While SiC abrasive paper can be used for grinding, resin-bonded diamond discs such as MD-Piano provide excellent flatness and long life. Napless cloths are used for diamond polishing while low-nap clothes are used to polish with alumina or colloidal
silica abrasives. In most cases, a reticule is used to make the measurement. Alternatively, many image-capture software
programs allow operators to make point-to-point distance measurements.However, these systems must be properly
calibrated.