captain red Posted April 10, 2003 Report Share Posted April 10, 2003 Hi, I need info on what to use to fill the surface imperfections in the acx plywood before I glass over the hull with resin and cloth. Thank you, Captain red Quote Link to comment Share on other sites More sharing options...
Pat Mellema Posted April 11, 2003 Report Share Posted April 11, 2003 Red I used bondo autobody filler to fill in the surface imperfections. It fills in well and sands off easy if done the way it says to do it in the plans. I also used it to make the fillets on the keel. Quote Link to comment Share on other sites More sharing options...
MisterMoon Posted April 11, 2003 Report Share Posted April 11, 2003 Bondo will swell when it gets wet, sometimes with unpleasant consequences. I'd suggest instead you use epoxy filled with phenolic microballoons. It wil sand just as easy as bondo. If needed for thixoptropy, just a smidge of colloidal silica will greatly thicken the mix without adversely affecting sanding characteristics. There is also a marine version of bondo you might consider. Quote Link to comment Share on other sites More sharing options...
capt jake Posted April 11, 2003 Report Share Posted April 11, 2003 No need to fill anything more than screw holes and create your fillets prior to glassing. I also would use the microbaloon mixture. You will have to do final fairing and filling after the glass anyway. Save yourself the time. Quote Link to comment Share on other sites More sharing options...
Sailor3356 Posted April 11, 2003 Report Share Posted April 11, 2003 Wow never knew Bondo could swell when it gets wet. Boy all the years I have used it on cars and boats. Never saw a single spot that I fixed swell when it got wet. Vinyl fabric is said to be waterproof and the harding agence. Methyl Ethy Ketone Peroxide and Dimethl Phthalate are not bound by water (H2O) only the Hydrogen Peroxide and that is resolved as the agent is released to air. If you are getting swelling its from the wood around the Bondo. Now you can buy the most expansive fillers but if you don't seal the wood you will not be any better off. Just a thought.:idea: Quote Link to comment Share on other sites More sharing options...
MisterMoon Posted April 11, 2003 Report Share Posted April 11, 2003 It's not the poylester, it's the fillers that are the problem. To be fair, it's not that much of an issue above the waterline on boats that stay in the water or below the waterline on boats that are trailered. So in that sense, you are correct. Quote Link to comment Share on other sites More sharing options...
tdrown Posted April 11, 2003 Report Share Posted April 11, 2003 I have used a number of things so far. I started with wood putty, but realising that it read "easy water clean-up" means it probably will fall apart in water. I used a little plumber's putty which won't come apart in water, but it won't harden either, so it is not very usefull since it don't really stay in place if it gets touched. I also found a tube of Bondo body filler (which is not the same Bondo body filler everyone else is talking about, that requires mixing and it gets hot if I'm not mistaken). I've also been adding a little sawdust to the fiberglass resin I have been using as glue, I've only tried this on non-esential places, but I am wondering on how effective it is. I have heard of other people doing something similar, the important thing is to have it still be a liquid of some sort of amporphus solid I supose. I think I just read something about using a small ripped piece insulating fiberglass and adding resin or epoxy to it, add enough coats of liquid until the glass untill the entire thing turns from its pink to a dark red. I've also heard of people melting plastic in such holes. Good luck with whatever you'll choose, I am also using AC ply, purely for cost reasons, and I have a few holes to cover up. Oh well, best of luck! Quote Link to comment Share on other sites More sharing options...
High C Posted April 12, 2003 Report Share Posted April 12, 2003 I'll second the epoxy + microballoons suggestion. Easy to work, non-shrinking, and easy to sand. Spread it with a plastin spreader or wide putty knife. Don't dally around though, short pot life! Quote Link to comment Share on other sites More sharing options...
Frank Hagan Posted April 13, 2003 Report Share Posted April 13, 2003 Best fix: epoxy mixed with either microballons or wood flour (microballons are much easier to sand .... but both mixtures are NOT waterproof, so make sure you do this only on an area that will be given several protective coats of epoxy). Next best, and cheap: Bondo Auto Body Filler. Like epoxy and microballons, it isn't actually waterproof, and must be protected by a coat of paint or epoxy ... Mike Stevenson has a story about one of their prototypes coming apart at its Bondo seams when they did a quick test of the design (they make it pretty after the basic design is set, so didn't have it coated). Bondo is very easy to work just after its cured, and gets harder and harder as it cures. For an ACX boat you are going to glass with either epoxy or polyester resin, I'd go with Bondo. Cheap and easy. If you already have the epoxy, then that's a better way to go. But my understanding is that the hollow structure of the microballons make them unsuitable for use below the waterline unless coated, just like the Bondo. Quote Link to comment Share on other sites More sharing options...
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