Another Vinyl Ester vs Epoxy question...

Discussion in 'Materials' started by Jetboy, Mar 6, 2012.

  1. Jetboy
    Joined: Feb 2012
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    Jetboy Senior Member

    I'm sourcing materials to start building an 18' sailing trimaran. Construction will be fiberglass over honeycomb core. Original plans call for polyester resin or epoxy.

    It seems as though I can find poly, vinyl ester, or epoxy for the same price. I've never worked with any of them in a project like this.

    Seems like the price is around $60/gal for all three.

    I understand the mechanical and chemical properties of each, and I'm confident that all of them would be sufficient structurally for this little boat.

    Which would you choose and why? Of course the strength of epoxy is a big draw, but I'm also thinking it's overkill and may just make the boat harder to build without any meaningful improvement in the final product. Which is the easiest to use when fiberglass over honeycomb core is the construction method?

    Would you mix and match for different parts?
     
  2. CatBuilder

    CatBuilder Previous Member

    If they're all the same price, I would (and did) choose epoxy for ease of use. I'd stick to one resin for the whole project to make it simple.

    I'd also choose epoxy to be sure you are watertight - no blisters possible down the road.

    Epoxy is also (in my opinion) healthier to work with. If you do breathe it, at least it's not MEK you are breathing. It's some BPA and Amine (NH) hardener.

    It can cause some skin sensitization and itches like crazy if you get the hardener on your skin, but just don't.

    Also, polyester will stink up the whole neighborhood. Epoxy has very little smell outside the immediate build area.

    Lastly, polyester would probably make the build go faster since it can set up fully in a very short time period (hours), where epoxy take usually 24 hours until you can really sand it.

    Despite that, epoxy just has so many more benefits going for it.
     
  3. Jetboy
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    Jetboy Senior Member

    Thanks Cat Builder.

    I've never done fiberglass work, but I have painted automobiles. I'll plan on coveralls and I have a good respirator.

    I can buy the Resin Research epoxies for around $60/gal and the poly and vinyl seem to be right at the same price. Maybe I'm not finding the lower priced poly or vinyl? I don't really have a personal preference either way. Lower smell would be a GOOD thing as my wife's car will still be in her stall in the garage. I have to give mine up for the boat building.
     
  4. CatBuilder

    CatBuilder Previous Member

    Ah, you've done car body work. You do have some experience, then.

    You know the smell of Bondo? That stuff is polyester resin. Not pleasant.

    The place epoxy gets most often when building a boat is on your arms - from your wrists up to your elbows. Eventually, you just learn not to keep getting it on there, but that's where you get it most.
     
  5. rwatson
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    rwatson Senior Member

    VynelEster is really horrible to smell.
     
  6. DavidJ
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    DavidJ Senior Member

    Polyester is usually much cheaper than epoxy. 60 bucks a gallon would be on the expensive side for polyester. Polyester is easier to work with because it has a much lower viscosity. It therefore soaks into the glass easier and it can be applied easier. In general polyester cures much faster. However, the cure time of polyester can be altered by changing the ratio of hardener. This cannot be done with epoxy. The ratio is always the same. Polyester is compatible with gelcoats and regular fairing putties, like Bondo.

    Epoxy is a much stronger adhesive. It therefore bonds better to cores and other dissimilar materials. Yes, polyester does allow water to pass through which can lead to blisters. This process is incredibly slow and probably wouldn't be an issue with an 18' boat as I assume it won't be left in the water for months at a time.

    Polyester does smell worse than epoxy and respiration is highly recommended. Epoxy is a strong allergen that is a sensitizing agent. Some people never react and some react quickly after exposure and some only develop problems after many many years of exposure. Always wear gloves and avoid getting it on your clothes.

    In general epoxy is a higher quality material. Polyester is cheaper and easier to work with.

    http://www.shopmaninc.com/polyesters.html
     
  7. tinhorn
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    tinhorn Senior Member

    Man, I love the aroma of vinyl ester and polyester resins. More than WD40, even. On the other hand, I sold a dinghy once to a guy who told me about a boat he was repairing in his garage, under his house. He had to use epoxy just because of the odor issue.

    I bought a set of molds once from a guy who was operating his shop in San Diego, surrounded by homes and offices. I asked him how in the world he avoided complaints from the neighbors. He told me that styrene fumes were heavier than air, so his ventilation system sucked the fumes from his shop, mixed them with fresh air, and shot them up a 50-foot stack. By the time they returned to ground level, the parts per million were so low that they couldn't tickle the olfactories.

    When I built kit car bodies--not boats, mind you--I selected vinyl ester because it was reputed to have many of epoxy's virtues with polyester's ease of handling. In addition to increased strength over poly it also bonded better to metal, had a higher tolerance for vibration, and stood up better to water. (I discovered it even smelled better than polyester.)

    It's been a long time since I was in the biz but it sounds like you're being screwed on the price of polyester, and may be getting a helluva bargain on the epoxy.
     
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  8. Jetboy
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    Jetboy Senior Member

    Thanks for the link DavidJ. That's a lot cheaper than what I had been looking at.

    The boat will be a trailer sailer, so I suppose the osmosis issue isn't really a problem.

    I need about 15 gallons according to the plans, so with polyester at 25/gal and epoxy at 60, the difference in cost is about $500. It sounds like the polyester stinks, but makes building easier.
     
  9. DavidJ
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    DavidJ Senior Member

    Yes I don't know the intimate chemistry but I've read the same things about vinylester. When I worked for a yacht designer it was all we ever specified for FRP boats.
     
  10. PAR
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    PAR Yacht Designer/Builder

    A lot depends on your design, but polyester wouldn't be the logical choice for a honeycomb cored (or foam cored) composite build. Vinylester and epoxy would be the usual suspects, because of the modulus of elongation issue with polyester resin, not being sufficient to take advantage of the physical properties of the core choice. Not to mention the polyester laminate will be much heavier and labor intensive.

    $60 a gallon is the retail price of the resins you're looking at and obviously you've just begun your search as you can easily get 15 - 20 lots of epoxy for $45 (still retail). Have a look at Marinepoxy at Bateau.com and Progress Epoxy at epoxyproducts.com

    Epoxy is the choice if you want the strongest and lightest laminate, which in a multihull is typically quite important. If you want to save a little money, don't mind the migraine headaches you'll get, from the solvents used in polyester and vinylester resins, then use it.
     
  11. rwatson
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    rwatson Senior Member

    WD40 and Acetone are fine, I quite like them myself.

    I can even stand Polyester, but VynilEster is really evil.
     
  12. Jetboy
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    Jetboy Senior Member

    I'm leaning toward epoxy at the moment.


    Almost all of the construction is basically one or two layers of 12oz glass over 10mm core. I think I'll just do a basic roll on epoxy layup for most of it.

    The beams, I'm not sure how I'm going to build them yet, but if original require about 12 layers of various glass fabric and matting. Am I going to really struggle to wet it all out with epoxy instead of using glass? That's something I'm concerned about having never done anything like this before.
     
  13. c_deezy
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    c_deezy Junior Member

    Where are you getting your supplies?

    Around here, pails of decent poly (5 gallons) go for around $130 ($26/gallon).

    Vinylester usually falls midway in between poly and Epoxy as far as price, I think it was around $170 a pail last time I checked.

    Personally, I would go with Vinyl Ester. But it depends on where you are working also, if fumes are a concern go with epoxy.

    I would check out US Composites for prices on your resin, $60 a gallon sounds pretty high.
     
  14. CatBuilder

    CatBuilder Previous Member

    Be aware that US Composites is a nightmare to place orders from though. They not only stick you with absolute full retail, they require onerous amounts of paperwork from you to set up an account.

    We chose not to use them as a supplier after wasting many hours with them instead of building a boat.
     

  15. Jetboy
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    Jetboy Senior Member

    I don't have a resin supplier figured out yet. My intention was probably to use Resin Research products. They are around $60/gal, but that includes shipping. I haven't found any others that are significantly cheaper after shipping is included. I'm certainly open to suggestions.


    I'm building it in my garage in a residential neighborhood, so the smell could be an issue. Especially since my wife will be parking her car in the bay next to the boat. I don't think she'll be very pleased if it's really stinky.


    Catbuilder: Were you working on a small volume purchase or trying to set up a large scale revolving purchase agreement? I'm wondering if it will be a big hassle to buy a one time shipment.

    I'm also open to any good ideas on where to find the best deals on fiberglass fabric. I need about 150yds of 10-12oz.
     
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