Hall's Pro Edge, Arkansas Stones Arkansas Sharpening Stones Natural Native Stones
, has the best surgical black Arkansas stones I've ever used or seen. They're as good as Norton transluscents. Hall and Norton transluscent stones are both also very good -- but too pricey for what they are. Norton blacks are extremely expensive and pretty much unavailable. I wouldn't bother with Dan's or any other brand.
A finishing stone like a surgical black or transluscent is quite dense, doesn't load up easily, easy to clean, and only requires flattening a couple of times a lifetime if that much.
However, considering the price a good Arkansas stone costs, if you're in it, you're in it partly for the nostalgia, partly for the hobbyism, and partly because you really hate flattening. That is, none of these stones polish as quickly nor as well as a Shapton Pro 5000# and certainly not as well as an Arashyama/Takenoko waterstone. From a pure performance or performance/value standpoint, I'd go with the Arashyama/Takenoko (same stone under either name, even though the Takenoko is listed as being a finer grit) stone over any Ark.
If you're finest stone to date is something like a fine India (the red surface on a Norton combination stone) you'd serve yourself well by buying an intermediate stone at the same time you buy the black. I suggest a soft Arkansas, also from Hall's.
With Arkansas stones: Don't buy "combination" stones. They are held together with glue and can eventually separate. When you buy an Ark, you're buying for the long term.. Do buy at least 3/4" thick. If you're buying an 8 x 2 x 1 (or 3/4) spend the money on a Norton "sharpening station." If you have the space for it, buy a 10" or 11" long stone, they make sharpening go faster, as does a 3" wide stone.
I run my soft Arkansas through the dishwasher after every multiple-knife sharpening session. I clean it with water, scouring powder and a brass (barbecue) brush when it starts looking really dirty -- after three or four sharpening sessions. I never scour the black, but run it through the dishwasher at the same time I do the soft because it's convenient. You could get away with cleaning it less frequently.
My experience is that even the best modern soft Arkansas is going to take some time to "open up." That is, they'll all be frustratingly slow the first few times you use them. But once you wear the lap off the stone, they're OK -- if not as good as the stones sold twenty five years ago.
The actual abrasive material in any Arkansas stone is a chert mineral called novaculite. The difference between grades is in the amount of novaculite and the density of the sedimentary matrix holding it. The reason I recommend Hall's is that the quality of Arkansas stones varies depending on the quarry and vein from which they were taken. Hall's leases a deposit on federal land which is not nearly as picked through as Norton's St. Gobain quarry, Dan's or the other major producer whose name escapes me (it doesn't sell under it's own name, but is responsible for the best "house" brands sold by woodworking, razor and music stores).
I also recommend Hall's for customer service.
That said, Norton makes wonderful sharpening materials generally, and excellent Arkansas stones in particular. Dan's are very good stones, too, as are the good house brands.
Any more questions? Just ask.