I like to rebuild some shrunken areas with Magic Smooth. Works great on top of heads like Walleyes, Bass, etc.. But sometimes I find it has sagged or run afterwards. I'll spend hours rebuilding the heads on a batch of fish with Magic Smooth, put them a way only to come in the next morning to find the dang stuff sagged away from where I put it, of course, by then, it has set up hard. Swearing ensues. This will happen with one mixed batch and not another. I can only guess it's because I didn't get an accurate 50/50 mix. Anybody else experience this? Is it too much hardener to too little resin? Or Vicey versy? Been using the stuff for years but sometimes this happens and I really get PO-ed at myself when it does.