Tord Eriksson wrote: > Immersing nylon screws in boiling water recovers their strength > quite a bit - all plastics need to have a certain amount of humidity > in them, to attain maximum strength. True for nylon (and, perhaps, Dacron) -- because of the polarity of the groups formed when it is manufactured (nylon is a polyamide; Dacron is polyethylene terephthalate, a polyester), which are attracted to water; other, nonpolar plastics such as polyethylene and polypropylene need refreshing of their plasticizers (small, nonpolar molecules incorporated into the polymer mix at manufacture) to maintain their plasticity and avoid embrittlement. The differing chemical makeup of plastics accounts for these differences. Not all plastics are chemically alike. > I would think washing the plastic kayak in fresh water, once in a while, > is one way of keeping them OK - a sunblocker, like 303 Aerospace, > can be used to block the UV, or you could paint it with a 'silver' colour, > totally blocking light reaching the surface! Washing only keeps the surface clean -- it does not extend the life of the boat; however, 303 contains a common placticizer, and slows the aging process of rotomolded boats. It also has a UV absorber. Finally, some paints have solvents in them which may prematurely age rotomolded boats ... and most paints will not stick to such boats anyway. Exception: Krylon's Fusion does stick to polyethylene. Sorry, Tord, but these false rumors need to be spiked aborning. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Tue Jul 31 2007 - 06:55:20 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:31:25 PDT