Particularly suitable carboxylic acids include amido-containing carboxylic acids such as those represented by the general formula ##STR3## wherein R is a hydrocarbon or substituted hydrocarbon group having from 1 to about 29, preferably from about 2 to about 17, carbon atoms; R' is hydrogen, an alkyl or hydroxyl substituted alkyl group having from 1 to about 3 carbon atoms and R is a divalent hyd