The idea that a raw egg will rot is true but misleading; kept in the shell for a few weeks, it'll end up smelling funny--but out of the shell and at room temperature/humidity, the moisture content of the white will evaporate long before it has a chance to rot, so it's essentially fragrance-free. I believe the use of egg-white as a groundcoat/grain filler originated with violins, and I've used it for that purpose in the past with great results.