Thinning epoxy

Discussion in 'Fiberglass and Composite Boat Building' started by Jetboy, Feb 28, 2013.

  1. Jetboy
    Joined: Feb 2012
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    Jetboy Senior Member

    I'm building in glass and epoxy. I struggle to wet out thick fiberglass. For example this weekend I put a layer of 20oz triaxial glass over my centerboard core. I really struggled to wet it out completely. I stuck it in a vacuum bag and that helped compress some, but there are still a few white spots. Is there any good way to thin out epoxy?
     
  2. Dirteater
    Joined: Oct 2010
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    Dirteater Senior Member

    Hi Jetboy,

    not exactly sure of your application, but the one thing I can think of is,
    I wonder if "over-stirring" may be a contributor when you mix your epoxy?
    thus creating too many air bubbles.

    just a thought,

    DE
     
  3. PAR
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    PAR Yacht Designer/Builder

  4. Jetboy
    Joined: Feb 2012
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    Jetboy Senior Member

    I may try to buy a low viscosity epoxy and see how that goes. I'm worried about heating it causing it to cure too fast to use.
     
  5. tunnels

    tunnels Previous Member

    Warm all not heat ! could use a slower hardener !

    Theres a big differance between heating and warming !!! simply warming will make it thinner ! only takes a few degrees!!, also warm the part where you glassing ,warm resin onto cold parts is cooling it instantly .
    Try also wetting the clothout before you place it on the job , cut to fit lay flat in a sheet of what ever then lift up into place . is easyer and quicker to bring the resin up through the glass than trying to push it down from the top ! if you vac bagging use a little more resin than you been using and roll the glass out with a hard roller then peel ply and vac bag .
    Also a slower hardener helps !! takes longer but makes a better job and get more time to get all done then bag it !!:D
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I thought I answered this, but I must have pressed the wrong key. Tunnels has it right.

    Warm the substrate, use slow or super slow hardener and select a lower viscosity resin. Raka is known to be thin, as are a few others. Wet the substrate, apply fabric then add more resin. You force resin in from both sides this way. Lastly, don't get greedy with laminate layer thicknesses. Triax is always a pain in the butt to wet out.
     
  7. DGreenwood
    Joined: Aug 2004
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    DGreenwood Senior Member

    Guys...what about sizing or binders. Where did the glass come from?
     
  8. coolgps
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    coolgps Junior Member

  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Incompatible sizing is hard to run across anymore, though It's possible.
     
  10. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    West System with Slow hardener at 100degrees F is very easy to apply consistently and does not speed up the cure noticeably.
    That is the overnight temperature in my garage in July / August.
    I have not tried anything as thick as 20OZ, and never will . You will put lots of epoxy into the weave of the cloth, costing you lots of money and weight.

    Listen to PAR, no thinning. Causes low strength. If you did that why buy epoxy?
     
  11. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    thinning the epoxy will not help the wet out that much. Wetting out is much more than viscosity. We use a very thick epoxy paste with fiberglass cloth for industrial pipe repair - it wets out the glass fine, just maybe 50% slower.

    thinning the epoxy will weaken the properties and the solvents need a way to flash off.

    fix is not with the epoxy but rather with technique.

    --- Par --- have you tried the aluthane product I sent you yet? --

    paul
     
  12. Jetboy
    Joined: Feb 2012
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    Jetboy Senior Member

    Possibly infusion is a better option for thicker layups? My design requires 14 layers of 20oz triax on each side of some beams. SO I'm going to ultimately need to layup some pretty heavy layers of glass. Ideally I'd like to lay up all 28 layers at once, but at least I'd like to put 14 at a time on. The plans are for polyester - I'm using epoxy. Possibly it would have been a lot easier with polyester because it's so much thinner, but I'd like to continue with epoxy.
     
  13. Red Dwarf
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    Red Dwarf Senior Member

    If you want to stick with epoxy buy a low viscosity resin such as the ones tailored to infusion.

    Another option is to go to a vinyl ester resin. It is very similar to epoxy in mechanical properties but as thin as polyester for easy wetout.
     
  14. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    for infusion you also want a slow epoxy so you have time to set things up, get things going, and work in a decent batch size. Something like Basic No Blush marine epoxy with slow (summer) cure.
     

  15. michael pierzga
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    michael pierzga Senior Member

    14 layers of 20oz cloth may generate heat...be careful
     
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