Another Polyester question

Discussion in 'Boatbuilding' started by wadreon, Jun 3, 2010.

  1. wadreon
    Joined: Jun 2010
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    wadreon New Member

    I am redecking a boat, and so far I am using polyester resin to 'seal' the decking plywood. Does anyone know how well this works to seal the wood completely and permenantly? I am sure epoxy resin may work better, but as for cost, It seems to be much more expensive, unless someone knows of a good product that doesnt cost as much as west systems epoxy. Right now I am using west marine poly resin, and having a heck of a time mixing it right to get it to cure right, either too long or too short. But my main concern is how well this resin works as a wood sealant. I will probably run out of the gallon that I am using, so if there is a better method I guess I would switch then. Any advice would be great.
  2. Lurvio
    Joined: Jul 2009
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    Lurvio Mad scientist

    I am using a German brand polyester and I use an old kitchen scoop to measure the resin (after testing it's volume) and a syringe for the hardener. Has worked fine so far.

  3. CDK
    Joined: Aug 2007
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    CDK retired engineer

    With just poly resin you cannot seal anything 'completely and permanently', only partially and temporarily.
    The resin lacks flexibility and strength unless you add fillers or reinforcement. Epoxy is much stronger, but the ultimate material to seal forever is polyurethane.
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    FAST FRED Senior Member

    Adding 3/4 oz mat or just surfacing tissue to the polly paint job will make it thicker and stand up to flexing and damage better.

    The best types of Vinelester resin are close to Epoxy in cost.

    One trick is to brush on a thin layer of accelerator on the wood before putting the polly paint job on.

    Helps the resin get further bonded with the wood.

    Sand with 32-40 grit to get good roughed surface area and use a vacume before painting to get all the dust.

  5. apex1

    apex1 Guest

    How much cheaper is poly resin when you have to do the job soon again?

    Use Epoxy and some glass fabric for abrasion resistance. Apply one coat of neat epoxy on the ply, wait until it kicked, then lay up the glass / ep. Seal aginst UV rays with a UV protecting varnish or paint it. PU varnish or paint do the best jobs but must not be.

  6. WickedGood

    WickedGood Guest

    Rednecking a Boat with Polyester

    A few years back I picked up a Classic Lightning designed and Built by Skip Etchell back in 1954. ( Skip was one of the premier American Boat designers and as everyone knows Americans build the best Boats, well maybe except for Noah; But Noah was a Jew and he would have been an American too if he had lived long enough) It had been stored in a basement garage in Cape Ann since the 70s or so and the wood needed to be stripped and varnished and the canvas decking needed to be replaced and doped.

    So I stripped all the hardware and went to Homy Depot and bought the heavest painters canvas cloths that could be bought with a greenback. I also picked up some Stainless Steel Staples and tried to get some Dope, but all the stores did not have any.

    So I used White Topside Paint made by Rule/Gloucester thinned with 50% laqure thinner.

    It dried tight as a drum and looked slicker N' Snot.

    No longer have the boat as I rtraded a fella for a nice deer rifle that I shot a nice deer with and made a nice Mulligan Stew that I enjoyed with an Irish Ale as I thought about what a long strange trip its been.

    Remember Beer & Boats. It may Kont be an American Invention; But We perfected the art.

  7. wadreon
    Joined: Jun 2010
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    Location: Wisconsin

    wadreon New Member

    Lets not make this complicated

    So is going to a local hardware store and picking up some polyurethane deck sealant a bad idea. This seems too complicated for what it is worth. I understand everyone has their two cents on how to do it. But there is NO need to add fiberglass cloth. And I dont need a chemistry lesson on vinaluthenides, or put the wood through a three step chemical bath. It sounds as if polyester is a bad sealant. So is epoxy a better option than polyurethane? I have looked into the cost of both. I just want it done right before covering the wood up.
  8. mark775

    mark775 Guest

    You just got advice from the guy who knows better than any of us...and you rebuked him. (" everyone has their two cents on how to do it. But there is NO need to add fiberglass cloth" ) Good luck.
  9. FlyingTime
    Joined: May 2010
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    Location: Stuart FL.

    FlyingTime Junior Member

    Use a 50/50 mixture of resin plus catalyst and denatured alcohol for your first application. Brush it on, this will allow the resin mixture to soak deep into the plywood before it hardens. Sand lightly and apply a second coat of resin and hardener only. Most minor surface scratches won't go as deep as the first application... Be sure to follow the proper ratio's for the resin and catalyst. Epoxy would be better and you'll have more time to work with it.
  10. wadreon
    Joined: Jun 2010
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    Location: Wisconsin

    wadreon New Member

    No I am not saying he, or anyone doesnt know what they are talking about, Im sure they do. I was just looking for a simple answer. As I am finding is hard to get here, I am not looking for design advice, or additional things to add onto the wood. Frankly, I was just seeing if anyone knew what worked better, polyester or epoxy. And furthermore, I didnt mean to be rude, though now after reading my last post, I did sound rude. I appreciate all advice. As others experience is how we all learn, good and bad. So I ask again.... I take it from the more experienced here, that polyester resin is not a good choice to seal wood. However, would I be making a mistake by just heading to the hardware store and picking up some polyurethane deck sealer, or would I be better off by going with a two part epoxy??
  11. apex1

    apex1 Guest

    You go better with EP, to seal / encapsulate the wood. Three layers of neat EP are the common way.
    Never use any thinner with EP! No matter what some people tell you. Every thinner weakens the properties dramatically.
    Then you MUST cover it with a UV protectant. Either paint (a good standard outdoor House paint does it), or varnish.
    UV resistant varnish is not enough, that just means the varnish itself is protected. It has to be protectant!

  12. girvin
    Joined: Dec 2009
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    Location: Vancouver Island

    girvin Junior Member

    There are epoxy's with uv inhibiters built in like resin research.

  13. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Wadreon, I think the issue here is that there isn't a really cheap and simple way to properly protect your wood. You see mother nature is always trying her best to return everything we humans make to a simpler state (read degrade).

    Apex is telling you the absolute truth. I know, it's painful to have to shell out for good epoxy at $70.00+ per gallon and good polyurethane paint goes for $50.00+ per quart plus the proper thinners and rollers and brushes and respirators and protective gear and all the rest you need to do the job.........

    You can do what you want. But I'll warn you.....stray from the advise that Apex has given you and you will learn the hard way. The reason that the experienced guys here get exasperated is that they KNOW it's costly to do the job right. They know it's not what you want to hear. They also know it's what you HAVE TO HEAR.

    I'd suggest that if money is an issue then put the boat aside for a little while and go get a part-time job. Save up enough to get what you need and then do the job right.

    You will not be sorry.....

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