A prong style file fastener and the method of manufacture is disclosed which has a protective element to prevent damage to paper documents and personal injury. In one embodiment, the prongs of the fastener are covered with a heat shrinkable sheath. In another, the prongs are overcoated with a powder coating which is melted thereon. A method of applying the sheath to the prongs uses a pair of jaws or V-shaped surface to drive the sheath onto the prongs.