How Strong is Epoxy When Used as an Adhesive?

I have used a paintstripper heat gun to remove epoxy. But you are talking of seriously hot. If there hadn't been epoxy on the ply it would have caught fire. Erm........well, some bits did.

Some one posted recently about chopped strand mat not being suitable for epoxy. That you should use proper woven epoxy tape.
 
The fact that you can use a hot air gun to remove epoxy is in my opinion it's best quality. /forums/images/graemlins/grin.gif

I know that the heat doesn't have to be hot enough to start burning the wood to melt the epoxy. But it's not far off.
 
A bit worried about 'gluing' the heater in place. What happens if you need to take it off again for repairs etc?

Understand not wanting to through bolt on the transom, but I would have thought you would do better to use 'blind' bolts on the plywood pad, so that you can actually bolt the unit on.

You can also design the mount in such a way that the glue bond between the pad and the boat structure is not taking the full weight. Fort example, make a shelf that is permanently attached to the boat - perhaps glassed in, with the grp moulded to provide support for the weight. The shelf can be drilled to take the Eber fastening bolts with ease, for susbsequent removal.

As my yard boat builder says: 'its a boat, if something can cause problems - it will!' Dont build in more problems than you have to!
 
Tangomoon said/ epoxy won't take to plastic
This is not my experience as I stuck my engine to a plastic hull with epoxy, about five thousand kilometres back. The molecules of epoxy are smaller than of GRP resin and so penetrate well and make strong bonds. It is GRP resin that does not adhere to epoxy, because the molecules are bigger and do not bond in with the smaller epoxy molecule structure. As long as GRP is old and rough then epoxy will stick like hell to it.
 
Lakesailor said/ chopped strand mat not being suitable for epoxy. That you should use proper woven epoxy tape.
I heard the same and because chopped strand mat had a coating that was meant to react with the GRP type resin but that epoxy would not react and thus the adhesion would be limited by an barrier. I was told to use glass tape or woven roving with epoxy, which I did . . . mostly.
 
From memory, if the temperature's below about 5 C, epoxy stops curing. If the low temperature goes on too long there will be problems with final strength, but I've recently been epoxying in daytime temps of 10C night around 5C. It does go off, but not completely overnight, which can be useful, as you can add more epoxy and it bonds chemically, not just mechanically, so is stronger, and there's no need to sand.

BTW, it's VERY important to support epoxy while it's going off. It has approximately zero tack. I built up a patch of several layers of glass cloth & resin to fill a hole in Jissel from underneath. It looked fine when I left it, but an hour later the damn thing was on the ground under the boat /forums/images/graemlins/frown.gif
 
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