If there is not sufficient lubricant, or if the lubricant has lost its lubricating properties, it is not possible for an oil film with sufficient carrying capacity to form. Metal to metal contact occurs between rolling elements and raceways. In its initial phase, the resultant wear has roughly the same effect as lapping. The peaks of the microscopic asperities, that remain after the production processes, are torn off and, at the same time, a certain rolling-out effect is obtained. This gives the surfaces concerned a varying degree of mirror-like finish. At this stage surface distress can also arise, see section Surface distress.
If the lubricant is completely used up, the temperature will rise rapidly. The hardened material then softens and the surfaces take on blue to brown hues. The temperature may even become so high as to cause the bearing to seize.