How to prevent blisters when using polyester resin?

Discussion in 'Fiberglass and Composite Boat Building' started by Bullshipper, May 17, 2018.

  1. Bullshipper
    Joined: May 2008
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    Bullshipper Bullshipper

    Are certain blends of this base resin better than others?

    Which gel coats or barrier products best to use?

    If polyester is unsuitable, would you use epoxy or vinlyester ?
     
  2. BlueBell
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    BlueBell Ahhhhh...

    Epoxy
     
  3. ondarvr
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    Location: Monroe WA

    ondarvr Senior Member

    Not all polyetser resins are created equal, and neither are the methods used to build products from them.

    You will get different blister results, or the potential for blisters, from the build method you choose, the same resin used in one way may result in no blisters, used in a different way and the potential for blisters may be higher.

    But back to the resin end of it.

    The standard low cost GP (general purpose) resin isn't designed for marine use, it's designed to be low in cost and provide adequate performance in a range of products, frequently low cost is the primary consideration. For a small skiff or a boat that doesn't sit in the water for long periods of time it can work well enough that you probably won't have any problems, on the hull of a boat that stays in the slip you might. This will frequently be a blended resin, ORTHO/DCPD.

    A marine resin would typically be an ISO/DCPD blend, it will resist blistering a great deal better, and you typically won't have any issues. On larger boats that will live their entire life in the water you may want to upgrade from here though.

    You can upgrade to using a VE skin resin in combination with either of the two prior resins and have very good results. Most of these skin resins are a VE/DCPD blend, but ther are straight VE's

    VE barrier coats behind the gel coat can help eliminate blisters with any of the listed resin types, when used correctly the chances of having a hull blister would be very unlikely no matter how it was treated when these products are used.

    Most marine grade gel coats will hold up just fine below the waterline.
     
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  4. Bullshipper
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    Bullshipper Bullshipper

    Thanks so much.
     
  5. BlueBell
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    BlueBell Ahhhhh...

    No sweat.
     
  6. Bullshipper
    Joined: May 2008
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    Bullshipper Bullshipper

    Ondavr,
    My supplier in Mexico will blend to my requirements. Is there a particular blend spec or brand you could suggest?
    I am looking at producing a smooth surface for the plug and mold first.
    I will then make a hull and off course this is the item that I want to be blister proof, so I am assuming I will need one product that surface finishes well for the plug and mold part, and another for the boat that will be immersed more.
     
  7. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Where are you located and what supplier are you working with, this makes a difference in what products may be easy to find for the tooling end of it.

    Also, the size and type of boat will determine the resin choice, a low cost 23' panga may require the cheapest resin you can buy, where a larger high end sport-fisher would need the more expensive products.

    Surface profile (quality) also comes into play. One reason for the blended resin is to improve the surface profile of the finished part, DCPD doesn't shrink as much as other polyesters, so the finished part may look better. In the states it's also used to lower the emissions of the resin because less styrene is needed, this may not be required in other parts of the world.
     
  8. Bullshipper
    Joined: May 2008
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    Location: Mexico

    Bullshipper Bullshipper

    I am 4 hrs south of the MX- Arizona border near the port of Guaymas, Sonoraand may have to import what I need as stocks her are very limited.
    There is a Richland (sp?) resign factory but I believe Owen Corning has closed their operatons here. I can get 3m products as well as the Baltec foams also out of Guadalajara. Don't know the brands of the tooling gel, release agents. but whenI asked for fiberglass tape they said that was impossible.

    This is a 28' x 10' power cat to be sold in the tates but my goal is to just build the plug and mold here, then export those to the states to vacuum infuse with a boat shop in S California.

    So I planned to build the plug using poly, and use DCPD for the mold, unless instructed other wise. What I need is a couple of product so that I can download the technical data sheets to see if the supplier here can match that, and if not, go to Composites One or Gulfstream Composities to supply what I need to import.
     
  9. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    When in MX I work with Alfonso at Composites One, they can get just about anything you want.

    Straight DCPD resins are very brittle, so they aren't used often, but when blended with something else they perform better. If you plan to make only a few boats per year the resin choice is important, but not to the same degree as when the molds will be cycled frequently. Tooling resins hold their shape better, and hold up longer in production. Build the mold strong enough to hold up long term, otherwise you'll be repairing it constantly and the finished parts won't look good without a great deal of attention.

    For a one time use plug the build method isn't that critical, but if you want it to last it needs to be built fairly sturdy, unless enough glass is used building the plug it will typically self destruct when trying to seperate the mold from it.

    Most tooling now is CNC cut foam with a polyester primer as a finish, but a wood shape may be easier to build in MX, it just depends on the type of industry in the area. Duratec makes a full line of plug and mold building products that are easy to use.
     

  10. Bullshipper
    Joined: May 2008
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    Location: Mexico

    Bullshipper Bullshipper

    Excellent, they are a real supplier.
    I sent an inquiry in to Composites One to see if I can get his (Alfonso Espinosa, Mexicali) number.
    Really appreciate your help!!!!!!
     
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