Logitech's unique lapping and polishing process enables you to achieve highly accurate results. Undercut is the amount of material which will be removed from the sample after the stop ring has made contact with the lapping plate, provided the lapping operation is allowed to continue beyond that point.

The amount of undercut is governed by the grain size of the lapping abrasive and maximum undercut will be reached after further processing; the duration of this extra processing time is dependant on the material.

In effect, it allows the specimen to continue being lapped or polished after the material has lost contact with the polishing plate. Depending on the grit size of the abrasives, used, particles continue to flow between the plate and the material, gently removing very small amounts of surface material. This process is perfect where the material is fragile or brittle.