Sealing/curing laminating polyester?

Discussion in 'Fiberglass and Composite Boat Building' started by andysailor, Feb 27, 2019.

  1. andysailor
    Joined: May 2017
    Posts: 65
    Likes: 2, Points: 8
    Location: Sweden

    andysailor Junior Member

    I'm building new countertops at the moment. If I apply non waxed polyester resin....will it cure when I pour the epoxy on top even if it is days between...or shall I apply waxed polyester and sand it instead ..before applying the epoxy?


    ....I'm used to work with waxed polyester...somebody in the boatyard said it would cure if misting water on the non waxed one....Would it?
     
  2. ondarvr
    Joined: Dec 2005
    Posts: 2,081
    Likes: 184, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    You can’t pour epoxy over polyester in that way, you can only apply it to a fully cured and prepped surface.

    Water brings the cure process to a complete stop, so misting water on the surface is exactly what you don’t want to do.
     
  3. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,902
    Likes: 336, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    You could try coating it with PVA mould release, then wash that off thoroughly, later, before applying the next coating. Unless ondarvr contradicts that, he'd know better than me. I guess you'd know if it was tack free after that process.
     
  4. andysailor
    Joined: May 2017
    Posts: 65
    Likes: 2, Points: 8
    Location: Sweden

    andysailor Junior Member

    Yeah I know about PVA but it is hard to find in central America.

    Ok...So the polyester won't cure if sealed from the air with epoxy? Or is it a bad adhesion for the epoxy? The epoxy is just to be poured to make a cool effect.
     
  5. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,902
    Likes: 336, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    I have also heard that it is no good putting epoxy over tacky polyester, and ondarvr is well versed in these matters. There may be something else you can paint over it with, that will wash off easily.
     
  6. ondarvr
    Joined: Dec 2005
    Posts: 2,081
    Likes: 184, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    The chemistry of the two are not compatible unless fully cured, there can be zero bond and/or an inhibited or no cure situation when one is used over the other.

    Always allow for a complete cure, then clean and sand the surface, this goes both ways.
     
  7. Sparky568
    Joined: Jan 2017
    Posts: 86
    Likes: 4, Points: 8, Legacy Rep: 10
    Location: Northeast USA

    Sparky568 Junior Member

    One trick I use for a finish cure as I don't like adding wax or PVA is cover the last coat of PE with wax paper. It will inhibit the air contact and if your dealing with a flat surface placing something with a smooth surface over it like MDF or Melamine. Think of it like a reverse mold.

    You'll retain some wax on the surface when you peel it off so a good sanding and cleaning with acetone will be required as any final preparation would.
     
  8. andysailor
    Joined: May 2017
    Posts: 65
    Likes: 2, Points: 8
    Location: Sweden

    andysailor Junior Member

    Yeah I hav heard about the wax paper and celuphane...good idea.

    For some shelves I'm making...I have nidacore honeycomb. Formica on both sides....can I glue the Formica to the honeycomb with polyester which then gets encapsulated and cure?
     
  9. ondarvr
    Joined: Dec 2005
    Posts: 2,081
    Likes: 184, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    Polyester resin isn’t a good glue, and I have no idea how well it would bond to Formica.

    As for the cure, it would cure correctly, no wax, PVA or anything else would be needed
     
  10. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,902
    Likes: 336, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Formica is largely melamine, I think.
     
  11. ondarvr
    Joined: Dec 2005
    Posts: 2,081
    Likes: 184, Points: 63, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    The side of the Formica that you bond to has a surface treatment for better bonding, but I don’t know how well it would work with polyester.
     

  12. Mr Efficiency
    Joined: Oct 2010
    Posts: 7,902
    Likes: 336, Points: 83, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    He might experiment with a small sample.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.