Michael Lachowski wrote:I've never used epoxy that was too thin when wetting out cloth for vacuum bagging. Less epoxy is generally better provided it has suitable mechanical properties. Now if you're just gluing things, then epoxy can be too thin.
Avoid extra-long cure epoxies. I used some 3 hour stuff that was very thin, but it remained tacky for days and took a couple of months to completely harden (i.e. 'til the test pot was cleanly drillable).
Typically chemical reaction rates double every 12 or so degrees F. Make a warm/hot box out of basic stuff like foam insulation or multiple layers of cardboard and stick a 100 w light bulb in it. You can easily and safely get up to 100 F and most any adhesive will cure out much faster and quite hard. Use duct tape, the handyman's friend, and you can fold it up for storage when not using it.
Epoxy resins have a tendency to soften when heated, even if they appeared to be fully cured at room temperature. The inside of a car or truck can get pretty hot when sitting out in the sun for a bit, as can garage roofs. I always make it a point to heat anything I need to at least 10 F higher than the part will ever see in use. Wrapping a wing or a fuse in black plastic and sitting out in the sun for a couple of hours will cure anything as well as needed. Make sure these parts are not under any sort of load when going through a post cure cycle as things like wings and fuses will distort if subjected to loads of most any sort. After a part is cured out at some high temperature, it will not resoften when reheated to that same high temperature. It's just the nature of epoxies to do this, other adhesives don't go through a similar heat post cure cycle.
Cheers,
Bill
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