freezing west 105

Discussion in 'High Power Rocketry (HPR)' started by watermelonman, Jul 20, 2015.

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  1. Jul 20, 2015 #1

    watermelonman

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    My favorite new trick is putting leftover West 105 into the freezer, where it will fail to set for at least a day or so. Thanks terryg!

    I am betting this has no significant effect on strength, but what do the epoxy experts think?
     
  2. Jul 20, 2015 #2

    JoeG

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    Not an expert but your idea brings back memories of working for Lockheed building subassemblies for the C5A back in the late sixtiies, early seventies. We would get a tube of sealer from the tool crib to seal the space between the skin and substructure plus all fasteners were sealed as they were added to the skin. This sealer was taken from the freezer. Not sure what the shelf life was after thawing but it seemed like it was about four hours. The tool man would mark the time of expiration on it when you picked it up. I'm sure this was an epoxy of sorts and being frozen didn't seem to have any negative effect on it.
     
  3. Jul 20, 2015 #3

    amell

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    Why would west system 105 set? I've got some and it hasn't set for over a year at room temperature.

    Are you saying that you have added hardener such as 205/206? If so, I thought it would be exothermic in which case freezer wouldn't help much?
     
  4. Jul 20, 2015 #4

    watermelonman

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    Yes, after mixing, the cold will slow hardening to the point that I can let what I assembled set and use the remainder on the next task.

    Sorry, that first message should say mixed epoxy not 105. I have a habit of calling the entire family 105.
     
  5. Jul 20, 2015 #5

    CZ Brat

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    It is exothermic, but it also reacts quicker when it's warmer. That is why they often give a table of cure times based on the air temp. The cooler it is, the longer the pot life.

    The warmer it is, the greater the exothermic reaction, which makes it warmer, which increases the exothermic reaction, which makes it warmer, which.... you get the idea.

    I was using a special epoxy once that had a 24-36hr cure time. But I wanted it done in 3-5 minutes. I hit it with a heat gun. About 3 minutes in, it instantly went from liquid to solid. Must be a very specific temp it had reached and instantly cured (or at least, got rock hard).
     
  6. Jul 21, 2015 #6

    jd2cylman

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    Yep, I've been doing this for years with West 105/205/206 and Proline 4100. HOWEVER, it does NOT work for RocketPoxy. :eek: I've tried, and once it thaws it's already set.

    Adrian
     
  7. Jul 21, 2015 #7

    raptor22

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    This is essentially a really low temperature version of the pre-preg process.

    For those who don't know, most professional composite parts are made with a laminate that comes impregnated with a premixed epoxy resin. It has a definite shelf life, even in the freezer, but at room temperature it won't properly harden until it has been baked in an oven at 250+F.
     
  8. Jul 21, 2015 #8

    G_T

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    Just don't use a freezer you use for human consumables.

    Gerald
     
  9. Jul 21, 2015 #9

    watermelonman

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    Thanks for the responses but I am still looking to find out if the freeze has any impact on strength. I wrote West themselves and will try to report back.

    I put it in a zippie bag. Do you expect that would suffice or would you still be concerned? Sadly a second refrigerator is simply not possible here.
     
  10. Jul 21, 2015 #10

    blackjack2564

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    General statement about freezing on AP's FAQ's.............. West has one too...this came up first on Google.


    http://www.ptm-w.com/index.asp?pgid=200

    Apparently no ill effects.
     
  11. Jul 21, 2015 #11

    watermelonman

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    Shoot, I definitely tried but must have been searching the wrong terms. Thanks!
     
  12. Jul 21, 2015 #12

    G_T

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    I recommend keeping chemicals well separated from edibles and drinkables. I do not consider a zip lock bag suitable separation. If you just need to do it overnight, get a cheap styrofoam cooler and fill with ice. Use it only for chemicals.

    Ditto things like warming chemicals in the microwave or the kitchen oven... also a very bad practice.

    Gerald
     
  13. Jul 22, 2015 #13

    watermelonman

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    So here is the scoop from West -
    It is probably fine. The biggest concerns are of course timing and contamination. If all goes well strength will not be compromised.

    However, the great customer service showed me a link that looked appealing enough as an alternative -
    http://epoxyworks.com/index.php/smaller-can-be-better/

    I was previously hesitant to measure small amounts but I like this technique and I think I will be switching from freezer saving to this.
     
  14. Jan 22, 2016 #14

    watermelonman

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    I am still loving that syringe method, but recently was using West on a tiny rocket where even that was way too much. I froze, thawed, used, froze, thawed, and used again. It seems to be taking an awful long time to harden all the way, though my ratio might not have been perfect either.
     
  15. Jan 22, 2016 #15

    blackjack2564

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    I just keep some West in Syringe's all the time for dealing with small amounts. I leave the tips on, unlike method shown in FAQ.
     
  16. Jan 22, 2016 #16

    pcalviln

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    Just make sure you don't expose the cold adhesive to room temp air. Make sure moisture no longer condenses on the container before you open it up, and don't use heat to speed up the thawing process. As said before, it is still kicking in the freezer, just at a slower rate, I've pulled pre-pregs out of -15 freezers that would not flow for anything in cure. But I've pulled old Orion pre-preg (6 year old material, shelf life listed as 1 year) that still works wonderfully.
     
  17. Jan 22, 2016 #17

    G_T

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    West Systems puts out a great deal of heat if it really gets going (don't breathe the smoke and fumes). If the volume is sufficient the outside will insulate the core sufficiently that the core will still rise in temperature. As it rises in temperature, the cure rate accelerates, so the heating goes up. This then heats the rest from the inside and then it all accelerates. It will get quite hot quite fast, likely breaking whatever container it is in. There should be a shape dependent threshold on volume of epoxy, also dependent on initial temperature and external cooling rate, where a volume is no longer safe.

    Prepregs have a relatively minimal layer of epoxy and are in sheet form - providing a high surface area to volume ratio. Also prepregs don't usually use epoxy systems that are strongly exothermic like West Systems.

    Gerald
     
  18. Jan 26, 2016 #18

    TMR

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    Glad I read this!
    I will try the syringe method for mixing smaller amounts. I hate waste.
    Last night I mixed up some US Composites 635/Medium hardener for this tip-2-tip fg job.....too much was mixed. Stuck it in the freezer. 22 hours later, unthawed it. It was only mildly thicker than when fresh, added a few drops of acetone, and used the rest of it.
    Test complete!
    Thanks for another great tip!
     
  19. Jan 26, 2016 #19

    G_T

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    Um, acetone is not a great choice for thinner for epoxy. Most thinning damages the structure to some extent. At least you only added a little. A few percent of some solvents can cost 40% strength. Generally the proper thinner is to use a thinner epoxy to start with (not applicable in your case). The second proper thinner is to warm it a little - though this is really only useful for long cure epoxy systems which benefit from elevated cure temperatures to reach full cure. The third proper thinner is benzyl alcohol as I recall... Recommend avoiding it.

    Please note that excessive cooling of epoxy can cause crystallization of one of the components in the resin. Warming it up causes the crystals to dissolve. Usually this cycle causes no damage. But insufficient mix + cooling may result in a condition where microcrystals form and effectively alter the curatives ratio. I don't have the data on it.

    http://dowac.custhelp.com/app/answe.../dow-epoxy---crystallization-of-liquid-resins

    Gerald
     
  20. Jan 26, 2016 #20

    TMR

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    OK, thanks for the heads up! I would normally never thin epoxy for layups or bonding. This particular tip2tip fg job is merely cosmetic. It is curing nicely.
    I have seen a video of someone thinning epoxy with denatured alcohol. Tried that, but didn't like it.
     
  21. Jan 26, 2016 #21

    Barkley

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    I extend my pot life like this:

    [​IMG]

    Both containers are from a take out spot. Half fill the bigger one with water and freeze it, then mix your epoxy in the smaller container and nest it in the ice/water bath. If you stir the epoxy regularly it extends your pot life dramatically.

    RE OP, if you can't freeze 105 then most of the sailboats in the great lakes would sink. As a sailor from Toronto, the majority of my experience using West involved watching the forecast, hoping for a sunny, rain-free Saturday in April above 8C/46F so that you can touch things up before the boat gets launched.
     
  22. Sep 3, 2018 #22

    soopirV

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    So...totally necro-ing this thread, but I'm glad the new forum offers better searchability than the old one! Aside from extending the utility of epoxy (because too much was mixed), has anyone tried to use this as a way of getting epoxy into particularly difficult areas? I need to put a bead on the aft side of the forward CR of a build I'm working on; I thought of dribbling thickened (but not thick) epoxy into a fin slot, seating the MMT home, and rotating on a rotisserie over night, but that would put a ton of epoxy on the MMT- and if I thicken it too much, I won't get a good bead...too little, and it will flow out. If, however, I build a tape dam around the outer diameter of the CR, leaving a few mm clearance, I could lay a bead of thickened epoxy down, freeze it, remove the dam, and then seat it home, allowing the thickened and properly located bead to melt, flow and cure...

    I ask because I first saw mention of this on a boat building forum, but there, like here, the question was mostly, "I made too much, can I trust it?" and the answer seems to be "yes", so why not put this property of time-delay to our advantage? Any reason not to?
     

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