Hardness is a big issue for me. There are some rocks that I have abandoned due to simply being to hard to work with easily, and my hones are generally fairly hard for hones. I have a piece of rubber that goes down in the sink then my DMT lapping plate and then water to cover and a lot of elbow grease. I think If it wasn't for the work of lapping I would be able to turn out hones with a great deal less labour. I am going to guess that lapping and finishing is at least half of the effort of making hones. It is also where some get culled because it is simply too much effort for a variety of reasons. I have not yet figured out how to cut a warped hone flat. Once they get there I give it one shot to make it straight on the saw and if it doesn't work I chuck it. Sad but true. Sometimes correct that takes forever. You may be having to take and 1/8 or 3/16 off of most off the hone. On a very hard hone that is a lot of lapping.