Surfboard Resin for Boat Building? (Entropy SuperSap CLR)

Discussion in 'Materials' started by bryson, Sep 12, 2019.

  1. bryson
    Joined: Dec 2018
    Posts: 5
    Likes: 0, Points: 1
    Location: Charleston, SC

    bryson Junior Member

    I might have access to enough resin to do my whole skiff, but want to make sure that it isn't going to give me any issues. Has anyone used resins that seem to be geared more toward surfboards or wood boats due to the "clear" attribute? I can't imagine it would be detrimental to building boats, but I have no experience.

    When comparing to the West System epoxy kits, it looks to be adequate in all areas except Tg, which I'm assuming is glass transition temperature, even though it's not a thermoplastic? I could be interpreting that wrong, since even the West System Tg seems lower than you would want on a boat.

    https://shop.fiberglasssupply.com/Entropy_Epoxies_Green_Surfboard_Epoxy.html
    3 Qt. Kit SuperSap CLR/CLF Clear General Laminating Epoxy
    Tensile Modulus 440,000psi
    Tensile Strength 9,500psi
    Elongation 5%
    Flexural Modulus 440,000psi
    Flexural Strength 13,500 psi
    Compression Strength 11,330 psi
    Tg Onset (F) 102
    Tg Ultimate (F) 149
    Hardness Shore D 70-80
    Bio Based Carbon Content (%) 17
    Mix Ratio by Volume 2:1
    Mix Ratio By Weight 100:47
    Viscosity (A/B/Mixed) @ 77F 1850/265/725
    Pot Life @ 77F 25

    https://shop.fiberglasssupply.com/WEST_System_Epoxy_Kits-WEST_System_105_Kits.html
    206West System Epoxy Slow Hardener 1.2 Quart Kit.
    Weight 3.1
    Tensile Modulus 4.60E^5 psi
    Tensile Strength 7,320 psi
    Elongation 4.5%
    Flexural Modulus 4.50E^5 psi
    Flexural Strength 11,810 psi
    Compression Strength 11,500 psi
    Tg Onset (F) 126
    Tg Ultimate (F) 139
    Hardness Shore D 83
    Viscosity (A/B/Mixed) @ 77F 725 @ 72F
    Pot Life @ 77F 21.5

    Can anyone offer any advice? I would hate to tell the guy offering it to me that I can use it, but then end up using something else.

    Thanks,

    Bryson
     
  2. Deering
    Joined: Feb 2005
    Posts: 477
    Likes: 22, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    As I understand it Tg is the temperature where it begins to lose strength, starts to soften. If so, 102F seems pretty low for a boat in a warm area, or where it would be exposed to direct sun. I’d consider using it where I am (Alaska), but probably not in South Carolina.

    But maybe I’m interpreting that incorrectly. No doubt someone here can give a more informed answer.
     
  3. KeithO
    Joined: Jul 2019
    Posts: 112
    Likes: 11, Points: 18
    Location: Michigan

    KeithO Senior Member

    Doing a post cure at an elevated temperature may improve the final Tg. Support the structure so it wont twist, cover with black plastic in direct sunlight for a few days.....
     
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