In this video, I demonstrate the Nubatama Ume 180 Grit Waterstone. I do this doing a chip repair on a 330 mm long Tojiro gyuto. The knife has gotten a little dull as well and has a high grit finish initially. I find this large knife useful for initially breaking down larger portions of food, like one typically gets at a wholesale grocery store. It is a VG10 stainless steel knife.
I begin by soaking the stone. It is somewhat porous but saturates in a few minutes. It quickly removes the chip on the blade. To keep things even the entire blde length is redone to a uniform 180 grit edge. I demonstrate several styles of sharpening including doing the knife in sections, full sweeps, edge leading and trailing strokes and also using a 'W' pattern, wher a partial sweep is done, the knife is brought back up the stone and the sweep is continued.
The resultant edge is excellent for a 180 grit edge - toothy, easily cutting a paper towel. Not a great deal of mud is generated for a coarse stone. Another great Nubatama stone!