Is epoxy epoxy? Well known vs cheap brand epoxy.

Discussion in 'Materials' started by xellz, Dec 2, 2017.

  1. xellz
    Joined: Jul 2017
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    Location: Japan

    xellz Junior Member

    Not only boat building materials are hard to find in Japan and really little choice, but they also cost a lot. For example 3 gal of System three SilverTip epoxy will cost about 550usd, there is much cheaper epoxy available of ebay or in Japan (but never heard of those company names). From what i could find, most problems come from not protecting ratios and instructions provided by manufacturer, i.e. better to avoid pump and read instructions. Since i want to paint over, how clear is epoxy is of no importance.
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    West System and System Three brand epoxies are the two most costly of the commonly available stuff. Japan has epoxy formulators in country and you can order epoxy online, usually at 1/2 to 1/3rd of the price of the big boys and yes it has the physical attributes of the major brands.
     
  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Cheap epoxies usually have no technical support. That is worth a lot of money.
     
  4. upchurchmr
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    upchurchmr Senior Member

  5. xellz
    Joined: Jul 2017
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    xellz Junior Member

    Thanks for input, i thought about trying japanese epoxy on small project first before i go to larger boat. Difference between System Three and cheaper epoxy won't be that big on kayak, but on 30ft catamaran it's certainly noticeable.
     
  6. rwatson
    Joined: Aug 2007
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    rwatson Senior Member

    You might consider a mix. Brand name for exterior, no-brand for interior for example.

    I did a strip plank canoe in West Systems. It has spent many years up side down, in direct sunlight. The seats, also done in epoxy/strip/plank at the same time look like new, while the inside of the hull has gone dark, and mostly opaque. The outside of the hull is painted a dark colour, which goes against a lot of advice to paint epoxied hulls a light color.

    I guess the lesson is that even a brand name doesn't make epoxy anything but epoxy, and they all have their limitations.
     
  7. dinoa
    Joined: Oct 2007
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    dinoa Senior Member

    Checking out the data sheet for an epoxy helps.
     
  8. xellz
    Joined: Jul 2017
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    Location: Japan

    xellz Junior Member

    After searching for a while i could not find dedicated marine/boat building epoxy local supplier, but something similar is available. Could find several examples of use, but no big projects, small boats or kayaks.
    Some of properties for local epoxy (2 different epoxies, same price, same maker):
    Viscosity when mixed: 580, 562

    After curing:
    Specific gravity: 1.14, 1.18
    Compression yield strength N/mm2: 76.4, 78
    Compressive modulus N/mm2: 2200, 2200
    Bending strength N/mm2: 64.9, 69.3
    Tensile strength N/mm2: 43.4, 50.8
    Impact strength kJ/m2: 3.7, 3.9
    Tensile Shear Bond Strength N/mm2: 20.4, 25.2

    It's different from major companies in USA, but i'm not too sure how big is this difference. Since it was used successfully on kayaks i think i'll try it too. 2kg resin, 1kg hardener will cost me only 70usd.
     
  9. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    used to ship gallons of our Premium No Blush epoxy to a private boat builder in Japan. Thanks to new shipping regulations cannot ship outside the USA anymore.
    check the msds or SDS sheets for chemicals used added to the epoxy

    this link to compare different clear marine epoxies

    www.epoxyproducts.com/mepoxies.html

    paul oman
    progressive epoxy polymers inc.
     
  10. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    don't put too much faith in the numbers. The formulators usually extrapulate them from the raw chemical suppliers numbers. Also, everything changes when you add fiberglass cloth into the mix (or fillers, etc.)
    everyone will have similar numbers - it is sort of an apples to apples comparison. Look for % of nonyl phenol in the formulation. - Huge amounts not OK, lesser amounts are OK

    paul oman
     
  11. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Make sure and get no blush epoxy. Anything else is a pita.

    Another rookie error is viscosity. Compare to Silvertip.

    Silvertip is my preferred epoxy. Surprised you can’t get it for 120 a gallon plus ship. Anything over a buck an ounce is too much. Send a message to rxcomposite and see if he has a recommendation.
     
  12. xellz
    Joined: Jul 2017
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    Location: Japan

    xellz Junior Member

    What shipping regulations? I'm currently thinking on ordering all materials from boatbuilder central because i can't really get a decent source locally. Only marine plywood sold here is birch, which is quite a bit more heavy. But also thought that epoxy might be a problem and better to make sure i can import before ordering. They do have inexpensive marine epoxy and it was also used on Richard's own Skoota 28 and looks like there are no problems with it.
     
  13. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I am a customer of bbc. I hold them in high regard. I would recommend using Silvertip for anything you intend to finish bright. It has better outgassing qualities than any epoxy I have ever used. The forum there is also helpful with nitty details.
     
  14. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The physical properties of SilverTip and Bateau's Marinepoxy are nearly identical, so buying SilverTip is just paying 2.5 as much for essentially the same thing. In fact, knowing where they're getting their raw stock, it's the same as most other formulators, so literally the same thing, except for minor additives in their hardeners.

    Getting "blush free" formulations is just a marketing tool, really. Most home build shops, just don't have the environmental controls to take advantage of this, so if you're wise, you always assume a blush, even if a modest one (also bugs, dust, wood chips and other contaminates) and wash any cured surface, before applying another coating (of any type).
     

  15. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    Amine blush is caused by co2 in the moist air that forms a waxy film on the epoxy as it is curing. If the blushing happens to be bad it can mess up the adhesion of the next coat of epoxy , paint, etc. - (one more thing that can go wrong). So using a blush free epoxy is one less thing to worry about. - Why formulators even offer a blushing epoxy is beyond me.... (it is a bit cheaper of course) when a slight change in the formulation can 'save the day." Sort of like buying a car without seat belts or with seat belts....

    paul
    progressive epoxy polymers inc
    epoxyproducts.com
     
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