As I talked about before I invested in some Spyderco sharpening stones after reading Derek Cohen talk about them on this blog. To be perfectly honest, the idea of having something that doesn’t need to be replaced is top of mind for me. I don’t like buying disposable things (although I might have changed my mind on that. More on that later…) so after hearing folks talk about these as one and done kind of stones I was intrigued. What I find funny though is that the manufacturer says that these stones are flat out of the box. While I believe this is true – I think its true within reasonable tolerances. There seems to be two camps when you talk about Spyderco stones. The ones that say “It’s flat and if it isn’t ship it back” and the other that says “It needs to be flattened”. While my stones seemed reasonably flat I was certain they weren’t 100% flat. Despite this, I resisted the urge to flatten them. Many folks who attempted the process said it was long, boring, and had a good chance of destroying any stone you used to flatten them. I kept telling myself that they were flat enough but after continuing to struggle with sharpening my low angle jack plane I finally decided to just do it.

I only have a single 1000/300 reversible diamond stone and while I’ve had it for a few years I wasn’t anxious to destroy it as part of this process. I read a lot of advice and folks seemed to suggest flattening them under running water to keep washing away any swarf. So while my wife wasn’t looking I put the stone (in the holder) in the kitchen sink, and started at the ultrafine stone with the 300 grit side…

You can see above that Im starting to remove material from the lower left and upper right corner. I kept at it for another 10 minutes and started to see some more reasonable progress…

It would appear that the plate is slightly convex. Another 20 minutes or so and I was looking even better…

I tried as much as possible to flip the stone to make sure I wasn’t pushing too hard on my heel etc. I started developing a pattern where I would lap the plate for awhile in the sink covered with water, then take them out and do it for a bit on the counter, then once I saw swarf forming from the lapping I’d rinse them off, flip the plate, and do it in the sink again. I didn’t get a final picture of this plate, but here it is almost done…

Next I moved onto the medium stone. Same process – but this one wasn’t obvious where it was still high or low so I marked the surface with a Sharpie…

This one seemed to take longer, perhaps I was just getting tired of the process…

Almost done….

And once again I failed to get a final picture but I did manage to get all the marks to come off. Once I got them both flat on the 300 side I hit both with the 1000 side of the diamond stone. Same process – In the sink, on the counter, rinse off etc. I did that twice for each stone.

So now I was wondering if flattening actually made a difference. So I sharpened two chisels. One using the side I had just flattened and one using the untouched reverse side of the stones (assuming they were still out of flat). The results were interesting. I bought a cheap pocket microscope on Amazon so I could take a closer look at the blades. This is what the blade sharpened with the newly flattened Spydercos looked like…

Im not an expert at this – but it looks fairly sharp and the edge looks straight. Now I took a look at the blade sharpened on the unflattened side…

Again – the edge looks pretty good. But notice the flat surface – the level of polish is 100% different on each blade. So then for the real test I went to a block of hard maple…

The cuts on the right were made with the chisels sharpened on the flat sides. The left the other chisel. The picture makes it hard to tell – but the right side has a much smoother surface then the left. Pushing the chisel on the right was also much easier. I realize this is all subjective – there are lots of variables here which could have a big influence so I wouldn’t take this as a totally valid test. BUT I do think in my case that flattening the stones has made a difference for me.

A bonus? My diamond stone seems to not have been impacted by the lapping! I think the key is to keep rinsing off the swarf or just do it under water so the swarf clears.