Steve, Epoxy (West's or others) provides a superior secondary bond over polyester. West Systems is often used by DIY boat owners because of their very helpful instructions and guide on their web site and the availability through retailers.
Also, polyester based resins and fillers absorb moisture faster than epoxies. (Our company uses both in aerospace and mil-spec components that are tested for suitability in a wide range of exposures.) For short term repairs polyester based fillers and resins will work fine. Over 10+ years epoxy based resins and fillers will provide a better bond and resist water intrusion/absorption better. Both need to be protected from UV. Martin DeYoung Calypso 1971 C&C 43 Seattle [Description: Description: cid:D1BF9853-22F7-47FB-86F2-4115CE0BAF2F] From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Steve Thomas via CnC-List Sent: Thursday, February 26, 2015 10:15 AM To: Josh Muckley; cnc-list@cnc-list.com Subject: Re: Stus-List Need Recommendation for Tool to remove balsa core from drilled hole - resins etc I bought a used Natty dodger for my boat and am faced with the same task for the 30+ holes to install the Lift-the-Dot(r) fasteners that it requires to fasten the canvass to the deck. I did try to counter sink holes in the gelcoat and screw into the top fiberglass layer underneath, but that turned out to be a disaster. I have done lots of through bolting for various things over the years without difficulty, but this was my first experience trying to use self tapping fasteners (look like wood screws) in the deck and it was not a positive experience. The gelcoat is very thick in places, and in spite of my attempts to counter sink the gelcoat, often as not the screw chips out a huge flake. Removing the canvas female fastener from the deck mounted pins can take some force, and the screws pull out of the thin top layer of fiber glass. So I concluded after several failures that I need to stop what I was doing and use the drill and fill procedure. Then came winter. In all of these discussions about drilling and filling over the years, everyone defaults to using West System epoxy resin to fill the areas needing reinforcement. What is it about this product that makes it so superior? Why not use a polyester resin? - at least gelcoat will stick to it. Like most of us older guys I had experience with automotive body fillers in my younger years. They are all polyester. What is wrong with using that? Some of the Lift-the-Dot(r) fasteners are difficult to release and I don't know how to fix them. I have been thinking about changing over to the flat, 1/4 turn fasteners that are commonly used now. Is it a practical solution? Has anyone tried this? Spring project. Steve Thomas C&C27 MKIII
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