According to some aspects, a de-powdering subsystem for an additive fabrication system is described. The de-powdering subsystem may comprise a bath subsystem. The bath subsystem may comprise a reservoir configured to contain a liquid and to accept objects to be de-powdered into the liquid, and an agitation facility configured to cause currents within the liquid. The agitator facility may be at least one of (i) a pump configured to circulate the liquid within the reservoir, (ii) a heating element configured to generate convection currents in the liquid, and (iii) a stirrer driven through a linkage to a motor. The bath subsystem may comprise at least one ultrasonic transducer configured to apply ultrasonic vibrations to the liquid within the reservoir.