try normal wax, meaning the yellow beeswax, it never gave me problems, for a shiny final product can be a little too soft to reach a good shine, a mix with paraffine will make it more dry, in the past ive used even floor wax, the kind for marble that has a lot of body, and worked fine.
To avoid wrinkles give latex a try, and for stuff the size of a seat or a paddle flexible molds are the best.

When you prepare the mold use the same techniques you would use to repair a car body panel, car products are quite good for this, the whole suface is then buffed to a shine, if theres even a minimal scatch or it disappears or you will see it, on top of that is polished coats of wax over polished coats of wax and if you use powertools to buff be careful not to burn the wax or the product will stick.

: I would love to find a way to do it with out wrinkles. The problem with a
: shrink material is that the male mold has indentations in the crotch area
: and shrinking would bridge that. That's why i used the Vaseline which is
: sticky enough to hold the Seran wrap in place. One time I tried auto wax
: and put on several coats and the last coat was literally smudged on thick.
: I let the epoxy/glass harden over night. That was my first experience of
: panic since I could not get the seat off the mold. The tinniest fissure or
: imperfection in the mold will trap a drop of epoxy which turns to stone
: and the casting is locked on unless you "break" it free. I
: thought my mold was as smooth as glass too.