Opal polishing

[Grant]

Can someone please give me an idea as to what speed I should run a polisher at to polish opal

[Aussie Sapphire]

There will be others here much more expert who can give you more specific advice but with opal you would want to be careful not to overheat the stone.  So dont go too crazy with speed.

What is your current method?  Polish type?  What type of polishing pad?  Machinery you are using?

cheers
Leah

[Robol]

Hi Grant.
 I am not an expert, but for what it is worth; I use a triple 200mm. diam. vertical disc set up with 5mm. neoprene backing to each disc. The first disc has a 600 mesh miracle-lap glued to the neoprene. The second disc has a 1200 mesh lap. The third disc has a leather face glued to the neoprene and I use cerium oxide on this. The discs turn at approx. 580 rpm. The discs are cooled by using small sprinkler outlets fed to the centre of each disc which is then dispersed across the face of the disc as it rotates.

[Rusted]

I agree about Cerium, great stuff for Opal and any of the softer glassy stones, I use it on felt at about 200 RPM. Not too wet but not dry either, paint a slurry on the wheel then as it dries just a squirt from a spray bottle to keep it damp.