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Thread: Epoxy pumps query

  1. #36
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    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 noticed that also. Since going from volume to weight, the resin tub will empty a bit before the activator. So I'm guessing the cure time would be slightly longer than a perfect volume mix.

    But does this have any consequence for the quality of the finished product? I've not noticed any difference, which makes me wonder just how rubbery these mix numbers might be.


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  2. #37
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    Default Re: Epoxy pumps query

    Quote Originally Posted by wizbang 13 View Post
    ditto
    hundreds of gallons
    Same. never had a problem. I ALWAYS burp the pumps into a scrap can before I start dispensing for the actual mix. If the pumps didnt work, West wouldnt be using them.

  3. #38
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    Default Re: Epoxy pumps query

    I'm the outlier that had a pump go bad. It was while applying fiberglass on the bottom of a 17' boat which took several batches, all of which did not harden. After that all batches were weighed.
    I just bought an epoxy kit with pumps and will use them again.
    ​​♦ 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
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    ♦ George Orwell

  4. #39
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    Default Re: Epoxy pumps query

    Pumps seem to always burp on me, so I pump into two separate containers then mix, just easier to weigh it at that point.

  5. #40
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Autonomous View Post
    I'm the outlier that had a pump go bad. It was while applying fiberglass on the bottom of a 17' boat which took several batches, all of which did not harden. After that all batches were weighed. ....
    Trust me - you ain't no outlier.

    One bad batch on a piece of wood with 20 hours work in it - makes a really bad day.

    Digital scales.
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

  6. #41
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    Default Re: Epoxy pumps query

    I agree with the digital scales recommendation and would add the caution that they need to be verified for accuracy from time to time,not to mention regular battery checks.You may guess why I have this opinion.

  7. #42
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    Default Re: Epoxy pumps query

    I had pumps go bad years ago due to infrequent use, so they went in the trash. I've been mixing by weight ever since with zero problems. I suspect pumps work perfectly fine if used frequently and maintained properly. Bottom line is, whatever works for you, use it. There are several right methods in this debate.

  8. #43
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    Default Re: Epoxy pumps query

    Quote Originally Posted by John Meachen View Post
    I agree with the digital scales recommendation and would add the caution that they need to be verified for accuracy from time to time,not to mention regular battery checks.
    Having some experience in another discipline where scale accuracy's relied upon I have to add that the 'you get what you pay for' axiom holds hard with digital scales. And 'trust but verify' along with.

    All kinds of objects may serve you well as a check weight as long as: 1) you can remember where you last put it and 2) that it doesn't change weight over time.

    Use of such an object serves to tell you what the state of your scale's condition is at the time you employ it.

    What are 'inexpensive' scales (under US $300 as a generality) can be affected by all kinds of electromagnetic disturbances from sunspots to magnetic fluorescent light ballasts in close (sometimes 20 feet may be too close!) proximity to that cell phone you have in your pocket.

    Static electricity's a biggie too, often unnoticed but commonly the single most important factor that will cause irregular readings.

  9. #44
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    Default Re: Epoxy pumps query

    In the '70s when I began with WEST I began with premarked dixi cups - one for hardener and one for resin each aimed the mixing cup. Good enough but better was a produce beam balance where I could move the weight out to where ever and then just pour till the beam tipped. Eventually invested in pumps which are finastkind.

  10. #45
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    Default Re: Epoxy pumps query

    Quote Originally Posted by sp_clark View Post
    What are 'inexpensive' scales (under US $300 as a generality) can be affected by all kinds of electromagnetic disturbances from sunspots to magnetic fluorescent light ballasts in close (sometimes 20 feet may be too close!) proximity to that cell phone you have in your pocket.

    Static electricity's a biggie too, often unnoticed but commonly the single most important factor that will cause irregular readings.
    .............your cutting this, entirely too thin!

  11. #46
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    Default Re: Epoxy pumps query

    pump hot water through the hardener pump
    pump hot vinegar through the resin pump
    they are good for decades

  12. #47
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    Default Re: Epoxy pumps query

    Quote Originally Posted by wizbang 13 View Post
    pump hot water through the hardener pump
    pump hot vinegar through the resin pump
    they are good for decades
    Sounds like a good fix. My pumps could use a go. But what to do with the wash waste?

    Jeff

  13. #48
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    Default Re: Epoxy pumps query

    Quote Originally Posted by sp_clark View Post
    Having some experience in another discipline where scale accuracy's relied upon I have to add that the 'you get what you pay for' axiom holds hard with digital scales. And 'trust but verify' along with.

    All kinds of objects may serve you well as a check weight as long as: 1) you can remember where you last put it and 2) that it doesn't change weight over time.

    Use of such an object serves to tell you what the state of your scale's condition is at the time you employ it.

    What are 'inexpensive' scales (under US $300 as a generality) can be affected by all kinds of electromagnetic disturbances from sunspots to magnetic fluorescent light ballasts in close (sometimes 20 feet may be too close!) proximity to that cell phone you have in your pocket.

    Static electricity's a biggie too, often unnoticed but commonly the single most important factor that will cause irregular readings.
    My wife's electronic kitchen scale (used to be mine...) is close enough for epoxy and cooking. For precise, small weights my experience mirrors yours. Till I figured it out and got a beam scale I thought other components were unreliable.
    ​​♦ 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

  14. #49
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    Default Re: Epoxy pumps query

    The only time I've had trouble with the pumps has been if I let the epoxy get too cold. It crystalizes but you can warm it up and the crystals go back into solution. Just drop the whole jug into a big pot of hot water.

    The System 3 pumps are $7.95, a gallon kit of epoxy plus hardener is about $160.00, buying a fresh set of pumps at the start of a new project is a very small drop in the boat building bucket.
    Steve

    If you would have a good boat, be a good guy when you build her - honest, careful, patient, strong.
    H.A. Calahan

  15. #50
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    What about if I were to suggest, from limited experience, that the dosage numbers need not be all that accurate for the final product to turn out just fine.

    For example, the proper International brand dosage is 3:1. But experimenting with 2.5:1 & 3.5:1 mixes, the only difference appears to be the curing time.

    So unless the quality of the final product varies (and perhaps someone here can assist with that), seems even dodgy $5 Kmart scales are well sufficient.

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  16. #51
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    Default Re: Epoxy pumps query

    Oh, if only it were so simple.
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

  17. #52
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    Default Re: Epoxy pumps query

    An adequate bond can happen with either "too much" or "too little" hardener but as I understand the chemistry it's not close to best bond. Epoxy makes such a good bond that many are happy getting away with imperfection of some degree, often unknown.

  18. #53
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    Default Re: Epoxy pumps query

    Amongst the horrors of an inexact mix are.

    Free Bisphenol-A... https://www.mayoclinic.org/healthy-l...a/faq-20058331

    Free Amines, which can inhibit the cure on subsequent paint or varnish coatings.

    Just get it right.
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

  19. #54
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    Default Re: Epoxy pumps query

    Its pretty easy to check on the accuracy of inexpensive kitchen scales.
    A US nickel weighs 5 grams.
    Water weighs 1 gram per ml.
    One can check accuracy and precision at both the low end and the high end of your working range.

    With a scale, I know that I can mix virtually any size batch I need.

    As an amateur builder (Calendar Islands 18) I mix small quantities in the small yogurt cups. I know that each one weighs roughly 7 grams. This gives me a disposable calibration weight with each batch.

    In addition to using West System for much of my work, I am a fan of System three's "Gel Magic". Weights give me much more confidence in the mix ratio with these gels than volume estimation does.

    One trick for amateurs like me is to save a bit of each batch overnight. Seeing that this sample is hard gives confidence that the prior day's glue-up is proper and will not fail.

  20. #55
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Ian McColgin View Post
    Epoxy makes such a good bond that many are happy getting away with imperfection of some degree, often unknown.
    I think I have probably been guilty of that for very small batches.
    I do find my pedantic self wondering how you got to become aware of an unknown imperfection.
    There is nothing quite as permanent as a good temporary repair.

  21. #56
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    Default Re: Epoxy pumps query

    One rarely becomes aware of an unknown imperfection. One only knows if there's a failure and if the cause of that failure is understood. Unknown unknowns and all that.

  22. #57
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    Default Re: Epoxy pumps query

    Boats can be subject to extreeme stresses,racking and pounding,along with extreeme temperature and humidity changes.
    I can't imagine not following the manufacturers mixing ratios to the best of your ability.
    It's differentif you were gluing together a napkin holder

  23. #58
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    Default Re: Epoxy pumps query

    I think School programs (adult or kid) would be a train wreck using scales. In fact even with pumps I have seen students not let the plunger get all the way back to the top before they start another stroke. For my own boat I bought the West system dual pump where one stroke actuates both pistons because I was going to have some inexperienced help for the high-volume sheathing operations, and a failed batch would have been a huge mess. However, the West dual pump is unfortunately very poorly designed, the reservoirs are cheap, flat-bottomed and don't feed from the lowest point, so if you want to change the pump to a different type of hardener it's a big pain to get the old stuff out. I ended up keeping the dual pump loaded with the "Special Coating" hardener, and using the pump-from-a-can system for other gluing operations. Regarding small batches & gluing small parts, I have tried to keep a couple of those projects pre-fit and laying around the shop ready to use the squeeze-out or left-overs from the bigger stuff.

    Ken

  24. #59
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    Quote Originally Posted by Ian McColgin View Post
    An adequate bond can happen with either "too much" or "too little" hardener but as I understand the chemistry it's not close to best bond. Epoxy makes such a good bond that many are happy getting away with imperfection of some degree, often unknown.
    Thanks Ian, I'd been looking for data or graph showing, hopefully, only a marginal loss of integrity of the final product within a certain range of error, before falling off the cliff. But seems none such exists.

    Never mind, I think I'm usually accurate and it was only idle curiosity anyway. Cheers


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  25. #60
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    Default Re: Epoxy pumps query

    I just want to know why one pump always craps out and the other doesn't, and why west won't sell singles.

  26. #61
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    Because they know the good one will crap out soon enough anyway?

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  27. #62
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    Default Re: Epoxy pumps query

    We had on this Forum and epoxy maker who, without pushing his brand give excellent advice. Also, in the '70s I was introduced to the good goop by two of my former students who'd gone on to be epoxy engineers, making formulation for specific applications.

    The proprietary (brand name) epoxies test mix ratios and additives. Those data are closely held but there are folk, especially in aerospace and such, who have access often because they worked with the company to perfect a really out there application.

    Another route, such as being taken by a boatbuilder friend is to stick with the basic formulation and experiment with resin to fibre content by increasingly strident vacuum bagging. Final panel weight is now well below 1/4 where he started for tested suited strength, flexibility/flex resistance, et cetera. There's a huge community pushing the boundaries but since they don't control the variables they can't just answer how bad being a little sloppy might be.

  28. #63
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    Default Re: Epoxy pumps query

    Quote Originally Posted by Mitziel View Post
    Because they know the good one will crap out soon enough anyway?

    Sent from my MI MAX 3 using Tapatalk
    No, it's double the turnover and double the margin right down the supply chain. That's why.

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