Abstract: An oven for heating tubular parisons has a conveyor passing therethrough with parison holders rotatably mounted thereon for vertically supporting the parisons. To assure uniform heating of the parisons around their circumferences, the parison holders are rotated about their axes. For this purpose teeth projecting out from the parison holders engage a group of stiff brush-like bristles, arranged either as tufts or as a continuous stand thereof, fixedly arranged alongside the conveyor path at a distance therefrom to be engaged by the said teeth.