polishing is necessary because at the end of fine grinding the mirror is covered with five micron deep pits and polishing with a pitch lap and a polishing compound smoothes away those pits.
Making a pitch lap is the next slide.
Polishing compounds: Cerium oxide is the fastest and most common polishing compound, I have conflicting reports as to whether Cerium is mildly radioactive or not. Red Rouge is three times slower so it is better for fine figuring.
The wooden cleats can not be substituted for carpet pads in the polishing stage due to the far greater forces involve
