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Thread: Epoxy pumps query

  1. #1
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    Default Epoxy pumps query

    I've always poured epoxy resin & activator (International) directly from their original containers and capped them again immediately. All good & they seem to have a long shelf life - though pouring can be messy while the containers are more than half full.

    Now I've been given a couple of pumps to suit which solve the mess issue. But am wondering whether storing them with the pumps installed affects their shelf life. I'd seal the spout with foil or similar but suspect this wouldn't be as airtight as the original screw-on caps. But maybe this doesn't matter much.

    The few googled answers seem ambivalent. Thanks in advance for any words of wisdom from experience.

    Sent from my MI MAX 3 using Tapatalk

  2. #2
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    Default Re: Epoxy pumps query

    pumps yes
    tin foil no

  3. #3
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    Default Re: Epoxy pumps query

    Pumps?

    Yes, but be certain they're calibrated to dispense components at the proper ratios for the products you're using. Not all pumps are created equal.

    Tin foil?

    Certainly not! It's too reactive, likely cause problems with the (usually strongly alkaline) hardeners we're using.

    I use blue (or green, or beige if that's all that's handy) paint masking tape:

    Tear off two or three inches, wipe pump nozzle end with a bit of clean paper towel, seal opening with the middle of the tape bit, then wrap the ends so they seal against each other up & around the nozzle end itself. Fast, easy, inexpensive, and the tab that's left sticking up makes pulling the tape seal off very easy when next you want to do a batch.

  4. #4
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    Default Re: Epoxy pumps query

    Pumps? No, never.

    Mix by weight rather than by volume using a kitchen scale. This method is extremely accurate for small batches.

    No wonky pumps and no iffy calibrated cups to worry about.

    Wiz will be along any second now to disagree.

  5. #5
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    Default Re: Epoxy pumps query

    Lately I've been weighing my batches on a digital kitchen scale. One pump of resin is twenty-five grams and the hardener is five grams. I use the pumps to dispense the liquid as it's a handy and clean method. The routine is to zero out the scale with the container weight, fill the container with the desired amount of resin, and then pump in the hardened with the container on the scale until the proper weight is achieved.


    As for the resin going bad with the pumps installed, I've never worried about it.

    My pet peeve with the pumps is that if you buy the pumps for a five gallon jug you actually get the same pumps that are used for the one gallon and the tube supplied stops about four inches from the bottom. I solved the problem years ago with a length of copper tubing, but it's a mess to change over to a new set of pumps. It's a mystery to me why the proper length tube is not suppled, and probably never will be.

  6. #6
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    Default Re: Epoxy pumps query

    Quote Originally Posted by TerryLL View Post
    .......Wiz will be along any second now to disagree.
    Erm......

    Quote Originally Posted by wizbang 13 View Post
    pumps yes......

  7. #7
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    Default Re: Epoxy pumps query

    Weight works too. Check w/ brand's tech support data to get proper proportions. By weight, ratio's often aren't quite the same as when using volume 'cause the densities of the components aren't aways the same.

    I use weight when mixing teensy bits for things smallish. Scale measures milligrams, components dispensed from plastic syringes into those little plastic dosing cups. Have yet to see a batch fail to cure properly.

  8. #8
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Jim Ledger View Post
    ... a length of copper tubing....
    Copper? In resin maybe, but in hardener?

    I'd think that'd have some contamination potential.

    Polyethylene tubing, of an appropriate size, is readily available in most hardware stores in the US. Easy job of it buying a length to suit your needs for 'long enough' for not much money.

  9. #9
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    Default Re: Epoxy pumps query

    I've been wanting to try the scale method.
    Does anyone have a link for a good digital scale for small batches?

  10. #10
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Eric Moore View Post
    I've been wanting to try the scale method.
    Does anyone have a link for a good digital scale for small batches?
    Trick here is finding one that measures in small enough increments to be useful for truly small batches.

    I bought a battery-powered digital kitchen scale thinking it'd be no great loss if it got stickied up with stuff but despite its capability to measure grams it's not sensitive enough (for my trust) to react quickly as I meter out components.

    Hence my use of a digital scale I used to use for reloading competition ammunition, which measures in milligrams and is thoroughly accurate as well as sensitive enough for either purpose. Wife also uses it to weigh skeins of yarn she knits with so she knows how much (length) is left.

  11. #11
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    Default Re: Epoxy pumps query

    I've been using the OXO Good Grips. It measures in grams or ounces up to 11 pounds (1kg). I looked it up on Amazon and noticed the price has about doubled since I bought mine.

    Screen Shot 2021-10-23 at 5.51.43 AM.jpg

    A serious brain fart by me this morning before I had a second cup. 11 pounds is 5kg, not 1kg.
    Last edited by TerryLL; 10-23-2021 at 11:37 AM.

  12. #12
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    Default Re: Epoxy pumps query

    That's the scale I have, Terry, paid about twenty bucks a few years back. I don't like it for small batches, though because it's not that sensitive and only reads whole grams.

  13. #13
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    Default Re: Epoxy pumps query

    Quote Originally Posted by TerryLL View Post
    I looked it up on Amazon and noticed the price has about doubled since I bought mine.
    Yah that's that 'busted supply chain' thing again showing its ugly head, like its partner inflation.

    This is essentially the one I bought thinking it would be adequate for epoxy mixing. Mine's a different brand but I bet they share internals with a different housing on top.

    It's not. Needs more accuracy.

    Like maybe this one (spendy) or this'n for a lot less money.

  14. #14
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Jim Ledger View Post
    That's the scale I have, Terry, paid about twenty bucks a few years back. I don't like it for small batches, though because it's not that sensitive and only reads whole grams.
    'zactly the point I was making.

  15. #15
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    Default Re: Epoxy pumps query

    What is a small batch ?
    What does one do with 3 drops of glue?

  16. #16
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    Default Re: Epoxy pumps query

    I've done by weight (no go/go on beam grocery scale), volume marked by tape, and pumps. Epoxy is not so fussy that you can't be a % off. I used to attempt to seal pumps (clear plastic held by rubber band) but found with experience no seal needed. As the epoxy settles back in the pump tube it forms its own seal. Next use a few half pumps to clear the air leaves all good in the pump. So, pumps work best.

  17. #17
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    Default Re: Epoxy pumps query

    Quote Originally Posted by wizbang 13 View Post
    What is a small batch ?
    What does one do with 3 drops of glue?
    Last week I mixed up maybe 4cc max. to glue a broken plastic stool top back together for a friend. Used G-Flex. Stuff's pricey, didn't want to haul the whole kit over to her house so I dispensed enough of each into two of those plastic medicine cups I mentioned, sealed with masking tape.

    I ended up using maybe a bit more than half the batch (avoid squeeze-out where possible). This stuff doesn't come with pumps either in the quantity I can afford so I weight it from the squeeze bottles it comes in.

    I need less than that I reach for the JB Weld stuff.

  18. #18
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    Default Re: Epoxy pumps query

    I haven’t had a problem with shelf life of epoxy or hardener. The hardeners darken over time but still work.

    Some pumps will drain back if left for a while. I make sure they’re fully primed before use by pushing gently. If they’ve drained back and are full of air, a gentle push will move them.

    The west System pumps come with a plastic extension tube for bigger jugs. Some other makers’ pumps do, too.

    I use a kitchen scale, but only for larger batches where pumping would be tedious. I don’t use them for small batches because their resolution is, at best, 1 gram. Consequently, if they show 1 gram, that means there’s somewhere between 0.5 and 1.5 grams in the cup, so when adding 5 grams of resin (really 4.5 to 5.5), your hardener percentage is anywhere between 9% (0.5/4.5) and 33% (1.5/4.5). VERY imprecise.

    When using a scale to measure larger batches, I weigh out the hardener first, then the resin, determining the amount of resin I pour as a multiple of the amount of hardener actually poured. Suppose I want a 600 g. batch of mixed epoxy. I’ll first try to pour 100 g. of hardener. It’s an imprecise operation and suppose I actually get 110 g. To have the right ratio of resin to hardener I want 550 g. of resin, so I pour resin into the pot to bring the total weight of the batch to 660 g. Better to have a bit more epoxy than planned than an off-ratio batch of the right size.

    We talk about the mix ratios of epoxy systems in round numbers like 5:1 or 2:1 . The resins and hardeners have different specific gravities, so the mix ratio by weight for West System 105/206, nominally a 5:1 system, is 5.36:1, so the target weight for the batch described above would be 6.36 (5.36+1) times the actual amount of hardener.

    My last (known) off-ratio batch of epoxy was 200 gallons and twenty years back.

    But I digress….
    Last edited by JimConlin; 10-23-2021 at 08:48 AM.

  19. #19
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Eric Moore View Post
    I've been wanting to try the scale method.
    Does anyone have a link for a good digital scale for small batches?
    https://www.amazon.com/American-Weigh-Scales-Signature-Precision/dp/B002SC3LLS/

    Has worked for me. .1g is “good enough”, I simply don’t have the patience to care about hundredths of a gram when mixing Epoxy. I have pumps, use them to dispense into containers that are weighed on the scale.
    Last edited by Hugh Conway; 10-23-2021 at 09:36 AM.

  20. #20
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    Default Re: Epoxy pumps query

    I use the pumps, I store them as they are, the epoxy works.

  21. #21
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    Default Re: Epoxy pumps query

    Have always found pumps to be a PIA, the graduated automotive paint mixing cups that come in various sizes are my preference. Professional auto painters are mixing precise amounts and probably out-number the number of average boat builders mixing of 2 part mixes by a large margin. Second choice would mixing by weight with an accurate scale.

  22. #22
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    Default Re: Epoxy pumps query

    I've been using pumps on WEST Epoxy since the 1970s and have never had a batch that didn't harden or had a problem just leaving them in the cans uncovered. The only thing I do is put them on something non-important, just in case they drip.

  23. #23
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Todd Bradshaw View Post
    I've been using pumps on WEST Epoxy since the 1970s and have never had a batch that didn't harden or had a problem just leaving them in the cans uncovered. The only thing I do is put them on something non-important, just in case they drip.
    ditto
    hundreds of gallons

  24. #24
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    Default Re: Epoxy pumps query

    For measure by weight aficionados, I use a Postal Scale, made by Measurement Ltd., Inc., sparingly as I find container or pump alternatives much more convenient. My feeling is that too much emphasis is directed measuring epoxy. I've been using epoxy since the early 60's when the term appeared in the National Fisherman advocating its use by John Gardner, and have mostly used containers to measure and over five builds, much repair work had only one failure, I forgot to add the hardener. Granted mixing really small quantities should require weighing....however I avoid such small batches accepting the cost of overmixing as a price for convenience. So size of batch and ratio of hardener to epoxy are also considerations for effective mixing. High ratio mixes, West 5:1, require more attention to mixing than say Mas 2:1 mix. The margin of error for high ratio mixes is much higher that the lower ones. So, mostly I use Mas. And of course in large batches less than prefect mix ratios are more forgiving. It would be interesting to learn just how many epoxy failures direct result from improper mixing ratio as compared to time spent mixing, room temperature, and proper pre of area to be epoxied.

  25. #25
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    Default Re: Epoxy pumps query

    Bernd Kohler has plans for an easy, quick and accurate homemade balance.

    _Epoxybalance.pdf (duckworks.s3.amazonaws.com)
    ​​♦ During times of universal deceit, telling the truth becomes a revolutionary act
    ♦ The further a society drifts from truth the more it will hate those who speak it
    ♦ If liberty means anything at all, it means the right to tell people what they do not want to hear
    ♦ George Orwell

  26. #26
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    Default Re: Epoxy pumps query

    If my West cans and pumps are stiff, I just float the cans with pumps attached in a bucket of hot water for half hour or so and they loosen right up and work fine.

  27. #27
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    Default Re: Epoxy pumps query

    I just ordered an american wiegh lb3000 from amazon. .1gm to 3KG And it comes with an optional AC cord.
    About $36 bucks.
    With System 3 pumps, the smalest amount I can make is 3 oz.
    A waste of material for little 1 ounce type jobs

  28. #28
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    Default Re: Epoxy pumps query

    for something like >one oz., just count drops of epoxy/resin( I like using ketchup/mustard dispensing bottles with the lil caps, and use dollartree condiment cups to mix in).........larger, quantities, by weight using a electronic kitchen scale....for A big project I like making a balance scale,- and toss it after the big lay up is over I don't like the hand pumps, they turn into a mess in short order, and are problematic to store
    Last edited by the_gr8t_waldo; 10-23-2021 at 06:17 PM.

  29. #29
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    Default Re: Epoxy pumps query

    I never had a good sense of confidence in pumps (despite the good experience of a slew of folks). I always worried that air got in the system or that things were thicker on cold days. I have a lot of confidence in the accuracy of my inexpensive kitchen scale. I can weigh a dime to check it at its lower end.

    Mixing West System with its 1:5 ratio is, indeed, dicey in small amounts. Nevertheless I have not had any "bad" epoxy mixes. I try to use 2gm:12gm as my lower limit of comfort. 14 grams may be more than I need. I can usually find some other minor job so I can waste less.

    A nice thing about scales is the ability to use the same equipment to mix large and small volumes.

    Tip: When I have used System III, I made sure to look up the ratios by weight. They differ between products. They are not easy numbers for me (like 44:100). I made a table for each product. Once I decide how much I need, I only have to glance at the table. No chance for me to mess up the ratio.

    Scales also give me more confidence in gel type mixes (I like system III Gel Magic). Hard for me to estimate the volume of a blob of resin or hardener. With a scale, I'm sure I got a good mix.

    Obviously, both systems work. Use the one which gives you the most confidence.


    F

  30. #30
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    Default Re: Epoxy pumps query

    I use syringes for smaller batches.

    epoxy-syringe-20ml.jpg


    https://www.fyneboatkits.co.uk/suppl...epoxy-syringe/

    Decant the amount of epoxy and hardener you are likely to use in the next weeks into separate used
    plastic vitamin bottles so the original containers are rarely opened.
    Separate syringe for each. The syringes can last weeks and cost pennies/cents.
    I wrap the syringes in sellotape to protect the markings as they tend to get dissolved or smeared.

  31. #31
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    Default Re: Epoxy pumps query

    I mix small amounts of epoxy by weight all the time for little jobs. We have a spread sheet with the gear that has mixing ratios for each gram of base up to a couple "pumps". When I do need a full pump I still use the scale as it's a great "calibration" or confidence builder that the pump ratios are still metering correctly. We have a 200gram digital pocket scale that we purchased for this use.

    Cheers,
    Mark

  32. #32
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    Default Re: Epoxy pumps query

    Excellent!Thanks for posting that about the syringes.

  33. #33
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    Default

    And from this OP, thanks to all posters for the information; on the basis of the assurances, I have fitted the pumps.

    I just have to hope now that you're not all having a giant lend of me :-))


    Sent from my MI MAX 3 using Tapatalk

  34. #34
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Jim Ledger View Post
    Lately I've been weighing my batches on a digital kitchen scale. One pump of resin is twenty-five grams and the hardener is five grams. I use the pumps to dispense the liquid as it's a handy and clean method. The routine is to zero out the scale with the container weight, fill the container with the desired amount of resin, and then pump in the hardened with the container on the scale until the proper weight is achieved.


    As for the resin going bad with the pumps installed, I've never worried about it.

    My pet peeve with the pumps is that if you buy the pumps for a five gallon jug you actually get the same pumps that are used for the one gallon and the tube supplied stops about four inches from the bottom. I solved the problem years ago with a length of copper tubing, but it's a mess to change over to a new set of pumps. It's a mystery to me why the proper length tube is not suppled, and probably never will be.
    Just a point. The mix ratios quoted by many suppliers of epoxy are by volume. By weight, the ratios are sometimes slightly different, read the literature on the brand that you're using before you go to weight rather than volume.

    Me, never had a problem with the pumps supplied by either Epiglass or WEST. Ive been using them since the 1970s, have built ( think, I've sort of lost count) around 35 boats with them.

    John Welsford
    An expert is but a beginner with experience.

  35. #35
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    Default Re: Epoxy pumps query

    Quote Originally Posted by john welsford View Post
    Just a point. The mix ratios quoted by many suppliers of epoxy are by volume. By weight, the ratios are sometimes slightly different, read the literature on the brand that you're using before you go to weight rather than volume.

    Me, never had a problem with the pumps supplied by either Epiglass or WEST. Ive been using them since the 1970s, have built ( think, I've sort of lost count) around 35 boats with them.

    John Welsford
    I've also been using WEST since the 1970's and I've never had a bad mix – various high-capacity pumps, mini-pumps, volume, weight. Nowadays, I tend to use mini-pumps for larger quantities and weight (simple scale measuring grams) for smaller quantities. That's over 40 years of mixing WEST!! And building boats from 30' up to 50' and many many other non-boat projects in between! And I truly can't remember a failure .... Cheers -- George
    To be truly free to live, one must be free to think and speak.

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