Abstract: A highly-viscous material coating apparatus for use, e.g. in an automobile coating process, to coat a joint of a workpiece, may be mounted on a robot. It provides improved operation where the workpiece provides a reference surface parallel to the joint, where the workpiece provides a reference surface displaced from the joint at varying distances along the length of the joint, and where the workpiece provides no reference surface. Where a reference surface is available, an extendable spring-biased guide pin of the apparatus moves along the reference surface, and any positional errors are compensated-for by action of the spring. If the distance between the reference surface and the joint varies, the varying distance may be compensated for by various disclosed practices. The apparatus also can be used where no reference surface is provided by retracting the guide pin with respect to the nozzle and by controlling the robot so as to direct the nozzle to the joint.