and why not to use them!!!!!

For the occasional glass pusher, polishing pads are to be avoided. I know it sounds like a great time and labor saver, but!!!!! If you use the pads, do not put then directly on the grinding tool. The reason for this is that the pads have thickness and applied to the tool directly, they will change the radius of curvature (ROC) so that the polishing tool will not accurately conform to the mirror. When using pads, put a layer of pitch on the tool and then put the pads on the pitch. This will allow the tool to be at the same ROC after pressing. No amout of pressin will do the job if the pads are just applied to the bare tool. Pads will also not give you the quality of polish that a pitch lap produces. If you polish with pads, you will still have to make a new pitch lap to complete the polish and figure of your mirror. The time saved by using the pads is lost if you consider the making of a new lap and cleaning up the surface before figuring. Pads are fine for production of mass produced medium quality spherical optics but should be avoided by the serious ATM.

Jarvis Krumbein