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Thread: Slowest epoxy?

  1. #1
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    Default Slowest epoxy?

    What's the slowest epoxy? For tedious work I really struggle to use even a minimum batch (2 pumps of resin and 1 hardener) before it's too viscous to penetrate cloth. If I leave that batch in a cup instead of dumping it on a paper plate, it cooks off rock hard and too hot to touch before I can use it. If I put it in a cup and put the cup in a water bath, it lasts about as long as if dumped on a paper plate. Right now I'm using MarinEpoxy with the slow hardener, bought from BoatBuilderCentral. Also, I live in oklahoma and work in a very warm environment. Hopefully winter will be better.

    I read here https://www.epoxyworks.com/index.php...-system-epoxy/ that thinning probably is not a good idea. Any thoughts on that?

  2. #2
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    Default Re: Slowest epoxy?

    Rather than using pumps, consider using a scale to mix it by weight. You'll be able to do smaller batches with less waste. Perhaps that will make you feel less rushed with your epoxy.

    Also, I am leery of thinning epoxy, preferring to follow the instructions on the container.

    Various brands have various speeds of hardener. West has an "extra slow" hardener. Mas might too? I've never used MarinEpoxy. I always use the System Three epoxies, mostly because it's always available where I buy my materials.
    Quote Originally Posted by James McMullen View Post
    Yeadon is right, of course.

  3. #3
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    Default Re: Slowest epoxy?

    west system makes a hardener with a one hour pot life, four hour working time, and twenty four hour cure
    you could extend the potlife by refrigeration

    west help line 866.937.9797


    hardener selection guide: https://www.westsystem.com/hardener-selection-guide/
    Simpler is better, except when complicated looks really cool.

  4. #4
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    Default Re: Slowest epoxy?

    I've had pretty good luck with MAS epoxies. You might check with them or WEST as both have pretty good customer support. I've worked MAS slow in small batches for about a half hour at 80 F. Like you, I spread it out to reduce the thermal mass.

  5. #5
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    Default Re: Slowest epoxy?

    Thanks, I may get some of the west with 209 hardener.

  6. #6
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    Default Re: Slowest epoxy?

    What are you building to generate a scenario where three pumps of resin and hardener goes off before you can saturate a piece of cloth with it? That much resin probably won't do much over a square foot or two of cloth and saturating that shouldn't take more than a couple of minutes.

  7. #7
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    Default Re: Slowest epoxy?

    I'd consider dumping all the mixed epoxy on the cloth you are working, then spreading it around. The more the epoxy is spread out, rather than all gathered together in a mass, the less the heat released by the chemical reactions accelerates the whole kicking off process.

  8. #8
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    Default Re: Slowest epoxy?

    Quote Originally Posted by Random View Post
    …2 pumps of resin and 1 hardener…
    DON’T DO THIS!
    Epoxy is not like polyester resin where more catalyst makes it cure faster.
    Epoxy resin and hardener need to be mixed at a specific ratio. If you get it right, it’ll cure. If you get creative, it’ll either not cure or be weak.

    The better suppliers of boatbuilding epoxies offer very slow hardener. West System 209 ‘tropical’ hardener is one. Note that this needs to be mixed at a different ratio than West System’s regular hardeners and uses different pumps.

    RTFM!
    Last edited by JimConlin; 09-16-2021 at 05:40 PM.

  9. #9
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    Default Re: Slowest epoxy?

    Random,

    DO NOT MIX BRAND NAMES


    MarinEpoxy has 4 speeds of hardener

    i don't even order the fast

    their medium is too fast for this old man

    my normal goto is their SLOW and when working larger sections in the heat i use their TROPICAL SLOW

    the tech i spoke with down there said only the SLOW is even hinted at being blush free

    the rest of their hardeners need to have the blush washed(soapy water and RINSED well) off or nothing else will ever adhear to it(he was right ... i proved it)

    BTW ... i'm 6hours south of you across the Red River and lately i've had tripple digit temps inside my barn w/ mid>high 80% homdiddy and i feel your pain

    a hint for extending your cure time noticeably when laying glass cloth is to simply pour your well stirred mix out on the cloth or surface being glassed and use a plastique body putty squeegie to move it where you want it as well as saturate the cloth easier

    BON CHANCE

    sw
    "we are the people, our parents warned us about" (jb)

    steve

  10. #10
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    Default Re: Slowest epoxy?

    Quote Originally Posted by Todd Bradshaw View Post
    What are you building to generate a scenario where three pumps of resin and hardener goes off before you can saturate a piece of cloth with it? That much resin probably won't do much over a square foot or two of cloth and saturating that shouldn't take more than a couple of minutes.
    Glassing over a small chine log, with fillets on either side, so the cloth has to make relatively tight curves in quick succession. I work slower than most because I'm very much a neophyte, although I did end up developing a technique that worked, and made it so the cloth didn't lift up off the underlying wood.
    Quote Originally Posted by JimConlin View Post
    DONíT DO THIS!
    Epoxy is not like polyester resin where more catalyst makes it cure faster.
    Epoxy resin and hardener need to be mixed at a specific ratio. If you get it right, itíll cure. If you get creative, itíll either not cure or be weak.

    The better suppliers of boatbuilding epoxies offer very slow hardener. West System 209 Ďtropicalí hardener is one. Note that this needs to be mixed at a different ratio than West Systemís regular hardeners and uses different pumps.

    RTFM!
    The pumps are metered pumps that were sold with the epoxy. Going off the markings in a graduated mixing cup, they do in fact work just fine. And yes, don't worry, I'm following the prescribed ratio of resin to hardener.

    Quote Originally Posted by swoody126 View Post
    Random,

    DO NOT MIX BRAND NAMES


    MarinEpoxy has 4 speeds of hardener

    i don't even order the fast

    their medium is too fast for this old man

    my normal goto is their SLOW and when working larger sections in the heat i use their TROPICAL SLOW

    the tech i spoke with down there said only the SLOW is even hinted at being blush free

    the rest of their hardeners need to have the blush washed(soapy water and RINSED well) off or nothing else will ever adhear to it(he was right ... i proved it)

    BTW ... i'm 6hours south of you across the Red River and lately i've had tripple digit temps inside my barn w/ mid>high 80% homdiddy and i feel your pain

    a hint for extending your cure time noticeably when laying glass cloth is to simply pour your well stirred mix out on the cloth or surface being glassed and use a plastique body putty squeegie to move it where you want it as well as saturate the cloth easier

    BON CHANCE

    sw
    I'm not considering using west hardener with marinepoxy resin if that's what you're alluding to.

    Have you had any issue with blush from the slow? I haven't noticed any, but it's possible that I don't know what to look for. It always cures glassy smooth, with no haze at all.

    If I can finish this little boat in time, I'll be taking it to Michigan in a couple of weeks. Should be a nice break from the heat

  11. #11
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    Default Re: Slowest epoxy?

    The issue with blush is not the finish, but getting any other finish to stick to it. The epoxy needs to be thoroughly scrubbed with a scotchbrite pad & lots of water. Has to be water - solvents will not remove it.
    "If it ain't broke, you're not trying." - Red Green

  12. #12
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    Default Re: Slowest epoxy?

    Quote Originally Posted by Paul Pless View Post
    west system makes a hardener with a one hour pot life, four hour working time, and twenty four hour cure
    you could extend the potlife by refrigeration

    west help line 866.937.9797
    hardener selection guide: https://www.westsystem.com/hardener-selection-guide/
    West 209 "extra slow" hardener, if you mix it and pour it out of the container and spread it out you can get several hours of work time. Or find some other way of cooling it. I have used it to pot transducers for installation inside a wooden hull. It takes long enough to cure (overnight at least) that the bubbles will rise to the surface and can be removed permitting a clear solid casting a few inches thick.
    https://www.westsystem.com/the-105-s...slow-hardener/

  13. #13
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    Default

    If you're looking at wetting out glass cloth, you might consider viscosity as well as hardener "speed". And stick with a reputable manufacturer.

    System Three's Silvertip line is designed for 'glass work.

    https://www.systemthree.com/products...ng-epoxy-resin

    https://www.systemthree.com/products/silvertip-hardener

    Low viscosity, 2:1 mix. 2 hardener flavors - slow and fast.
    You would not enjoy Nietzsche, sir. He is fundamentally unsound. ó P.G. Wodehouse (Carry On, Jeeves)

  14. #14
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    Default Re: Slowest epoxy?

    I had good luck using WEST's slow hardener outdoors on a hot summer day on a project that could not be done quickly. I like WEST products because their expertise is quickly available over the phone.

  15. #15
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    Default Re: Slowest epoxy?

    Quote Originally Posted by Random View Post
    Glassing over a small chine log, with fillets on either side, so the cloth has to make relatively tight curves in quick succession.
    Can I ask what sort of boat and construction you're building? That sounds really heavy duty.

    Don't not take steps to mitigate blush. Removal is simple and quick. ALL epoxies will blush under the right atmospheric conditions.

    For small batches you should consider graduated syringes. I have used these extensively for small work and never, ever had a bad batch. Very handy because you can fill them and just dispense the amount you need.

  16. #16
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    Default Re: Slowest epoxy?

    Quote Originally Posted by Dusty Yevsky View Post
    ALL epoxies will blush under the right atmospheric conditions.
    Humidity's the biggie. Carbon dioxide's a player also. Temperature obviously plays a role but in otherwise equal temps if ambient humidity's high it 'encourages' blush.

    And carbon dioxide, which is inescapable under anything but extremely tightly controlled atmospheric conditions.

    Lower humidity and higher temp tends to inhibit it but your 'mileage will vary' depending on which of several products you're using.

    Quote Originally Posted by Dusty Yevsky View Post
    For small batches you should consider graduated syringes. I have used these extensively for small work and never, ever had a bad batch. Very handy because you can fill them and just dispense the amount you need.
    I've gone over to these also for small batches. Two or three ml at a time, mostly for fixing little things or 'potting' fasteners. A double-check is dispensing the components into little plastic cups - specifically the kind you can buy by the thousand for pennies that otherwise would be used to dispense medications in hospitals.

    Be mindful here that volume and density aren't the same thing: if your choice of epoxy's proportions are commonly given in volume, you may need to look into what the proportions are when you're using weight instead.

    Resin and hardener rarely are equal in density so equal volumes of each won't weigh quite the same.

    About amine blush, in probably more detail than you would think possible:

    https://www.epotek.com/docs/en/Relat...ne%20Blush.pdf

    https://www.theresinstore.com/blog/p...oxy-art-resins

    https://www.westsystem.com/instructi...e-preparation/

    The key concept is that amine blush is water-soluble. Sanding alone won't remove it when present, and if you sand first you'll simply push the blush into the texture the sandpaper leaves, making it harder to remove once you get to the water wash down.

  17. #17
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    Default Re: Slowest epoxy?

    Quote Originally Posted by Dusty Yevsky View Post
    Can I ask what sort of boat and construction you're building? That sounds really heavy duty.

    Don't not take steps to mitigate blush. Removal is simple and quick. ALL epoxies will blush under the right atmospheric conditions.

    For small batches you should consider graduated syringes. I have used these extensively for small work and never, ever had a bad batch. Very handy because you can fill them and just dispense the amount you need.
    It is too heavy, and it's not designed this way. It's an elegant punt, but with the chine logs moved inside so that the outsides are cleaner looking. I intended to glass the sole, but only an oval in the middle where you might put your feet. But then I thought how much stronger everything would be if I extended the glass up over the chine and 1.5 inches up the sides. Well it will be strong, but now that I've done it, I'm sure it was quite unnecessary. The large syringe thing sounds like something I should have thought of before, given that hobby epoxy is conveniently sold in them. Thanks, I'll definitely get some.

    Quote Originally Posted by sp_clark View Post
    Humidity's the biggie. Carbon dioxide's a player also. Temperature obviously plays a role but in otherwise equal temps if ambient humidity's high it 'encourages' blush.

    And carbon dioxide, which is inescapable under anything but extremely tightly controlled atmospheric conditions.

    Lower humidity and higher temp tends to inhibit it but your 'mileage will vary' depending on which of several products you're using.



    I've gone over to these also for small batches. Two or three ml at a time, mostly for fixing little things or 'potting' fasteners. A double-check is dispensing the components into little plastic cups - specifically the kind you can buy by the thousand for pennies that otherwise would be used to dispense medications in hospitals.

    Be mindful here that volume and density aren't the same thing: if your choice of epoxy's proportions are commonly given in volume, you may need to look into what the proportions are when you're using weight instead.

    Resin and hardener rarely are equal in density so equal volumes of each won't weigh quite the same.

    About amine blush, in probably more detail than you would think possible:

    https://www.epotek.com/docs/en/Relat...ne%20Blush.pdf

    https://www.theresinstore.com/blog/p...oxy-art-resins

    https://www.westsystem.com/instructi...e-preparation/

    The key concept is that amine blush is water-soluble. Sanding alone won't remove it when present, and if you sand first you'll simply push the blush into the texture the sandpaper leaves, making it harder to remove once you get to the water wash down.
    Well knowing that blush can still occur I will do a wipe down now on everything. If humidity plays a roll, that might be why I haven't noticed any, given that my metal building is a nice even 0% humidity. It's probably not actually zero, but it is very dry and warm. I'm using MarinEpoxy brand with their slow hardener, which are advertised as "Non-blushing", although maybe that just means "Usually not blushing very much". Better safe than sorry tho so I'll wipe things down. I was already wiping everything down with denatured alcohol before epoxy work.

  18. #18
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    Default Re: Slowest epoxy?

    If the ambient temperature is a problem, might try storing it in a refrigerator, and using an ice bucket to keep it cool while working. Used to be a common way to use varnish.

  19. #19
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    Default Re: Slowest epoxy?

    Quote Originally Posted by Random View Post
    What's the slowest epoxy? For tedious work I really struggle to use even a minimum batch (2 pumps of resin and 1 hardener) before it's too viscous to penetrate cloth. If I leave that batch in a cup instead of dumping it on a paper plate, it cooks off rock hard and too hot to touch before I can use it. If I put it in a cup and put the cup in a water bath, it lasts about as long as if dumped on a paper plate. Right now I'm using MarinEpoxy with the slow hardener, bought from BoatBuilderCentral. Also, I live in oklahoma and work in a very warm environment. Hopefully winter will be better.

    I read here https://www.epoxyworks.com/index.php...-system-epoxy/ that thinning probably is not a good idea. Any thoughts on that?
    I use MAS epoxy in the Dallas area all summer long. The slow hardener will kick off pretty quick in a cup in plus 90 degree heat, but I find its just a matter of being prepared. I never use such small amounts when laying cloth as you are, but I have laid both glass and xynole in the heat. I find that once it is stirred up, I dump in out on the cloth as soon as possible and then spread it. Haven't had a problem with it getting too hot before I am done. Vertical surfaces in the heat is a different matter, and I have yet to solve that problem, beyond not mixing any more than I can spread in about 5-10 minutes. So I try to avoid that work in the heat of the summer.

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