Can you polish with Silicon Carbide: YES

Here is the water tumbled candy rhyolite.

Here's some of the other rocks I pulled out that I didn't get a chance to edit/post last night:



To my eyes, the sheen on these is as follows: 

the Labradorites are satin to semi-gloss,

the two larger Petosky's are satin, the smaller one is eggshell 

the black speckled stone is semi-gloss 

Again, this is after tumbling in 1500 grit SiC

So, this result was achieved through wet sanding with diamond sharpening stones up to 1500 grit, then switching to wet sanding with silicon carbide sandpaper with: 3,000, 5,000, 7,000, and 10,000 grit papers.  No polishing or burnishing of the stone.




NOTE: I flipped the image in photoshop to see that I could easily read the quarter from the reflection off the sanded stone.

So... this is kind of a set-back.... but also not really....

Meaning, this didn't turn out to be the apples to apples comparison that I hoped it would be, instead it's more of an apples to oranges comparison  

My polishing media for both was supposed to be the fine grained corncob media that came with my Eastwood tumbler + 2oz of 12,000 grit AO in the first bowl, and 2oz of 1 micron SiC in the second.   I put what I though was about half the bag of corncob in with the 12,000 grit AO polish, but that actually ended up being closer to 75%.  So the 1 micron SiC didn't have nearly enough corncob in the bowl for good movement, so I ended up putting 2x the ceramic balls in the bowl to get the movement right.     I should have started by weighing everything out to get things as close to equal as possible   



The three Petosky's on the right are from the 12,000 AO, the two on the left are from the 1 micron SiC, the other two were stopped at 500 SiC. Although the AO & SiC look nearly the same here, in person the AO stones are definitely shinier.


This photo gives a better representation of what I'm seeing, the right stone run through 12,000 AO, the left the 1 micron SiC.  Honestly, the 1,500 SiC result was better than the 1 micron SiC result....

So I gave up, and switched to a wet process, & I'm doing the entire process over, started with 220 grit yesterday morning & will run it till Saturday, I'll then switch to 500 SiC, then 1,500 SiC, before splitting the load in half & finishing half with 12,000 AO & other half with 1 micron SiC - doing 3 days for all stages.  

This time I'll remember to weigh out the rocks and filler to get both halves as close to exact as possible for the final polish!

Also found a method of keeping the rocks wet without continually adding water!  I have some 3/4" thick closed cell EVA foam that I cut to fit inside the Eastwood lid, which fits just right over the Lyman plastic bowl.   Being plastic, it's impervious to water.... and being closed cell foam, the EVA does not absorb water, and with the addition of some soft rubber spacers sealing up the bowl completely, it keeps all the moisture trapped inside the bowl!!! 

 I spent about an hour Wed morning making sure I had the right amount of water in the mix.  I checked progress at lunch today, & it did not need water, I checked again after work, and all is still good, that's about 36 hours without adding water!!!

I suspect too much water in contact with a healthy amount of soap. Not necessarily a bad mixture. IMHO