Variations in Epoxy From Same Manufacturer?

Discussion in 'Materials' started by CatBuilder, Jun 5, 2011.

  1. CatBuilder

    CatBuilder Previous Member

    No bogging or fillet with medium epoxy? Really?

    I find myself waiting impatiently for epoxy most of the time. I always use fast when coating and sometimes use fast for cove joints if it's a little cooler out.

    Why wait around forever for the stuff to full cure? If I use fast or medium, after sitting out in 100 deg temps all day, my part is ready for full loading or sanding the very next morning. Makes for a much more efficient work schedule.

    I only use the Sys 3 Gen Purpose epoxy (medium and fast) for coating and bogging. It's flexible, so it's great for those applications.

    I use Sys 3 Silvertip for laminates. It's completely different stuff. Wets out really well and has 1/2 hour for fast and a full hour for slow at 77deg F. Of course, it goes faster in the heat, but it's just fine.

    I prefer to use the General Purpose medium and fast so I don't have to waste time post curing. The slow hardener for System 3 Gen P is the only epoxy they make that requires a post cure. I'd rather not waste all that time post curing. It's only for bogging and coating, so no reason not to use it.

    I did a cove yesterday (101F again) using medium and it came out beautifully.
  2. CatBuilder

    CatBuilder Previous Member

    You know what? I think I did an extra large batch that time too.

    In the future, I'll just do the smaller batch, apply, form cove, mix a new batch, continue cove, repeat until cove is done.

    I really don't want to post cure. :)
  3. CatBuilder

    CatBuilder Previous Member

    Thanks. Actually, the last bulkhead went in yesterday (for this hull). This does not count bulkheads that are inserted attached to beams. Those go in during hull alignment later.
  4. CatBuilder

    CatBuilder Previous Member

    Who am I talking to here?? Where did all of bntii's posts go?!?
  5. rberrey
    Joined: Oct 2010
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    rberrey Senior Member

    I hear you cat, got my note book.
  6. bntii
    Joined: Jun 2006
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    bntii Senior Member


    I was in a foul mood working in the heat on some boats today...

    I distrust anything I say when off my oats & thought I was lecturing so I dumped the whole lot.

    The good news I finished off the day milling a nice bit of corian for around the galley sink on our boat.

    Good on ya Cat- I can't wait to see the launch photos.
    1 person likes this.
  7. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    Whew! I am relieved to see that post, bntii.
  8. CatBuilder

    CatBuilder Previous Member

    Is that what gentlemen do? I usually leave my rants and off color posts up for all to see! :D

    I didn't see anything foul or wrong with your posts, for the record. They seemed ok to me.

    Oh well. Glad you're back in the thread.

    Launch photos will be quite a long time away. I only have one hull nearly done! :eek: Still another to go, plus beams, boards, rudders, bridgedeck, house, final fairing and painting, outfitting for splashing, etc... :(

  9. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    Does the quality of the cure remain the same with the different gel times?
  10. CatBuilder

    CatBuilder Previous Member

    I really am enjoying FL's weather for building boats.

    Now, with the air conditioner, I can take the building and bring any humidity down to about 50%-60% in a matter of an hour or so. The temperature over the whole building doesn't change much, but the 14" duct blows a heck of a lot of cold air right on you and/or your work area used for spot cooling. You can throw the duct into the hull and the whole hull comes down to a temperature that even I, from the north, get cold in. :)

    I can work out there in any temperatures, so long as the working area is small. This is very different from last summer's learning curve.

    I'll be doing rudders, dagger boards and main beams this summer in a small "tent inside a tent" in order to control the temperature and humidity for those projects. The next hull will be done in the fall when the temperatures and humidity go back down - when rainy season ends.

    I usually start in at 5AM or 6AM, with the air conditioner started an hour before.

    I then do my work/laminations until early afternoon, at which time I let nature "post cure" my layup. I turn off the air conditioner in the afternoon and allow temps to climb to 100 degrees F (38 deg C) all afternoon long in there, really locking in my work.

    It's really working out well. The air conditioner has allowed me to produce perfect quality work all year 'round instead of just in the winter.
  11. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    Thereby effectively close to doubling your build speed, no?
  12. CatBuilder

    CatBuilder Previous Member

    Not doubling, but maintaining it at full capacity year round instead of struggling in the summer and ending to with poor quality.
  13. Herman
    Joined: Oct 2004
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    Herman Senior Member

    In your climate, I would not worry about postcure. This is a one-time operation, which can be done by putting the thing in the sun, turn it around a couple of times. (hope it will be sitting on a trailer of some sort) Or just let the temperature rise as much as possible for a couple of days.

    Humidity is accelerating epoxy. It also can make coatings cloudy, so use a fast hardener for that.

    As for the 2 bottles: If you want to be absolutely sure, do a side-by-side test, with equal amounts. The colour does not say much. They are specified as "Gardner colour" and can range from clear to dark brown. Some epoxy resins can really differ from batch to batch.
  14. Alan.M
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    Alan.M Junior Member

    That'll do it every time.

  15. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Not really, in general the cooler the temp, the longer the gel time, the poorer the cure.
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