On Monday 30 July 2007 19:30, Derek wrote: > How does one assess the viability of an older plastic > kayak? Plastic can become brittle over time, even if > its stored indoors. Sunlight can make ageing even > worse. How do you determine how much life an older > kayak has left? If you have a kayak infront of you, > how do you determine how brittle it has become? 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. 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! Tord PS A combination of UV and frost kills any plastic, in the long run! The UV cracks the surface, water enter the cracks and the frost does the rest! This combination even kills rocks, eventually! *************************************************************************** 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/ ***************************************************************************
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/ ***************************************************************************
I was pondering this plastic lifespan issue. It seems to me that the "inventors" of this form of plastic would have aggressively tested the material before putting it into production. They should have a pretty good idea what the typical life expectancy is for their product. Does anyone have access to this sort of laboratory data? Derek --------------------------------------------------------------- Please limit all email attachments sent to this address to a maximum of 0.5MB. All email attachments that are larger then 0.5MB will automatically be deleted. --------------------------------------------------------------- ICQ: 262152266, AIM: GlamourpetsD, MSN: [my email address], Yahoo Messenger: glamourpets --------------------------------------------------------------- that gives answers, not web links. http://mobile.yahoo.com/mobileweb/onesearch?refer=1ONXIC *************************************************************************** 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/ ***************************************************************************
On Tue, 31 Jul 2007 08:39:24 -0700 (PDT), Derek wrote: I was pondering this plastic lifespan issue. It seems to me that the "inventors" of this form of plastic would have aggressively tested the material before putting it into production. They should have a pretty good idea what the typical life expectancy is for their product. Does anyone have access to this sort of laboratory data? =============== Considering the product's operating environment it's remarkable that plastic kayaks last as long as they do. The variables are duration and degree of UV exposure, something the maker has little control over. Try googling "polyethylene UV exposure" and you'll get a sense of the difficulty is accurately predicting product life. --allan *************************************************************************** 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/ ***************************************************************************
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