After the epoxy is fully dry, this is how it needs to be prepped for body filler or primer to go on top of it.
♦️The first step is to use a scotch brite pad and scuff it. This first step is a way to make sure that everything is at least scuffed, incase anything is missed sanding it.
♦️Once it is scuffed, it can be sanded with about 100 to 120 grit. This can be done carefully with a d/a sander, or by hand. Try very hard to not sand through the epoxy.
♦️Then, blow it off good and clean very good with wax and grease remover.