The process of claim 9 in which the isothiouronium compound has the formula wherein R is a long chain, monovalent hydrophobic radical having from 8 to 25 carbon atoms, R and R individually are alkyl or hydroxyalkyl having from 1 to 4 carbon atoms, R and R individually are alkyl or hydroxyalkyl having from 1 to 4 carbon atoms or are combined in one divalent radical having 2 carbon atoms and Z' is a