Dissolve Borax in 1/2 cup cold water; set aside. Dissolve lye in 1 cup cold water. It will be lukewarm when it is dissolved. Stir lye solution into melted grease, stirring constantly until blended. Add Borax solution and ammonia; stir until thick as honey. Pour into flat large enameled pan. Let stand 5 hours before cutting into bars or long strips. The finished produce will be very white soap. Can be cut into thin strips, put through a food grinder to make soap powder for washers.