FN used a combination of shellac and oil varnish (perhaps something like the old spar varnish)"hand applied"--which I suppose means rubbed on and rubbed down on the early Browing Supers. I don't think you'd want to set your coffee cup on a true French polish and when it cracked, you'd see worse problems of "permeability" than you're ever going to see with boiled linseed with or without driers.

jack