Sensei and Speed, I was not saying anywhere that you are wrong and, as I said, there are applications where HEAT CAN BE REQUIRED as when I worked at Hexcel where nose radomes, farings and other aviation parts are made with prepregs and honeycomb. What I was disagreeing on is the statement that HEAT IS REQUIRED FOR A FULL CURE. I specifically mentioned West System due to the fact that, as Propworm pointed out, it does not need heat to cure to full strength as Speed stated in an earlier post. It was, in fact, formulated for marine use on full sized boats in conditions that are far from optimum for other epoxies. I've used it in sub 60 degree environments and it not only cured, though slowly, it was stronger than the wood it was used to bond. The fact that the manufacturer's website says not to heat to over 120 in liquid form attests to the fact that heat isn't desired unless you get below the recommended heat range for the hardener being used. To take it one step further, it is a common practice in boats to heat an epoxy joint to weaken the epoxy to facilitate separation of materials bonded with it which contradicts the use of heat being needed for a proper cure. One last point, I use West Systems to build R/C hydroplanes as well as aircraft. While my boats won't be doing snap rolls and hammerheads, they are subjected to a pounding and G-loads that aircraft will never experience while running at 60+MPH. Try subjecting an aircraft fuse, R/C or full sized, to the torque and vibration of a engine running at 25,000+ RPM and the opposing torque of a spinning surface drive prop, while at the same time pulling 3+Gs across two geometrically opposed two square inch areas with the forces applied in opposite directions while slamming against the water's surface and see if it holds up. That's what my 14 pound scale boat endures every time I put it into a corner. The hull has to endure the twisting of the engine torque with the reverse torque of prop blades hitting the water while the hull also is getting pulled in opposite directions at the point the turn fin and rudder brackets are attached on the transom and sponson transom. This is what fully cured West Systems epoxy must endure during a three minute mill period and five racing laps per heat with a possible 6 heats being run in a single day while normally sitting in the sun when it's not on the water. That is a lot of stress for the epoxy to handle. One more thing, for the record, the water is never smooth