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Thread: Old epoxy

  1. #1
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    Default Old epoxy

    I built my last boat 8,1/2 years ago. Time for another build. I had some left over epoxy from that build. The part A (the one you put in 2 parts when mixing) has a layer of white on the bottom which seems to have stiffened up if not actually hardened. When I turn the bottle sideways, it doesn't appear to be settling like the clear does. Just wondering if this is any good. I was under the impression that epoxy had no expiration date. It was kept for 4 of the last 8 years in an unheated shed so it has been through several winters with freezing temps. It's not really a big deal, but epoxy is expensive; and, if it's any good, I'll use it. If not, I'll toss it.

    epoxy.jpg

  2. #2
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    Default Re: Old epoxy

    I've used WEST that had seen at least three winters and it worked but that's younger than you have and I did not see any settling or separation. The WEST catalyst had reddened with age but was still working. I'd put your old epoxy into the hazardous waste department, like old paint cans.

  3. #3
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    Default Re: Old epoxy

    I've had epoxy go white like that in cold weather. I put the bottle in a pan of hot/warm water, after two or three changes to warm it up again, it returned to normal. I would try that before tossing it. If you're worried, try a test piece before using it on your boat.

    Jamie

  4. #4
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    Default Re: Old epoxy

    I just used old epoxy (8 years old) to glue a carbon fiber strip into a guitar neck.
    I kept the epoxy in an unheated shed ( that's 8 summer/winter cycles )
    The strip is glued rock solid into the wood.
    Drying time was still according spec's ( clamped for 24 hours)

  5. #5
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    May 2015
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    Default Re: Old epoxy

    Quote Originally Posted by Jamie Orr View Post
    I've had epoxy go white like that in cold weather. I put the bottle in a pan of hot/warm water, after two or three changes to warm it up again, it returned to normal. I would try that before tossing it. If you're worried, try a test piece before using it on your boat.

    Jamie

    This - just heat it up & do a test bit. I've 10 year old epoxy - a small bit of System3 fast set - that's I still use & trust. My regular supply of Sys3 resin slowly goes solid below 60degF & every year I have to heat it up till it's clear - Moe

  6. #6
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    Default Re: Old epoxy

    Yes, I've had older cold (below freezing) go whitiish and get better after gentle warming. But it was all even, not like this separation.

  7. #7
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    Default Re: Old epoxy

    It's crystlalization, happens after a while with most epoxies. Happens more with temp variation but I had some MAS doing it to me that was always kept indoors in a spare room and not 'old'. Once it starts crystallising it tends to do it again and it becomes a pain. Looked just like that.

    You can gentle warm it (in a pan of warm water for a while) or leaving it in sunlight on the windowsill is usually enough in summer and it'll go clear again.

    It's well expired, so ideally might not be worth relying on it, though I dare say it would work probably fine. Use it non structurally, or after a test piece.

    I switched to a Sicomin epoxy that specifically won't crystalise (but can blush) because I realised my boatbuilding pace is glatial. They are available but are the exception. I liked MAS though, it was quite flexible when cured which I liked and didn't blush. Don't know what B and B's epoxy is but the mix ratio would narrow it down. 2:1 is the same as MAS Flag resin. CLC also used to use it. There isn't the perfect epoxy yet with all the best features combined.
    Last edited by Edward Pearson; 02-09-2021 at 04:26 PM.

  8. #8
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    Default Re: Old epoxy

    I tend to relegate old epoxy for making filler.Ideally just the sort you might use for filling the weave of cloth sheathing,I would hate to find out the hard way that the bonding qualities had degraded,but a bit of filler falling off would be a minor irritation should it occur.

  9. #9
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    Jul 2020
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    Default Re: Old epoxy

    I had an ancient 5 Litre can of epoxy half used.. It's catalyst has gone from clear to a muddy brown.. That was great for filling a pond on a model railway based in the highlands of Scotland so the water is a peaty brown anyway.
    But used as a resin Glue I found it unreliable, it's setting was very variable, I needed lots of extra heat to get it to set..

    It's replacement can has been all but used up on the boat, just in time to have UK resin prices go up 30% in the last 3 months.. I'm going to get another can to finish.. But do I go for a small or large can? With the price I don't want it to be sat around for years before the next major modifications to the boat..
    Just an amateur bodging away..

  10. #10
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    Default Re: Old epoxy

    I set the jug on a heat register for the night. This morning the bottom is virtually the same. I may do a little test with the remaining liquid portion but doubt I will count on it for major structural components. Thanks for the input.

  11. #11
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    Default Re: Old epoxy

    Once again to note: Boat building and boat maintenance involve handling lots of variously toxic materials. Our cans that once held paints or glues or solvents usually have at least some residue or, like the OP, a fair amount of now unusable left-over. This is hazardous waste that should not go into the general headed for the land fill garbage stream.

    Unfortunately, many towns only accept such hazardous materials once a year. I am very lucky in that First Light lets me put my old paint, glue, and glop pots in with theirs. If you're working from home, you may need a place to set such things aside and stay alert to your town's hazardous waste day.

  12. #12
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    Default Re: Old epoxy

    I'd always been told that the resin or base component of epoxys and polyesters are always slowly hardening, the addition of the catalyst just speeds the process. I have a couple of kilos of a polyester car filler, maybe five years old that now has the consistency of thick toffee when it used to be like non-runny honey. it still works but its a pain to get the catalyst mixed in. and its harder to use as its not so spreadable. Does work though , so gets used like a thick pug for filling or making up deep or large areas. Filler though, and not strictly epoxy maybe.
    If my eyes don't deceive me, there's something going on around here

  13. #13
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    Default Re: Old epoxy

    The styrene evaporates out of polyester based fillers,given the chance.Which means it happens a little each time you take the lid off.This is in addition to the very slow polymerisation that goes on in the background.You can stir a little more resin in to make it a bit more spreadable.

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