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 Post subject: Shelf life of resin
PostPosted: July 30th, 2005, 10:27 am 
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I was looking at this auction http://cgi.ebay.com/ebaymotors/ws/eBayI ... BIN_Stores

It mentions that it has a shelf life of at least a year. I hadn't ever thought of shelf life with resin actualy. Does it go bad at all?

The price savings of buying in bulk is rather impressive but a kit like that would probably last me several years so it would be a waist to bother unless I know it will still be good that long.

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PostPosted: July 30th, 2005, 11:31 am 
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I have read epoxy resins have an unlimited shelf life. A year isn't an exaggeration. Crystals may form in the resin but you boil water and soak the jug until they disolve.

He does have other "auctions" of lesser quantities. But at tyhoseprices I believe US Compositesare less expensive.

http://www.shopmaninc.com/epoxy.html

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PostPosted: July 31st, 2005, 6:05 am 
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I have used epoxies that were over four years old (see jjoven's post about crystals) and they seemed to work just fine. Did not test for physicals though.

This includes epoxies from System Three, West, Fuller and Ciba - Giegy.

In any case, you should try them out before starting a big project just to be sure they work. I would check the cure time of a sample just to be safe. If it doesn't cure at the proper rate you should be suspicious.

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 Post subject: re
PostPosted: July 31st, 2005, 7:48 am 
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Well I know my Silver Tip is now about 2 years old. The last time I used it I think was spring to seal the twarts and seats. It was giving me problems... it seemed to sheet off the wood in spots but resin isn't designed to be painted on anyway. I don't think it had any crystals.

In any event the shop has probably been 120 degrees this last week (if not more) I will probably mess with some of it soon and keep an eye on it.

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 Post subject:
PostPosted: July 31st, 2005, 10:38 am 
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I've used a number of different brands of epoxy over the years and some seem to store better than others. They aren't all the same and have quite different characteristics.

FWIW it's best to store them in a constant temp range (when possible). I have seen epoxy freeze and still cure after it was thawed back to liquid and also seen heavily crystalized epoxy that only partly cured (don't ask, it was messy ! :doh: )

Most will come with storage recomendations, stick as close as possible to them and they should be good for a long time.


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 Post subject:
PostPosted: August 11th, 2005, 11:39 am 
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Location: Barrie, Ontario
Short answer: For the most part, epoxy resin has a very good shelf life - as others have suggested.


Longer answer: Epoxy hardener may be more sensitive depending on its specific chemisty. It will change colour as it ages and absorbs moisture, but for boat building purposes this is unlikely to cause a significant problem.
I've seen tested physicals diminish as much as 20%, but this takes into account fully post cured test samples that would have had higher properties than most people achieve at home anyway.
FWIW, epoxies containing reactive diluents (thinning agents) and those with heavily phenol based hardeners tend to show the greatest degredation.

As was stated above, crystalization is a bigger problem, a little heat fixes this handily. Keep resin containers well sealed, as contamination can exacerbate the crystalizing tendancy of resin.


Aaron


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