Thickened epoxy topcoat

Discussion in 'Fiberglass and Composite Boat Building' started by gtflash, May 17, 2015.

  1. gtflash
    Joined: Jun 2006
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    gtflash Senior Member

    Anyone had any success at thickening epoxy enough to act a bit like polyester topcoat, as I haven't had much luck. With silica it's either too thin and runs or too thick and won't roll or brush at all.
     
  2. gonzo
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    gonzo Senior Member

    You can simply buy epoxy paint. Silica alone will be too sticky and leave brush marks. You can mix some lightweight filler to the silica to make it smoother.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Epoxy is never used as a topcoat, because it's not UV stable, so it's always over coated with something that is UV stable, such as paint or varnish. A hardened outer coating, like thickened epoxy can have some advantages, such as impact and abrasion, but it'll still need something over it to protect the epoxy from UV damage.
     
  4. SukiSolo
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    SukiSolo Senior Member

    Quite a few commercial dinghies use a polyester gelcoat with an epoxy FRP build. So you can put polyester gelcoat on epoxy. Be very careful if moulding, as there are bonding issues between the two resin systems if the correct procedures and binding coat(s) are not used. If you intend to mould, I'd get hold of the resin manufacturers and seek their advice.

    If you are looking to (over)coat some new work or a repair, just clear coat with epoxy, let it cure fully, abrade and spray, roller or brush the gelcoat. You will find that painting with 2K is much simpler and very nearly the same for durability.
     
  5. gtflash
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    gtflash Senior Member

    Thanks gents

    It is for the bilges. The actual bilge and a replacement bulkhead. Laminated in epoxy and biaxial glass. Certain areas could do with a light fill before the prettiness but access is so limited I can now only get at it with a long pole since I have put the deck back down. I got stuck in the bilge once and I am not keen to go back down there after being rescued legs first out of the hatch
     
  6. gtflash
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    gtflash Senior Member

    Epoxy paint seems a good solution. Is it reasonably thick? I have heard some people use garage floor epoxy paint?
     
  7. SukiSolo
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    SukiSolo Senior Member

    In the UK there are several epoxy marine 2K paints intended for use as a primer undercoat or internal bilge paint. The enhanced solids content makes them a bit more durable than just clear coating. They are quite 'thick' and should be used as mixed (perhaps a trace of thinner on bare wood), with I would say at least two coats for maximum protection on internal bilge applications. Different manufacturers may use different mix ratios and be careful with the thinners as it is not quite the same as the standard cellulose type ie don't thin with this type, use the correct one IF needed.

    I've used them for buoyancy tank internal coating(s) without any problems, as well as external hull first coat primer over epoxy sheathing. As PAR says, anything that gets sunlight requires further UV protection.
     
  8. gonzo
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    gonzo Senior Member

    I used Devoe epoxy on bilges and enginerooms for many years with success. Nowadays, there is a large variety of companies offering epoxy paint, which are probably similar.
     

  9. Pericles
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    Pericles Senior Member

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