A labeling machine has a carrousel having a frame at the periphery of which a plurality of mandrels are rotatably mounted, and, at angularly spaced positions around the carrousel, object feeding means, label feeding means and object removing means. Each mandel receives a label strip from the label feeding means, winds it around the body of the mandrel so that a leading end and a trailing end of the label strip overlap. The leading and trailing ends of the label strip are sealed to form a sleeve label. The label strips are sealed by heat sealing means which include a pulse heating bar.