carbon prepreg - releasing problem

Discussion in 'Fiberglass and Composite Boat Building' started by martymcdowell, Aug 16, 2011.

  1. martymcdowell
    Joined: Aug 2011
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    Location: new zealand

    martymcdowell New Member

    hello. i have recently changed method of production building carbon racing paddles. i have gone to prepreg from hand lay up. they have been going well. but i am having trouble release the part from the mould. i am using TR high temp wax and fully followed the direction but it still seems to be hooking up. does any body have any more info regarding releasing and what boat builders use to release.
    thank you
     
  2. wet feet
    Joined: Nov 2004
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    wet feet Senior Member

    Two posts about the same problem?What is the mould material?Were the moulds newly made for the prepreg version?If the old moulds were used,were they preheated to drive out any residual styrene?What cure temperature prepreg wre you using?You're not the only one asking questions.
     
  3. martymcdowell
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    martymcdowell New Member

    i have made new moulds. epoxy high temp with a high temp tooling gel coat. they had been pre heated as to achive full cure is was required to heat to 90C for 6 hours. i am using toray prepreg high temp, cooking for 25mins at 110 degrees C.
    sorry about the double post. new to boatdesign.
     
  4. Jeremy Clarkson
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    Jeremy Clarkson Junior Member

    maybe try using authentic carinuba wax or whatever that is heavy duty.

    Also Is buying pre preg material cheaper than buying the material and epoxy?
    Is it a little more expensive or a lot?
     
  5. martymcdowell
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    martymcdowell New Member

    thank for that. i havnt heard about the carinuba wax but have just been looking at it on the net. from what i have read it seems very ggod. also in an aerosol. has any body had any experiance with this? its hard to take the maufactures word for it as they always try and say they have the best.
    look forward to hearing about it.
     
  6. wet feet
    Joined: Nov 2004
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    Location: East Anglia,England

    wet feet Senior Member

    Most of the prepreg carbon components I know of were released after the application of Frekote or similar semi-permanent release agents and these are satisfactory with the 125C cure temperature of the commonly available prepreg.I am reassured to see that new moulds were made for the project to take into account the elevated cure temperature and would be even more relieved if it were made clear the the fibre used for the moulds was carbon and not glass.This would remove the possibility that the differing coefficients of thermal expansion were causing a dimensional conflict-ie the mould is nipping the component.
    Totally agree with the comments about manufacturers claims,but with the note that the manufacturers claims are sometimes inflated by commission hungry salesmen.Speaking to the technical support people can be very useful and if you are having a problem even when you use their product in accordance with the instructions,they can sometimes be persuaded to investigate the problem.Not too likely a scenario if you have only ever bought a single can of their product.
     
  7. Herman
    Joined: Oct 2004
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    Herman Senior Member

    It is not very likely that a 90 degree cure for 6 hours will generate a Tg that is over 110 degrees. Or that a 6 hour cure will get a full cure anyhow.

    So it is very likely that the mould co-cured with the part.

    The TR-104 wax is a good wax, I believe it has carnauba as well. However for these higher cures I would recommend a semi permanent system, consisting of a sealer and a release. There are many out there, I could recommend the Ferrokote system, or Zyvax.

    As a sales person I pretend not having read the comments about them....
     
  8. latman
    Joined: Mar 2010
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    latman Junior Member

    surely whatever release worked for pre preg resin will also work for wet lay ups ?
     

  9. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    Depends on the demands.

    Most semiperms are quite agressive, which means that when resin is rolled in a semi-permed mould, the resin will roll down. Depends on resin viscosity and rheology as well...

    If needed, apply a layer of high temp wax over semi-perm, to make things suitable for a gelcoat.
     
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