I'm experimenting with different 2-part epoxies. Recently, I dipped a bait, 5 times into propionate to seal it, allowed to dry each time, the waited a couple of days before I got around to priming. I primed the bait with a white primer (auto-air) then I mixed up an batch of Eager Plastics Crystal Clear 202, an experimental 2-part epoxy I'm trying out. Anyway, I measured the 2 parts by volume on a scale, mixed it up, applied the mix to the lure with a plastic bristle brush and then put the lure on a turner. After the first application, there appeared to be significant shrinkage, but I noticed that there were some areas that were still sticky and others that were completely cured.
Just messing around, after I got finished applying to the primed bait, I took a little of what was left over and applied it to a bait that had only been dipped in propionate. The propionate only bait, after adequate cure time was still completely sticky all over.
At first, I thought maybe I didn't mix it up enough, but since some of the baits was hard (and all of the remaining epoxy in my mixing cup hardened), I don't think that was the case. I also thought it could be some surface contamination, but because the bait just sealed with propionate and finished with the 202 didn't cure at all, I'm thinking there is some kind of compatibility issue with the 2, or maybe some solvents in the 202 or leftover acetone in the prop that could be causing the problem. A second application of the 202 on the same bait produced the exact same results.
This was my first trial doing this, and a possible solution may just be to clearcoat the bait before adding the finish. But I wanted to send out a forum and see if anyone had any other insight that might help.