Conference vmszoo::rc

    You may have a problem getting it to cure at all if the mix was
    that far off.  I had this unfortunate experience once when working
    on a boat in the winter.  My garage was probably at about 55 degrees.
    I had to scrape the stuff off and use acetone to clean off the rest.
    Epoxy is fairly sensitive to mix ratio because the hardener gets
    used up in the reaction instead of acting just as a catylist like
    the stuff for polyester does.  When all of the hardener reacts,
    you're done.  If extra heat doesn't do it, it's time to try to get
    the stuff off.  By the way, most epoxy and polyester does not cure
    well below 70-degrees.  I have to use a heat lamp to help it along
    in the winter because I can't afford to turn the heat in my shop
    up to 70-degrees.  The lower temp does help pot life though.  I
    used to pack the polyester resin can in ice when I worked on boats
    in hot weather to extend the pot life.  
    
    Charlie
    

    Kay,
    
    You "already" know this [now], but what you did is a no-no with
    epoxies.  Proper polymerization/curing of the epoxy depends upon 
    proper mixture of the two-parts.  There's an excellent chance that
    it'll "never" cure, even give a year or more!  Epoxies "do not"
    air cure through evaporation of solvents....they cure chemically,
    depending on correct proportions of the two agents to cause a
    chemical change to a solid and will do this even in a vacuum.
    
    Heat merely accelerates the chemical curing process.  Conversely,
    cold retards it.  But, key to the process is the correct mix....
    without this, you may be "dead."
    
    Even allowing a week to see if a miracle might occur, you should be
    aware that, even if it does eventually cure, the strength of the 
    resultant joint might be substandard...I'd hesitate trusting it on 
    such a critical joint as the wing center-section. 
    
    If you still can, I'd separate the wing halves using heat, if
    necessary, to fascillitate things,  Plain old Isopropyl [bathroom]
    alcohol should clean up the residual mess well enough to reglue
    it with fresh epoxy...just be sure it doesn't attack the foam - it
    shouldn't.
    
    G'luck and let us know how you make out.  Adios,	Al

    Kay,
    
    After entering my reply and reading Charlies, it occurs that a little
    more understanding about epoxy might benefit other noters, in addition
    to yer'self.
    
    As Charlie intimates, epoxy is NOT a resin and hardener substance
    like polyester resins.  That's why it's usually labelled part-A
    and part-B...each part is integrally/equally important to the chemical
    reaction which converts it to a high-strength solid, each containing
    half of the required polymers.
    
    The best analogy I've heard compares epoxy to velcro: think of part-A
    as being chemical "hooks" and part-B as being chemical "eyes."
    If you'll think of it this way it'll be easy to understand why,
    even if it "does" cure, an inferior substance will result...you've got
    only half as many chemical "hooks" as "eyes" to form the "velcro" so 
    maximum strength "CANNOT" be achieved!                           
    
    Adios amigo,	Al

        One of the interesting things I've learned about epoxy is that you
        can vary the mix slightly, although your 50% is probably too far.
        While it isn't surprising that less hardener will take longer to
        harden, I was surprised to learn that the result will be harder
        than normal. More hardener will speed the reaction, but never get
        quite as hard as normal. 
        
        Several years ago, I was trying to cast solid parts from polyester
        resin. Mixed normally, the parts would crack from the reaction
        heat. With half the catalyst it took much longer to harden, but
        didn't crack. The resulting castings were very hard, kind of
        amber-like, and quite machinable on my lathe. This also works
        with materials like Bondo.
        
        In general, it's better to follow the directions, as you've now
        learned. 

        One more thing I forgot. Sometimes I thin epoxy resins for
        fiberglassing (Kevlaring? it's harder to wet Kevlar than glass). I
        use Safe-T-Poxy, which can be thinned with 20-50% isopropol (sp?)
        alchohol. If thinned to extreme (50%) the result won't set up in
        the pot, but will set in thin films. 

    I had decided to replace the nose of a trashed Gentle Lady with foam
    and a fiberglass skin.  The two epoxy (Locktite 30 minute) bottles
    weighed about the same, so I decided for this much quantity to measure
    by weight instead of volume; my scale sensitivity is 0.1 ounce, and I
    weighed out about 0.4 ounces of each.
    
    After 63 hours of warm sunlight, heat lamps, and other attention, the
    fiberglass is still sticky.  I suspect I have now _really_ trashed the
    Gentle Lady --- this will never harden enough to sand.
    
    Alton, who now wishes he had used polyester resin.
    
    p.s.  This note was found in seconds with the technique of note 2.4 and
    the Boolean options of the VMS SEARCH command.
    
    Notes> $ SEARCH/MATCH=AND RC11.A fisher,epoxy

    I've solved my problem.  I scrubbed off all of the uncured epoxy and
    embedded glass with alcohol, dried it off, and started over.  My only
    epoxy alternative in the shop was PIC's 4 1/2 minute epoxy, so the
    fiberglassing was a bit exciting, but it worked.  

    I found another note by Kay that was directly applicable. To quote,

"I don't know what the problem was but thanks for reminding me to throw
away two nearly full bottles of Loctite Epoxy.  I used this to cover
the surface of my Hobie Hawk after I added some carbon fiber to the tail.  
Days later it was still wet.  ...... 90-100 degrees for a week or two.  
Then .... for a couple weeks .... Then I ignored it for another month.  

"I will only use Loctite on screws.  They can keep their epoxy."

    Loctite is a well respected name in industrial adhesives, but it may be
    that the mixing ratio has little leeway or that the shelf life is a
    problem.  Moreover, two of us have now had horrible experiences with it,
    so I for one will try other brands in the future.  And for other and
    obvious reasons, I will also avoid a fast epoxy for fiberglass layup.