Newbie questions about fiberglass and epoxy

Discussion in 'Boatbuilding' started by declan, Jan 20, 2013.

  1. declan
    Joined: Jun 2010
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    declan Junior Member

    Hi all!

    I built the "one sheet skiff" a couple years ago but I've got the taste for building again! This time I'm trying to build the "duckskiff", if you're familiar with it.

    For my first boat, I just did a simple screw n' glue, but this one calls for fiberglass and epoxy. However, the directions are a little sparse sometimes and I'm unsure of what type of epoxy to get.

    For example, all the epoxy I've used before in my life has been the type where it comes in two containers, and you have to mix them together to activate them. Is this going to be like that? If it is, and it suggests using a gallon to seal the whole boat, does that mean a gallon of each, or just half a gallon each so they add up to a gallon?

    If anyone has any suggestions on a standard type of epoxy used for this, I would love to hear them. Also, if anyone has any good guides on doing this, I'd gladly read them as well.

    Thank you!!
     
  2. CDK
    Joined: Aug 2007
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    CDK retired engineer

    There is a nice brochure about epiglass products at yachtpaint.com. It has all the answers.
     
  3. michael pierzga
    Joined: Dec 2008
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    michael pierzga Senior Member

    Only use NON BLUSHING epoxy. One gallon would infer one gallon of mixed product. For hardener choice I prefer slow. The extra working time with slow hardener at normal shop temperature allows you to avoid .. hurry up before it cures in the pot... stress and produces less waste.

    The epoxy bible is here... http://www.westsystem.com/ss/assets/HowTo-Publications/GougeonBook 061205.pdf

    All the common names like RAKA, MASS, SYSTEM THREE, EPIGLASS, GURIT produce similar guides.

    Also review the homebuilt aircraft forums for epoxy and material choices.

    Do some googling and ask your local material supplier for suggestions.
     
  4. missinginaction
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    missinginaction Senior Member

    Ohhhh....a Jeff beck fan! I am too declan.

    You're where I was a few years ago. OK, first thing, take some time to read the threads regarding epoxy and safety.

    http://www.boatdesign.net/forums/fi...hen-working-less-than-gallon-epoxy-45941.html

    http://www.boatdesign.net/forums/fi...t-building/epoxy-allergies-options-45637.html

    As a amateur like me, your probability of developing health issues with epoxy seems very low, never the less it's wise to understand the issues around using the stuff. Don't skimp on the gloves and masks, even with a small project.

    As to the question of how much resin, I'd say that you're probably OK with one gallon total (resin and hardener).

    As to the brand to buy? Well, that's like asking a hot rodder what kind of motor oil is best, you'll get all kinds of answers. Any of the major brands are fine and you'll just need a gallon, so price isn't as critical as it might be to those of us who buy many gallons.

    My only suggestion regarding what brand to buy would relate to the mixing ratios. Some famous brands feature a 5:1 mix. 5 parts resin to 1 part hardener. If you're just mixing a small amount this can be problematic as you need a very small amount of hardener. I prefer and use epoxys that are mixed in a 2:1 ratio. Small batches are easier to mix with this ratio and it's easier to count to 2 than it is to 5.

    Here's another link to some information on using epoxy. This little book helped me out a lot when I was just starting out.

    http://www.systemthree.com/reslibrary/literature/The_Epoxy_Book.pdf

    Good luck with your project,

    MIA
     
  5. declan
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    declan Junior Member

  6. missinginaction
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    missinginaction Senior Member

    I'm not a chemist so I'll leave the suitability issues to someone else. Keep in mind that based on the description this resin comes with a half gallon of "fast" hardener. An issue for boat builders, especially us amateurs and especially when we are new to the process is working time. You'll find that that 30 minute working time may be considerably less on a hot day (epoxy is exothermic). 30 minutes might not be enough time for you to complete some of your work anyway. Now, fast hardeners certainly have their place. For me though it's important to have the ability to vary the cure time depending on what I am doing. That epoxy book you're reading will address this. Many of the boat building resins have "fast", "medium" and "slow" hardeners. If I was buying say a gallon of resin I might buy 1 1/2 quarts of fast hardener and a pint of slow (assuming a 2:1 ratio). When I wanted more time to work I could mix in some of the slow hardener with my fast to give me more working time. Over the years I've noticed I want to slow down the cure time much more often than I want to speed things up.

    MIA
     
  7. michael pierzga
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    michael pierzga Senior Member

    Also consider viscosity of the resin.

    A thin resin is very nice for fast wet out, but is prone to running out of a verticle laminate, a thick resin is troublesome to impregnate with and requires a sharp eye to spot dry spots. .

    Epiglass is a thin resin. West is a medium resin .

    Which s better...no answer. each has its use.

    I dont have much experience with other resins. Im not sure what your project is but the product called Peel Ply is very useful and should be part of your epoxy tool kit.
     
  8. Grady300
    Joined: Jan 2013
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    Grady300 Junior Member

    I have used several different epoxies. Aero Marine is by far my favorite. It's non blushing, wets out well, according to the manufacture up to 24 hours between coats and you still get a chemical bond and no sanding between coats unless you wait to long. Personally I don't go over 12-15 hours between coats depending on how hot it is outside. Any longer than that then sanding is required IMHO between coats. I would wait 48 hours if I had to sand between coats to let it cure a little more befor sanding or it will not sand well and gum up the sandpaper. 2:1 mix ratio also helps with small batches to get the mix right. PLEASE READ the application guidelines using epoxy like not allowing the glass to float, sanding between coats if it cures too long ect. Or you will not have a long lasting product.
     
  9. michael pierzga
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    michael pierzga Senior Member

    What is the price relationship...Aero against the typical West of Epiglass.
     
  10. declan
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    declan Junior Member

  11. Grady300
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    Grady300 Junior Member

  12. Grady300
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    Grady300 Junior Member

    I have had no issues with drying to fast I normally don't mix more than a quart at a time though. Once it gets out of the container on the wood you have plenty of time. If I am doing a large section of the build I have mixed up to 1/2 gallon. It does flash off faster if you mix in a filler than when just using straight epoxy. I have never had it start to smoke like I have with West systems.
     
  13. michael pierzga
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    michael pierzga Senior Member

    The price is certainly attractive,.

    Best thing to do is purchase a jug and test it out !!

    The critical feature is non blush.

    Working time is only a preference and there are logical strategies for extending pot life.
     
  14. Grady300
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    Grady300 Junior Member

    Fully agree on all points. I know a lot of Tolman builders on www.fishyfish.com once they try the Aero Marine really like it.
     

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

    For the novice laminator, I recommend the 2:1 stuff from Bateau.com - Marinepoxy. It's $60 a gallon and this can drop to about $50 a gallon if you buy 3 gallons or more. The slow is non-blushing. I've also good reports about Progressive Epoxy products as well, so check out Paul's site at Epoxyproducts.com

    When they say you need a gallon, this means a "mixed" gallon, regardless of mix ratio. All epoxies are resin and activator (hardener). If there isn't an activator, it's not really epoxy.

    Download the user's guides at westsystem.com and systemthree.com. This free publications will help nurse you though the processes.
     
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