the others who suggest that 303 might be more appropriate for boats. Unfortunately, there are no SPF numbers available for 303 as it is not designed for human use - so a direct comparison with sunscreens is not possible. I'd venture a guess, though, that heavier-duty UV absorbers (and probably at higher concentrations) are used in 303, as there are fewer irritation/toxicity concerns as there are for the sunscreen actives that are meant to be applied to human skin. 303 also costs less. Regards, Erik Sprenne *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
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