I'm going to apply epoxy to a wood piece then primer and paint.Spray paint would not be my first choice for waterproofing wood. I would actually use epoxy to seal it and then paint over the epoxy to protect the epoxy from UV and to make it look nice.
I typically do one side at a time. 24 hours apart.
Is it possible the tacky you feel is just amine blush? I know west system must be washed before sanding or recoating.