I like, and use Imperial Sizing die wax by far the best for all of my case forming and sizing, includingneck sizing. I touch the wax "lightly" to put a film of it on my finger, and then i lightly wipe my finger across the mouth of the case... After a couple cases, your finger builds up just the right amount for the job, and i can notice the difference when sizing. (don't use too much)

I don't worry about what little it leaves in the neck...as it's such a light film that i've never had a problem with it, but it wipes off very easily if that's what you want.

DM