[oldred]

I ran out of Feather Fill G2 over the weekend but I had an old can of Slick Sand(about 1 1/2 yrs since it was opened but it was sealed good). It appeared to be ok so I mixed as usual and applied two coats but it did not seem to want to set up so I moved it out in the sun but still it would not cure out. I suspected the hardener was old so I tossed it and opened a fresh tube, it was unopened and best I can make out on the tube it is less than 6 months old. I sanded, or best described as grubbed, it off the fender and resprayed with the new mix but it STILL will not set up and I have that mess to remove again! The Slick Sand was stirred thoroughly before adding the hardener so what's happening here? Is the Slick Sand too old? Is it still the hardener? I will not use anymore out of this can but I would like to find out what is wrong here to keep this from happening again.

[baddbob]

It's the hardener or low panel temperatures that caused it not to cure. Been there myself and hope it never happens to me or anyone else again. The mix ratio for polyester primers needs to be an average for these products to work well in all climates from New Mexico to Alaska. Lately it's been cool around here and the shop might be 70 with the heat on but the panels are much less so I boost the panel temps up with a heatlamp prior to spraying any polyesters, and if I feel the hardener is getting old I add 50% more MEKP to the mix.

How warm did your panels get in the sun? If temperature was good then the hardener is going bad or maybe you got a bad batch.

OR, if the polyester was sprayed over a soluable 1K product this will also delay the cure, if you shoot it over epoxy before it has locked up good this will also delay the cure-this is all about solvent absorbtion.

[oldred]

I bet it was the epoxy as it was only about 3 hrs curing time before the Slick Sand, didn't know that was a problem. I went back and dug the mixing cup out of the trash and sure enough it seems to have cured out ok in that but then it has been a couple of days so I am not sure if more time would have solved the problem, too risky to chance. I know better than to rush something because it seems to take longer every time but at least I have learned something here, thanks