I had been using the finishing/laminating type for foam wing skins, but it gets pretty brittle. The West Systems type (I would tell you which one, but Uncle Jimby just gave me samples from the gallon can be bought) is just about as thin but doesn't heat itself very much, and is far more tenacious, and has a very good working time. Sheeting a foam wing with the finishing type is a race, mix it, pour it out into a flat container to reduce the self-heating effect, and slap it on there fast before it begins to set. Left in a cup, it gets noticeably thicker in maybe 15 minutes, spread out maybe 45 minutes. No problem with the West systems type, it gets only vaguely warm and a cup of it will remain almost unchanged for an hour or more and could probably be worked at 2 hours. It takes a lot of the uncertainty out of the process, you never have to worry about how well it was covered and whether the penetration is correct. http://www.westsystem.com/ss/hardener-selection-guide/
I like west system too. I have some left from building a canoe, although it is several years old now it seems to work fine still.