Have you checked the color and viscosity of both cans? Could they have sold you two resins or two hardeners with one of them mislabeled. It can happen when goods get repackaged into smaller containers. Especially if it is a one to one ratio.

: I'm restoring a patuxent 19.5 that I built about 10 years ago. Previously
: I've used MAS and West Systems products with good results. This time I'm
: using TAP marine epoxy. So I mix up a batch with graphite powder mixed in
: and coat the bottom. It's about 60 degrees, and the instructions say
: that's OK - barely. Come back the next morning and it's still wet. What?
: So I turn on the furnace to 80 and go away. 10 hours later it's still wet.
: I go to TAP website and they say that it shouldn't be applied below 77
: degrees! Nice! So I try another coat in a pre-warmed shop with a little
: extra hardener. Same results!

: I call TAP, and they suggest another coat using the quick set catalist. I do
: so, and get a few patches of firm set, and most is still wet! At this
: point I'm disgusted and set the kayak on a rack for a week.

: It's still wet! What should I do (besides never get within ten feet of TAP
: epoxy ever again.)