A packing machine for wrapping compressed insulation products in heat sealable plastic film, including a forming tube having product feed means to move or hold the product within it, a former to reconfigure a web of heat sealable plastic film into a longitudinally open tube around the forming tube, a heat welder to close the longitudinal opening and provide a continuous plastic tube, take-off conveyors which receive the plastic tube containing the product at a point downstream of the forming tube and displace the product a preset distance from the forming tube to create a pocket, means to close the plastic tube behind the displaced product and ahead of the next product which is fed into the forming tube as the product is displaced, and means to cut the plastic tube between the two closures so formed, characterised in that air is removed from the pocket before closure by applying vacuum, thereby reducing the time for closing the plastic tube. The invention also encompasses a method of using the packing machine.