A method of strengthening hair in need of strengthening includes the steps of applying a hair swelling component to the hair and applying a cationic polymer that is the reaction product of a lower dialkylamine (C.sub.1 -C.sub.3), a difunctional epoxy-type reactant and a third reactant selected from the group consisting of ammonia, primary amines, alkylene diamines having two to six carbon atoms and polyamines to the hair.
