The sliding system used with particulate rigid disks, involving a ceramic head sliding against a disk coated with iron oxide particles in a resin iv unusual in a number of ways. Perhaps the most striking is that, in use, there is for a long time no measurable wear, but once damage is initiated failure is rapid. To investigate this type of wear, numerous pin-on-disk sliding tests have been carried out. Analysis of the wear results suggests that in the authors' tests, the failure is caused by adhesive rather than abrasive or fatigue wear; however, it is not easy to judge whether failure is due to the wearing away of the alumina particles in the magnetic coating, or else to a polymer coating adhering to the pin surface.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference In Toronto, Ontario, Canada, October 8–10, 1990