Razors were first used on animals to prepare leather and to collect wool.
Then came the barbers and the evolution of different tools. The folding straight was mainly used by barbers/surgeons/dentists on the market places till XIX century. Then they opérée barbier shops.
At end of XVII century M. Perret, a french "gentilhomme" wrote à booklet on "the art of self-shaving" to encourage the gentry to do it so for sanitary reasons. The SR became a "produit de luxe" for the gentry with scales of ivory, mother of pearl or tortoise, with silver scutcheons or gold engraving.