2 different hardners

Discussion in 'Fiberglass and Composite Boat Building' started by Tungsten, Nov 11, 2012.

  1. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    i'm doing a layup this afternoon on a foam core(corcell) i dont think i have enough slow hardner to complete.could i wet the foam with int. hardner then lay the glass and wet out with slow? i will be vac bagging.

    thanks
     
  2. Submarine Tom

    Submarine Tom Previous Member

    I'd be more inclined to mix the hardeners together first.
     
  3. gonzo
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    gonzo Senior Member

    I've never had any problems laying resin mixed with different hardeners.
     
  4. Tungsten
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    Tungsten Senior Member

    well thats good to no Gonzo.turns out i had just enough slow to complete the job.
    thanks
     
  5. PAR
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    PAR Yacht Designer/Builder

    It depends on the hardener you use and the resin formulation. What specifically are you mixing with what? For example, you can use West System 205 or 206 hardeners, as interchangeable products (5:1 ratio), but you can't use West 207 or 209 in the same mixture (3.5:1), though you can mix and match 207 and 209. The same is true of other brands, so you need to check the mix ratio and if similar (within 10% of each other) you're good to go.
     
  6. Tungsten
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    Tungsten Senior Member

    i have east system resin and hardener,slow 235 and clear intermediate 237 both 3;1 by volume.or 30;100 by weight.

    so what i'm understanding is, say i'm 100 grams short of slow hardener i could add 100 g of int. to my slow, mix it up then add to my resin?

    this would have a better result compared to doing one layer of glass with int. then doing a layer of glass with slow?
     
  7. Herman
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    Herman Senior Member

    It is just a matter of calculation. You need to match the epoxy equivalent with the amine equivalent. This is true for single hardener and multiple hardener usage. You just might arrive at some odd mixing ratio, but that should not be a problem, especially when using scales and a calculator.

    For single hardener systems it is simple: amine equivalent / epoxy equivalent * 100 = mixing ratio. (100 : xx)

    For multiple I should look it up. But not now. (should get some sleep, METS tomorrow)
     
  8. Submarine Tom

    Submarine Tom Previous Member

    That's what I would think, but I've never done it.
     
  9. Tungsten
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    Tungsten Senior Member

    well this is good info,thanks.

    oh and edit,the east hardener is 835 slow and 837 int.
     
  10. PAR
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    PAR Yacht Designer/Builder

    Watch the the blush on that stuff (East), it's quite unrefined.
     

  11. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    never had a problem, that i know of ,my shop air is very dry.
     
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