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Thread: pre-coat hull?

  1. #1
    SteveMason Guest

    Question

    I have recently read about a new practice of precoating the hull with epoxy before apllying the fiberglass cloth. The method involves applying a thin coat of epoxy and allowing it to cure for 24 hours before beginning layup of the cloth. The article claimed that there were fewer problems with cloth starvation and bubbles. Can you comment on this? Is this something that is now being commonly done. Oh, yes, I am using the East System epoxy. Thanks!

  2. #2
    Andy Tischendorf Guest

    Thumbs up

    Originally posted by SteveMason:
    I have recently read about a new practice of precoating the hull with epoxy before apllying the fiberglass cloth. The method involves applying a thin coat of epoxy and allowing it to cure for 24 hours before beginning layup of the cloth. The article claimed that there were fewer problems with cloth starvation and bubbles. Can you comment on this? Is this something that is now being commonly done. Oh, yes, I am using the East System epoxy. Thanks!
    Steve,

    I just recently finished glassing the outer hull of my project, and I did what you described in your post. I thought it went very well. I did not have any problems with bubbles or cloth starvation. I used the West system however, with extra slow hardener. Hope this helps.


  3. #3
    Join Date
    Apr 2000
    Location
    Cedar Rapids, IA USA
    Posts
    11

    Post

    I am finishing my second cedar strip kayak, both of which were pre-coated. In my opinion, there are several reasons to pre-coat. The first is to seal the wood. This prevents any outgassing from occurring. It also fills any staple holes and hairline cracks. Another thing that it does is it gives the wood some "tooth" which prvents the fiberglass from shifting around as you try to wet it out. Incidentally, you should also pre-coat any wood surfaces before gluing them together with epoxy. I use MAS slow cure epoxy. There is also a product called CPES which is supposed to be a very thin epoxy product specifically made fore penetrating and sealing. It is supposed to penetrate much deeper than regular epoxy. I have not tried it yet, but I have heard a lot of good things about it. I am going to give it a try on my next project. Good luck on your project.

  4. #4
    Ric Steeves Guest

    Thumbs up

    Originally posted by SteveMason:
    I have recently read about a new practice of precoating the hull with epoxy before apllying the fiberglass cloth. The method involves applying a thin coat of epoxy and allowing it to cure for 24 hours before beginning layup of the cloth. The article claimed that there were fewer problems with cloth starvation and bubbles. Can you comment on this? Is this something that is now being commonly done. Oh, yes, I am using the East System epoxy. Thanks!
    If this is the first time you have done glassing this would be a good approach. You would have to sand the epoxy before doing the next coat however. On the other hand if you want to wet out thru the glass East System is relatively thin and saturates the cloth easily so you won?t have much of a problem with bubbles. You should also watch for dry spots were the cedar is absorbing extra resin. Besides who needs to sand one more time.
    Ric



  5. #5
    Join Date
    Apr 2001
    Location
    monomills
    Posts
    2

    Cool precoating

    I would recommend pre-coating as you are giving an even seal to the wood. I find I have enough to worry about while glassing without having to control how evenly the epoxy is soaking into the wood which effects colour. There is no need to sand after pre-coating as long as the glass ) or second coat ) is applied within 24 hours.
    Good Luck
    Jim

  6. #6
    Join Date
    Mar 2001
    Posts
    399
    If you are using MAS Slow hardener at room temperature you can recoat after 24 hrs without sanding, but with East or West, you will need to sand after 8 to 12 hrs.

  7. #7
    Join Date
    Apr 2001
    Location
    Orange County, CA
    Posts
    1

    Pre-coating

    I have just finished planking and mounting the outer stems of my Rob Roy, I am a 1st time builder, and have never done any glassing.

    My intentions are to apply all coats and glass on the same day as suggested in the original CanoeCraft book to create the ultimate bond.

    The pre-coating of the core sounds like a good idea. But can I apply the glass cloth and the wetting coat while the pre-coat is still tacky? I'm using East or West (can't remember what came with my kit from Naohs as the standard epoxy)

    Also, where can I get a copy of the article referenced in the earlier posts regarding pre-coating?


  8. #8
    Join Date
    Mar 2001
    Posts
    399
    I have found that if you lay light weight glass (6 0z) over tacky resin it is harder to smooth out before applying more resin. This can result in air bubbles or opening gaps in the weave of the cloth as you try to move it. The glass will slide easily on a dry surface. If you want to recoat, the safest is allow the resin to cure and sand the next day. Then do your glass and covering coats all I one day

  9. #9
    Join Date
    May 2000
    Location
    Grande Prairie, AB CA
    Posts
    5
    I have always done a saturation coat prior to glassing. Regardless of whether it's cedar strip or Okoume, the saturation coat seals the surface and will allow any high spots to appear before you glass. I normally sand the hull after the epoxy has cured for several days to ensure a smooth, even surface.

    I tend to use less epoxy this way and it also gives you an idea of what the finished boat will look like. Good motivation when you are going through the sanding stages prior to varnishing!

  10. #10
    Join Date
    Mar 2001
    Location
    Iowa
    Posts
    4
    I agree with Don Maurer. We precoated the outside of our Redbird and it worked out great. If you use the MAS, you have 24-36 hours to follow up with the next coat and still get a chemical bond.


 

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