weight parts by stirring the pigment in the acid for an effective period of time, from about 30 minutes to about 6 hours, and in an embodiment about 2 hours at a temperature of from about 0??? C. to about 75??? C., and preferably about 30??? C. to 50??? C. in air or under an inert atmosphere such as argon or nitrogen; adding the resulting mixture at a controlled rate to a stirred solvent, such as