Some years back I purchased a set of Preyda Arkansas stones for a friend but he never used them (or more accurately never had time for me to teach him to use them) so they sat in a box unused. I finally opened them and used them.

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For many reasons I really wanted to like this set of stones but I had trouble getting consistent results... And then I thought "is that corner low?" It turns out that two of the three stones are not flat. The finest stone, the "Black Hard" is out of flat on both sides. The stones are out of flat along both the length and the width, which means that it takes a lot of work for me to get results. The Soft stone is flat on one side, but not the other. The Hard stone is flat on both sides. If I had not figured this out years after purchase I would just take it back (WoodCraft has great support and a nice return policy). After a few years, it is on me for not checking.... But I have never checked a new stone for flat. On a whim, I went back and checked some of my other stones, which means that I checked about 35 stones. Every stone I could access (some are still shrink wrapped), was flat except for one heavily used Washita stone purchased off eBay. OK, many of my Washita stones were purchased off Ebay and I flattened the stone that was not flat. So all of my Norton, Best, and Dan's stones were all flat when purchased new.


Previously I have only checked used stones for flat. Two out of three stones out of flat. I do like the packaging and the form factor, something that is nice to keep at the office when I want to mindlessly do something while killing time.

I have only flattened Washita stones, never a Hard Black. I remember some advice related to Washita stones that recommended dressing the two primary sides with different grit Silicon Carbide crystals because the roughness affects the scratch patterns supposedly. I have never tested any of this, but i do have many different grits of Silicon Carbide crystals I can use. I expect that this would be rather pronounced with a "Hard Black" stone, which is pretty fine. Kind of a waste of time if I need to then polish the stone. I might do it just to do it, but how annoying.

I need to remove between 0.5 mm and 1 mm to flatten; closer to 1 mm.

I assume that most of you were smart enough to check your stones for flat.