Suitable polyamines are those having the formula R1 R2 --N((CH3)x N)n --R1 R2 wherein R1 and R2 are independently a hydrogen atom or a C1 -C22 straight or branched chain aliphatic, hydroxyalkyl, amidoalkyl, carboxyalkyl, cyclic, alkoxy, polyalkoxy or hydroxypolyalkoxy group, x is an integer of 1 to 3, and n is an integer from 1 to 5.