Clean and convenient epoxy dispensing solutions for tiny batches?

Discussion in 'Materials' started by laukejas, May 6, 2024.

?

Which of the methods I described here do you use?

  1. Plastic bottles

    33.3%
  2. Wine bottles

    0 vote(s)
    0.0%
  3. Pump dispensers (please specify)

    66.7%
  4. Syringes

    0 vote(s)
    0.0%
  5. Other (please specify)

    66.7%
Multiple votes are allowed.
  1. laukejas
    Joined: Feb 2012
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    laukejas Senior Member

    I've been working with epoxy for many years now, and I've yet to find a convenient way to dispense epoxy and hardener from whatever container they are in, without having to clean the containers afterwards. This is especially true when mixing up tiny batches (5-10 grams). I do everything on microgram scales (0.1g), with proper mixing and transfer to second cup, and all is well, but I just hate how much mess I get and how many consumables (gloves and paper towels) I need to use there just for transferring components from containers into the cup. I tried:

    1) Plastic bottles - worst of all, since epoxy/hardener gets onto the cap threads, requires difficult cleanup, and eventually the cap jams.
    2) Wine bottles - better than regular plastic bottles, since they have a bulging lip, which prevents epoxy/hardener from running down the outside of the neck, lessening the surface area to clean, also cork is less likely to jam than a cap. Still, no way to pour it out without at least a few drops on the neck, requiring paper towels to clean.
    3) Hand soap / lotion pump dispensers - these should be great in theory, except that they don't allow dispensing few milliliters at a time - they always shoot out an indeterminate amount, which is fine for big batches, but not really usable to get a precise 0.2g drop to get that perfect ratio. And they also clog, especially with hardener, which likes to form crust with air exposure.
    4) Disposable / semi disposable syringes - good for accuracy, but require cleaning or soaking in acetone, which ends up with even more mess. Also not economical in the long run.

    I know West System sell some of their epoxies in containers with calibrated dispensers, but these are also meant for bigger batches, they don't allow pumping out a small and custom amount. I checked with my epoxy supplier, and they don't have anything either.

    Surely someone has found a better solution? Something that allows to get small, precise amounts of epoxy and hardener out of containers without any cleanup necessary, that doesn't eventually clog the system?
     
  2. kapnD
    Joined: Jan 2003
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    kapnD Senior Member

    Try Google search of “proportioning dispensers”
     
  3. fallguy
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    fallguy Senior Member

  4. laukejas
    Joined: Feb 2012
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    laukejas Senior Member

    You mean devices like this one? https://bluemulecleaning.com/wp-content/uploads/2020/01/BLU81_Illustration.jpg I searched around, and they all seem to be meant for much larger batches... Certainly not designed to pump out few grams at a time. Or am I looking at the wrong thing?

    I don't quite understand, are you suggesting to store epoxy in these medical cups? Or did you mean to use them for mixing? Perhaps you misunderstood me, mixing is no the issue, it's transferring epoxy components from their main containers into the mixing cup without having to do a clean-up afterwards... Can you clarify what you meant? I feel like I missed something.

    You mentioned the WS pumps, I did address them in my post - perhaps I am mistaken? Do they actually allow pumping out fractions of grams at a time? Suppose I need to make a 10g epoxy batch, it has ratio of 100:30, so I'd need 7.7g of epoxy and 2.3g of hardener. Would WS pumps allow me to dispense components from their containers into the mixing cup with such accuracy?
     
  5. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Buy yourself two glass syringes, either the old glass/metal type from the soviet times, or the new all glass from a laboratory supply house, they are reusable forever. Luer taper not the locking type. Then take some soft rubber and make yourself a cap for the tip (drill matching tapered hole), label the syringes and caps (paint, permanent marker, etc). Preload, wipe the tip and put on the cap, the epoxy can stay in there forever ready to use (keep them in a padded box, that will protect the syringes from breaking and the epoxy from sunlight). No cleaning with acetone involved as long as you don't accidentally switch the caps, dip the resin syringe in hardener (or vice versa), just wipe the tip with a clean piece of paper and put the cap back on.
     
  6. laukejas
    Joined: Feb 2012
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    laukejas Senior Member

    I initially dismissed syringes because I thought they'd have to be refilled for every use, but perhaps if I get some big ones (300-500ml), that would not be necessary, and refilling can be done with a tube, so I can still refill from original epoxy containers that have narrow openings. So yeah, this is a decent idea. Having to clean the tip with piece of paper still sucks, but it's better than nothing. Why glass syringes instead of plastic, though? Glass ones are incredibly expensive, especially big ones (I'd need that to avoid frequent refilling), and they are so easy to break. If a plastic syringe doesn't get melted by the hardener, then it should be fine, no?
     
  7. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    I tought you don't like plastic ones for some reason, that's why I said glass. Plastic is actually fine, but even glass ones don't need to be expensive, it doesn't have to be Schott.

    Best time to fill syringes is when you have a bigger job, pour the resin and hardener in separate cups, fill the syringes and use the rest for the job. As long as you have a good cap on them the epoxy won't go bad, it doesn't in the original bottle either. Even a crappy cap will do the job, the hardware store epoxy that comes prepackaged in syringes survives just fine after opening.
    As long as you work cleanly, don't mix up the caps, don't submerge the syringe tip when dispensing and there is very little cleanup involved, mainly the tip when refilling, and the occasional drop after dispensing.

    If you do this kind of very small jobs often, probably the best thing to do is to have a set of separate wide mouth containers with a good lid, something like these 120mm wide ones: 300ml Gourmetglas komplett WECK RR120 https://www.weckglaeser.com/shop/weck-komplettglaeser/weck-300ml-gourmetglas.php used just for refilling syringes.
    Pour from the original container into them, then it's easy to fill the syringes without a big mess (only submerge the end of the tip). Whatever remains into the glass stays there, just put the (correct) lid on. As long as everything is clearly labeled so you don't cross contaminate you can use the same container and disposable syringe set basically forever.
    You can use plastic or metal containers if you like, the glass jars in my link are heavy and won't accidentally move around and spill while you refill because you touched the edge with the syringe or the back of your hand, and that's a good feature in my book.
     
  8. skaraborgcraft
    Joined: Dec 2020
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    skaraborgcraft Senior Member

    I have no issue poring resin or hardner from a 5 litre can, for batches of 3gm+. I have used the bottom of a polyethylene bottle for mixing, which can be re-used when any material left in it hardens and can be easily removed. I have never understood the transfer from one mixing cup to another, I have never done it, and never had an epoxy failure. I see the Likes of Yrvind doing it and suggesting it must be done, while he fills up endless black waste bags with plastic cups, and saying small boats are eco-friendly.
     
    fallguy likes this.
  9. fallguy
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    fallguy Senior Member

    I always mix tiny batches into two medicine cups from the main container which is always at least a half gallon. I’ve always hated the mixing mess the most. But if you gear the mixing container toward the batch size it reduces cleanups. An overpour is dealt with by dipping a clean stir stick into the cup. Then I usually pour resin to hardener and oftentimes send it back once.

    The reason I failed to comprehend the question is I’ve never found pouring to be the issue (either). I think my batches are usually too big for this minutae. But the medicine cups are my goto for tiny batch work.
     
  10. laukejas
    Joined: Feb 2012
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    laukejas Senior Member

    I'm okay with plastic syringes now (not against plastic here, just thought there is no way to keep them clean - but your suggestion should work). Good advise on the main containers as well, thank you. As for cross-contamination, I always label everything clearly and double check - never had an incident in over 10 years (had other kinds of incidents instead).

    Bottom of PET bottle, you say? I am actually looking for a solution to replace plastic/paper cups as well, since I hate how environment un-friendly they are. I might try that. What about silicone mixing cups? Shouldn't they make it even easier to remove hardened epoxy, given their natural flexibility? As for pouring from cans, how do you pour so that you avoid having to clean the tip of the can afterwards?
     
  11. skaraborgcraft
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    skaraborgcraft Senior Member

    I see no reason silicone cup would not work.
    The end of both my resin cans have minor dribbles, but i lose more milk from a container in a week than i do in a year of epoxy mixing. Warm resin helps it flow better, or drip it from a mixing stick.
    Epoxy work is heavy on consumables including ppe.
     
  12. fallguy
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    fallguy Senior Member

    Any silicon residue is a nightmare at paint, so I’d do some serious testing before using in boat builds.
     
  13. skaraborgcraft
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    skaraborgcraft Senior Member

    Thats a fair point, we had a WD40 ban inside the garage for exactly that reason. However, given the amount of silicone cooking implements, i would guess they have it sorted, though i probably already have a good amount of silicon and teflon inside me.
     
  14. laukejas
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    laukejas Senior Member

    Are you saying that using silicone mixing cups introduces silicone residue into epoxy? Shouldn't silicone be fully cured and not contaminate anything? Or does it still remain reactive and mess epoxy up?
     

  15. skaraborgcraft
    Joined: Dec 2020
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    skaraborgcraft Senior Member

    That would be my thoughts. Washed out waxed milk cartons can be used too, the top 75% can be recycled and saves on plastic waste.
     
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