how to polish cut rock surface
My son has me cut rocks in half for him with my masonry blade, but I canít polish the ends with any sand paper Iíve found, so whatís a good why to accomplish this task?
Buffing wheel and polishing compound after the finest grit. That would be my thinking. Use a dremel or maybe even a drill or better yet grinder. That's what I would try. Only ever tumbled rocks though.
You can cheat and use some carpeting (wool or cotton) and baking powder or some such fine powder. Couldn't hurt much (unless you melt synthetic carpet on, in which case you would have to remove the plastic).
I do some lapadary work down here and can assure you you won't get far with sand paper or buffing wheels as the rock a geode is made of is some tough stuff.
Most geodes are cut with a diamond saw for starters and then smoothed and polished on what's called a vibrating flat lap with silicone carbide grit and then polished with tin oxide.
Depending on how rough the surface is will predicate what size grit you start with 80 to 120 then 300, 400, 600, 1200 and then a polish.
Nowdays a lot of diamond grit is used as well but the process can take several days to do a nice job.
If you are bound and determined to get them polished find a rockshop or someone who does lapadary work and have them do it.