There's a lot to learn about the various fillers which can be used for epoxy. For general purposes you can just go with wood flour filler for everything, but you can save weight or increase bonding strength and abrasion resistance better if you occasionally use fillers other than wood flour. (Then be careful that you like the color of those other fillers - some of them cure white, some cure with a slight purple tint, and so forth.) Suggestion: get one of the manuals from System 3, or from West Systems or from MAS epoxies and read them carefully. Better yet, get all three manuals - and read them! For example: Microballoons make a very soft epoxy putty, good for resurfacing and sanding, but they're no good at all for bonds which require strength. Cabosil makes a very strong bond, but it's devilish hard to sand, and you're likely to sand away a good bit of wood instead of the excess epoxy. Wood flour is a good general filler, of moderate strength. "Kitty hair", which is tiny fiberglass fibers, makes a very strong bond. And then there are the several fillers marketed by West Systems, each of which has its own properties, well described in the West brochures and on the cans of filler. You can mix different fillers to get an effect intermediate between the properties of any two fillers, just as you can mix "fast hardener" (or "slow hardener") and "regular hardener" to get intermediate curing times. Sanding between coats of epoxy: - If your're adding a second layer of epoxy to one which is cured or partly cured (careful - why are you doing that??) it will bond okay **provided there is no waxy outer layer** to that first layer of epoxy once it's cured. Wash the first layer down with vinegar, rinse with water, then sand lightly to be sure the waxy outer coating is all removed. You can't always see or feel that outer coating, so it's best always to wash down and sand between coats. Sanding also provides little irregularities which help the second layer grip well.With fast hardeners and in warmer temperatures, there's almost always some of that waxy outer layer. With slower hardeners, it's less likely to occur. But wash and sand anyway. And as I said, there's a lot more to it than that. Bill Hansen *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:35 PDT