This is an interesting Podcast. It is 1:14 long.

I have used waterstones for sharpening for years. Up until a year or so ago, when I bought a Norton flattening stone, I used sandpaper on a glass plate for flattening every few sessions. Lately I have been seeing flaky results. I use a Veritas bevel guide, establish the main bevel with the 800 grit and then hone a microbevel with the 4000. The microbevel was not even or square across the main bevel, so I would compensate by putting a bit more pressure on one side of the chisel or iron. This works just fine, but a bit of a pain.

Anyhow, last night on a whim, I put a rule on the stones I had just flattened the day before. They were concave with about a millimeter dish in the middle! Not believing it, I grabbed a better straight edge and confirmed. A check of the Norton flattening stone told the tale - it was indeed convex, no doubt because of the use it had seen over the last year. It makes sense that it would abrade too, and the pattern makes sense, but it seems like it should not have happened this quick.

I have decided to abandon the Norton stone and go back to sand paper on a flat plate. The other option is to flatten the Norton stone, which actually seems redundant.

In any case, another reminder to always check your references

-G