Monday, January 25, 2010

Epoxy coating and framing bulkheads

I'm epoxy coating all of the hull components before assembly. It's much easier to get a smooth run-free coat while the ply is horizontal. A lot of the sanding will also be done before the parts go together.  Michael Storer recommends skidding a foam roller to smooth out the epoxy.  It worked so well that I used it to spread and smooth the epoxy. No need for a squeegie. It lets yo put down a very thin uniform coat which does not seem to trap bubbles and does not run much.  I did the interior faces of the buoyancy tank bulkheads first to practice on parts which will be hidden. I read somewhere that if the air temperature is rising significantly during the epoxy cure, bubbles can form as air trapped in the wood expands. I tried this on one piece by coating in the morning and sure enough it's the only piece I had any bubbles in.

The areas where framing is bonded on are masked.  I'm not sure this is necessary as the secondary bond between cured and scuffed up epoxy surfaces is really strong.



After the 3 coats of epoxy cured I glued framing to the bulkheads. To keep bugs and dust out of the wet epoxy I'm putting the pieces inside our van and closing it up. I can't do this with the mast and it's a constant battle with the bugs. Why do these things like wet epoxy so much??



In order to minimize waste I cut the rollers into 4 quarters.  Each quarter can be flipped over and used twice if you don't slop epoxy all over it during the first use.



 I spread the leftover bit of epoxy from each coat on the underside of the fore and aft seats which will never be seen so any uneven epoxy is not important.



Total time to date:  131hrs

6 comments:

  1. Hi Simon. I love your work so much, I'm using it as my primary supplement to the plans. Brilliant plan having the undersides available to use the excess epoxy on.

    I, too, plan to pre-seal as much as possible. Why not glue the frames in place first then do the triple coating? Would they get in the way much? They need coating too, right?

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  2. Hi Dave,

    Thanks for the nice comment.

    The hardest areas to sand epoxy are the corners and joints so my thinking was that I'd coat and sand everything before assembly, including the frames. The flat ply parts are also much easier to sand with an orbital sander when there are no frames attached. The assembled parts came out looking great. I masked some of the parts during assembly to control the epoxy squeezout.

    The interesting thing is that now that I have varnish down over the ply I'm wondering if getting the epoxy perfectly smooth was worth it. This is because the varnish is not sanded between coats as that would have taken close to forever. The varnish is therefore not perfectly level. The boat looked better in epoxy than it does varnished

    I wonder what it all would look like if I had assembled things first then epoxied. I have a feeling it would have been much faster with not a lot worse results.

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