I've had some interesting results playing around for a few hours today with my Translucent Black Arkie. I tend to experiment a lot and teach myself things, always have, most likely always will. Anyway, using my little finish test piece (hardened steel, about 3/8" in diameter, flat on end where I check stone finishes) I tried a few different finishes and moved them all to the Ark last. Now one side of mine I lapped at 120 grit and leave it there, the other is a near mirror. I also relapped the finer side today, and tried a new finishing method - SG20k lapping! Worked pretty well actually.
I lapped on silicon carbide first up to 1500, then flattened the SG20k with an Atoma 140. Left the slurry from flattening on the stone and then used it to basically loose grit lap the Arkie with SG20k grit particles. I reflattened/refreshed the slurry on the SG20k about 5 times and spent over an hour on just this final operation. Here's how she looks now (these are both completely dry stone pics - no liquid or oil on the surface):
http://i240.photobucket.com/albums/f...914_013053.jpg
http://i240.photobucket.com/albums/f...914_014516.jpg
Anyway, went through a whole lot of different lubricants and liquids, tried water, synthetic ATF, water with dish soap, Tap Magic cutting oil, mineral spirits, even lighter fluid. Some make the stone cut coarser and some finer, but I had never been able to get much beyond a hazy mirror finish.
Until today, when I found it. Using the Tap Magic, I applied 3 drops to the stone, then wiped it all back off with paper towel as dry as I could. Starting from a 1500 grit Suehiro synthetic waterstone as my baseline finish, I honed the test piece on the coarser side of the Ark until all the Suehiro scratch marks were gone. After that, I flipped the stone to the fine side and used the same process with the cutting oil as I had on the coarser side.
Lo and behold - a bright shiny mirror began to emerge! There's a trick to keeping it though - after every 30 strokes or so, wipe off the swarf (which amounts to a very barely light gray haze on a white paper towel) and add 3 more drops of Tap Magic and wipe it off. The surface just continued to get better and shinier/brighter the more I did it. If you just keep honing and don't do this step, the finish starts to cloud and goes back to the hazy mirror.
I think using the right method this stone might well be able to give the SG20k a run for its money. I will take some pics of the SG20k finish vs. the Trans Black Arkie and add them shortly.