How high a grit one should one use when sharpening? Some people sharpen with a 1000/8000 water stone. There are 12000 and even higher grit stones out there – though I have learned that the grit rating scheme is not always consistent, so that a 12000 is not necessarily finer than a true 8000, for example.
In the class I took this weekend, the grits were: 220 400 1000 2500. For a chisel whose back was not flat, and 220 was taking too long, the teacher suggested 120 or 150. And for damaged chisels (one with a chip in the cutting edge), I used a 36-grit wheel on a 1200 rpm grinder. The latter, when taken through the paces, yielded a beautiful looking, but more importantly, SHARP chisel.
A reason for going to 2500 or higher is the satisfaction of the nice mirror finish, but I’m not convinced that it makes a huge difference in cutting wood, and I doubt it makes the edge last longer.
Before taking the class, I occasionally used a cheap combo stone that I bought at a Chinese restaurant supply, really intended for kitchen knives. The two grits are probably in the range of 200/400, and I have always used it dry. It does not provide a mirror finish or anything close, but it did greatly improve the usability of my chisel, without going to higher grades. And I sharpened only the bevel side, because I didn’t know better.
Now that I know better, I am certain I will get a better edge, but it will be at the cost of some additional effort. With sharpening, there is this law of diminishing returns, where additional effort does not give that much improvement. For me, I am looking for the sweet spot between not too much effort and yet sharp enough for my purposes. But it isn’t much extra effort to go to a higher grit or two than necessary, and it looks sweet when you do that, even if the additional sharpness is mostly theoretical after the first use.
-- Mark, hack amateur woodworker, Medford (greater Boston) MA