YOur mistake was using an over the counter resin system like
polyester or isothalic.  MEKP is nasty stuff for the amatuer and
those store resinshave additives to make them have longer shelf life
and that translates into weaker bonds and the incomplete curing you
speak of.  Most likely, you didn't use enough catalyst(MEKP) and it
may never fully set up.

I would start from scratch and either use a good quality
epoxy(Gougeon Brothers, System 3 etc.) and then your repair will be
stronger than the rest of the bumper.  Ask Mike Cullom about my
kevlar and Gougeon Brothers repair.

DM&FS

At 11:54 AM 8/25/2007, Jeff Lincoln wrote:

>Ok so I finally got around to fixing my cracked bumper. Problem is I don't
>think I mixed enough of the hardening compound with the other stuff. So it
>has been two days and it is still a bit tacky. So tell me is this stuff
>going to set eventually or did I screw it up completely? If I did screw it
>up what can I do to fix it - just sand it all back off?
>
>I tell you this was my first adventure in fiberglass/bondo - it didn't go
>real good. Oh well I am just hoping it can be fixed or undone in some way.
>My prep work was beautiful though - I love the Dremel!
>
>--
>Thanks,
>
>Jeff
>90' Carat (Grover)
>86' (We call this one Parts)
>85' GL (Preparing for reanimation)