Originally Posted by
Tom M King
The Sigma 400 is a fast stone, and the 1,000 takes its scratches out as easy as any other step between stones. I wish I had bought it years ago. The only "stone" I have that's coarser is a diamond plate x-coarse, but it rarely gets used. If the 400 is not enough, it goes to the CBN wheel. The 400 really speeds things up when 1,000 is not quite enough for flattening the back of a chisel or plane iron. For flattening the finer stones I have one of the Atoma 400 replacement sheets on one half of a 9x12 granite surface plate that stays in one sink. There is another 200 sheet on its way for the other half for coarser stones. I probably would have ordered 140 if I had seen Patrick's post before I put in that order.