This chemical reaction roughens the surface of the coating. The result is lower clip levels, lower 2F TAA, higher overwrite, higher peak shift, and higher torque. The initial clip level cannot predict this deterioration. Accelerated aging at temperature and humidity extremes is normally used by the diskette manufacturer to control this quality issue. Internal stresses are present in media.
Improper processing can generate poor substrate or hubbing quality and warped media.
Special substrate treatments are required both before coating and after the cookie is punched. Some coaters eliminate these steps in response to cost pressures. Although disk warping can be relieved over time, it can also worsen. Initial clip level is not relevant. Only careful visual inspection and modulation tests can identify such problems in advance.