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. fallguy
    Joined: Dec 2016
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    fallguy Boat Builder

    I said test it. The silicon release agent on Sherwin Williams plastic paint trays contaminated my paint job; took me a few weeks to realize the source. Imagine my horror painting and always getting fisheyes, no matter how clean. The release agents on tinfoil are not silicon….
     
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  2. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    What kind of paint? Had exactly that problem before the wd40 ban with enamels. There are special wipe down rags for cleaning silicone contamination, but it is best to avoid it in the first place.
    Theres no end of silicone mixing sets for epoxy, used by artists, so i do wonder if there is a paint issue outside of plain resin casting.
     
  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You should have a big sign indicating that silicone is banned from the shop. It contaminates everything and is really hard to fix later. Try rubbing your fingers on cured silicone caulk and you will feel they are slippery.
     
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  4. rxcomposite
    Joined: Jan 2005
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    rxcomposite Senior Member

    We use untreated/unwaxed paper cups for mixing. Silicon/silicon wax is banned in the workshop. We use prepreg and high temperature curing so any traces of silicon will cause "silicon migration" during curing. While there are solvents to rid these silicon contamination, you do not see the silicon so it is best if it is not existent in the shop. There was a study/article written in a popular aviation magazine confirming this.
     
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  5. rxcomposite
    Joined: Jan 2005
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    Location: Philippines

    rxcomposite Senior Member

    We use a simple homemade wooden balancing scale. Since part A and B are of different densities, one end is biased towards the center. Later we used this calibrated auto dispenser. The problem is the Buna O ring will fail after some time so every start of shift, the QC will dispense a small calibrated amount to a paper cup, mix well and time the gelation time. A small price to pay for Quality Assurance since we are on mass production.
     
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  6. TeddyDiver
    Joined: Dec 2007
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    Location: Finland/Norway

    TeddyDiver Gollywobbler

    I tried once one brand with weight ratio, never again. WS pumps are so easy, fast and tidy to use.. That said I always have something to smear the leftovers to..
     
  7. laukejas
    Joined: Feb 2012
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    Location: Lithuania

    laukejas Senior Member

    This is really surprising, seems quite weird that silicone is so impossible to clean before using it with epoxy so you'd rather ban it from the shop entirely. Unfortunately I ordered a few silicone mixing cups from Ali, so I guess I will test them to see if they give off any residue or not, and if perhaps it is possible to clean them to the point where they'd give off no more residue and be safe to use with epoxy. Apart from rubbing fingers after touching them, what is the best way to test if they contaminate epoxy? If they somewhat reduce epoxy binding strength, it might be quite difficult to determine.
     
  8. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    The contamination will show when you paint and get fish eyes and/or peeling.
     
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  9. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    Leave a mix to go off in the pots, then paint it. If you get fish eyes, then it will also mean silicone in your bonding epoxy. It should not make any difference for the strength of a fillet and tape/glass adhesion, but does mess up a paint finish.
     
  10. seasquirt
    Joined: Dec 2015
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    Location: South Australia

    seasquirt Senior Member

    Hi laukejas, I think I know what you want. I sometimes use a small plastic bag, or several in fact, sandwich bag, freezer bag, whatever is clean and tidy, not too thin, with a secure welded/melted seam, trim the excess plastic past the seam off the corner, then dispense a bit of part A or B into it (not both), work resin into the corner, twist the rest of the bag up loosely, so it's not under pressure, make a pin hole in the corner of the bag, and dispense like using an icing bag. If making micro batches, drag a smear / line of part A, on alfoil laid on the scales, measure, zero, calculate, and then an appropriate quantity smear or line of part B alongside away from it, so the part B's bag isn't contaminated, measure, adjust, then mix on the alfoil. Keep the plastic bags well separated and they will last days, or hours anyway. They fail with thickened mixes though. I do micro epoxy mixes by eye and rarely had failures, mixed with a sliver of wood popsicle stick on the alfoil.

    To charge the plastic bag corners, I lay out 4 or so pieces of toilet paper, cheap as; having first pre-warmed the resin parts A and B in the sun, tip an estimated amount in the bag corner, (or even put the bag corner over the container and scoop a bit in from the outside), wipe drips off container with a piece of TP, and discard TP, PUT THE LID ON bottle and put it out of reach on the work bench, then another piece of TP for part B when dispensed similarly into another bag, and discard, lid on bottle, put it out of reach too, same again if TPRDA or other additives are being used. Be carefull with runny additives after handling / waiting patiently for gloopy resins to ooze out of their bottle, or drum.

    Small mixes I lay cling wrap over scales, trimmed to avoid false readings, TP square on top, mix container on that, and same process, zero, dripping / pouring into the mix container, wipe bottle neck, lid on, then out of reach so you don't stuff up, as I have in the past. Next part measured on top of first, then when all is tidy, and capped, mix the two, or three parts.

    Mixing containers, Never use glass; have used: small seafood tins, bottom of plastic milk bottles and juice bottles, alfoil flat or dished, and my favourite, a waxed cardboard dressing container from a 1970's Kentucky Fried Chicken dinner, which has seen many hundreds of small mixes since then, of several different resins, (the Colonel would be impressed). Popsicle sticks to mix small batches, used edge on when mixing stiff filler, an X marked on one end both sides of the stick, to hold the dry end; old toothbrushes with a bent neck (via cig. lighter) for wetting out; and a 3/4 inch wide steel scraper / spatula for scraping out mix containers and shaping thickened resins. When done, scrape out the residue, and final clean with a rag, then it's ready for next time. Or immediately if I have time for another small mix.

    Nearly everything gets re-used, only excess or old resin gets discarded. I usually line up 2 or 3 other small jobs ready to do, in case I do get excess, and a crappy non structural filler job for half gelled drips and scrapings on cleanup at the end.
    I've never done big batches more than 3 litres at a time, and rarely had heat problems.
    I hope this helps someone.
     
  11. Jason Rodgers
    Joined: Mar 2021
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    Location: Cruising

    Jason Rodgers Junior Member

    I use West's and also weigh all batches and faced the same problems. My solution for small batches and reduced mess and waste is to use out of the box tongue depressors: 1 marked with a blue coloured "R" (Resin), and 1 marked with a red coloured "H" (Hardener) at the very ends where you will hold em. You will find that you will become good at dipping in the depressor stick and dispenssing in even the smallest of cups without a drip on the scale, knowing how much dip to dispense a certain weight and how many drops will get your number (e.g. 5.36 scale values switch between 5.3 and 5.4). The only risk here is to mix up the resin stick with the hardener stick. To avoid this I cut half stick sized paper towel to wrap each dispenser stick at the wet end while in use and always place each stick in front of the correct West's container between use, ensuring the resin and hardener containers are kept well apart on opposite sides of the scales.
     

  12. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Boat Builder

    mix a batch of epoxy in the cup
    Paint the batch onto a surface.
    Sand the surface with 180 paper by hand.
    Apply a paint to it, but not jist any paint. Use say a spray paint. If the paint has fish eyes; the cause would be cup contamination. My primer coats were contaminated by the S/W paint trays. There is nothing I can do to fix it. The crap is embedded in my finishes. When I repaint; they will just reappear. A hideous nightmare..
     
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