Re: jb weld or epoxy?
i've got a fiberglass jon boat with holes in the transom
i need to seal it but can i use jb weld, epoxy, or resin?
JB Weld
is epoxy.
JB will work, Marine-Tex will work, Fiberglass will work (be just like the rest of the boat). Epoxy sticks best, but polyester resin (fiberglass resin) sticks pretty good to itself too, been used successfully now for decades - works great when you follow the instructions.
Many look down on fiberglass resin since it doesn't stick to other stuff, but it doesn't pretend to be a nearly universal glue like epoxy is.
One thing about an epoxy patch, you have to overcoat it with paint, varnish or gelcoat so UV doesn't break it down over time.
Should you choose epoxy as your repair material, but want to gelcoat it to match the rest of the boat - read this for a successful job.
http://www.westsystem.com/ss/polyester-over-epoxy
-- more on JB Weld and other pre-mixed resin - just for fun.
The A-B epoxy in a tube (and larger sizes) for fixing cup handles and drawer joints is the same base resin as laminating resin. It's just been pre-mixed with a filler. Marine-Tex too.
JB Weld uses a powdered metal - it's their secret to success. Others use calcium carbonate, talc, and wood flour. Mix your own and the possibilities are even greater - glass & plastic bubbles for fluffers, silica in varying micro-sizes to thicken & harden, glass (or exotic) fibers for resilience - each best suited for differing applications.
Nearly any filler added to raw resin adds a little "strength" but the way it adds it is something most people over look in making a selection.
Think of cement - add aggregate rock and it gets hard strong, add sand and it gets sonewhat strong and better leveling, add rebar steel and it holds together even when cracked. Same differences with resin additives. You can make it rock hard and inflexible, fluffed up and easy to sand, or bound internally by fibers.
For what fillers do for resins, look at the variety of applications and how fillers should be matched up.
