Method for applying a viscous material to a projecting rivet head of a component by means of an apparatus for applying a viscous material, wherein the apparatus is designed as an end effector for a manipulator, wherein the apparatus comprises a bell with a circumferential placement edge, and a feed line, wherein the material is able to be conveyed by way of a conveying means through the feed line into the bell, wherein the bell and the feed line form a nozzle body as a structural unit, wherein the nozzle body is connectable as an exchangeable module at an interface to a resiliently deflectable receptacle for length compensation, wherein the bell with the placement edge is able to be brought in a placing direction over a rivet head of a component in order to envelop the rivet head with the material, wherein a metering member is provided in the region of the bell or of the feed line, wherein, in the course of an application operation, a flow of the material is able to be influenced by means of the metering member, wherein the metering member comprises a movable metering piston, wherein the method comprises the following steps a. placing the bell onto the component, wherein the bell is put in a placing direction over the rivet head by means of a robot arm until the placement edge rests on the component; b. filling the bell with the viscous material, with the result that the rivet head is enveloped, wherein the metering piston is pushed forwards towards the bell by means of an actuator, as a result of which the bell is filled completely with material and the rivet head is enveloped completely with material; c. lifting the bell off from the rivet head, wherein the metering piston is subsequently moved back into a pulled-back position, while the bell moves laterally, in order to bring about separation of the material or material thread, wherein this pulling back of the metering piston also pulls material back out of the bell into the region of the feed line. a bell with a circumferential placement edge, and a feed line, wherein the material is able to be conveyed by way of a conveying means through the feed line into the bell, wherein the bell and the feed line form a nozzle body as a structural unit, wherein the nozzle body is connectable as an exchangeable module at an interface to a resiliently deflectable receptacle for length compensation, wherein the bell with the placement edge is able to be brought in a placing direction over a rivet head of a component in order to envelop the rivet head with the material, wherein a metering member is provided in the region of the bell or of the feed line, wherein, in the course of an application operation, a flow of the material is able to be influenced by means of the metering member, wherein the metering member comprises a movable metering piston, wherein the method comprises the following steps a. placing the bell onto the component, wherein the bell is put in a placing direction over the rivet head by means of a robot arm until the placement edge rests on the component; b. filling the bell with the viscous material, with the result that the rivet head is enveloped, wherein the metering piston is pushed forwards towards the bell by means of an actuator, as a result of which the bell is filled completely with material and the rivet head is enveloped completely with material; c. lifting the bell off from the rivet head, wherein the metering piston is subsequently moved back into a pulled-back position, while the bell moves laterally, in order to bring about separation of the material or material thread, wherein this pulling back of the metering piston also pulls material back out of the bell into the region of the feed line. a. placing the bell onto the component, wherein the bell is put in a placing direction over the rivet head by means of a robot arm until the placement edge rests on the component; b. filling the bell with the viscous material, with the result that the rivet head is enveloped, wherein the metering piston is pushed forwards towards the bell by means of an actuator, as a result of which the bell is filled completely with material and the rivet head is enveloped completely with material; c. lifting the bell off from the rivet head, wherein the metering piston is subsequently moved back into a pulled-back position, while the bell moves laterally, in order to bring about separation of the material or material thread, wherein this pulling back of the metering piston also pulls material back out of the bell into the region of the feed line.