Abstract: An ultrasonic transducer assembly for hygienic ultrasonic sealing is disclosed. The assembly includes a hygienic ultrasonic sealing area and a non-hygienic area, separated by a barrier wall. The barrier wall has an opening which allows an ultrasonic converter to move back and forth ("reciprocate") through the opening. The ultrasonic converter is also vibrated at an ultrasonic frequency by machinery located in the non-hygienic area of the machine, and transmits those vibrations to the hygienic area of the machine. The converter has a null area at which the converter is vibrated substantially minimally and other areas which are much more vigorously vibrated. A generally cylindrical sealing surface is fixed with respect to the null area of the transducer. The sealing surface is wiped by a wiping seal mounted to the edge of the opening. These two parts may also be reversed.