Abstract: A print head assembly for intermittently marking surfaces, such as packages and packaging materials, includes a heated ink supply means which engages with type elements as the latter move from a rest position, in which the type is heated, to a printing position, but which does not engage the type elements as the type elements move from the printing position to the rest position. The type preferably comprises rubber elements, heated in the rest position by a stationary heater. The ink supply preferably comprises an ink roll rotatably and freely mounted in an oven, wherein the ink roll remains in the oven throughout the whole operating cycle. Pneumatic cylinders are provided to move a type holder from the rest position to the printing position and vice versa, as well as for moving the ink supply means into and out of the path of the type holder.