Cold Polishing

[lucho/lachezar/]

Good advice by Lucho...I find cold-working with a hand held machine is very challenging, precisely because of the variations in pressure and angle, dwell time, etc. The first challenge is to get the surface totally flat. Ronny, I disagree here - the only surface that must be flat is the bottom of the peace and there are very few reasons for polishing that one... On the contrary, making all other surfaces slightly protuberant (especially working on a flat grinder) gives you the opportunity to work with a smaller surface at a time and thus fighting with a lot smaller friction and holding your piece with much better control of pressure and movement. Same for cerium polishing - instead of pressing with shaking hands a large surface to the disk it is a lot easier if you move the piece a bit like a roller and simultaneously across the disk. I usually put a hose dripping at the edge of the disk like one drop per second and move the piece from center to edge keeping it this way from preheating. Similar with the hand-held polisher - I turn on the water slightly - it is invisible for the eye but if you bring the handle close to cheek you can feel the tiny water drops. Then put some cerium on the surface to be polished and move the disk slowly back and forth, never holding it at a place and following a straight line rather than circular (this applies for grinding against swirls).And I believe that cerium polishing is much more risky to the glass than with a flat lap-type machine, because although there is heat generated by the friction on both machines, when the entire piece is on the pad, the heat is uniform across the entire surface, whereby with a hand held, the surface area under the disc heats up, while the adjacent area is stone cold with water...so attention to movement is critical.
As far as swirl marks, I like the smoothing pads by His very much, because they are not oriented diamonds, and are available as coarse as 100 grit, although these things have a somewhat different scale...as an example, I use the 325 smoothing pad after the 400 nickel-plated disc. http://www.hisglassworks.com/cart/cart. ... tail&p=480
Hope this is the kind of info you're looking for.

Lucho

[RonnyR]

Not sure if I'm following you here, Lucho...those that do, as an example, geometric optical sculpture, say of a pyramid, would need to polish all five sides, and all those sides would first need to be flat to do that...are you saying that you use a wet polisher to conform to irregular surfaces? I tried that once and got very wet...