Failed Sigma Power 10K Stone

[JoethePro]

Bummer! I'm actually not sure what killed it, but I noticed a crack in the stone when I was flattening, and it just came apart. I dried it out and saw cracks all over - and they aren't just surface cracks - if you look closely at the photo you can see some of them.

I did let it perma-soak for a few weeks like I do my norton stones, so I guess that could be it. It's too bad also, I was really liking how this stone cut!

[Mike Brady]

That's a bummer. Since you mentioned the perma-soak, my gut feeling is that practice can't be good for any stone. Some perhaps can tolerate it, but why do it as an ongoing practice? You probably like having stones at-the-ready for spontaneous honing. What I do is have honing sessions where I will do maybe six blades or more that have accumulated. I have a spare blade for a few planes that I can switch in between honing sessions. I also keep a strop handy to freshen a dulling chisel just a bit.

I learned my soaking lesson on a Chosera stone I had. It got multiple surface cracks but never fractured. It too was a great stone. Now I never soak for more than a few minutes.

[HomerLee]

Yikes! Guess I better get me Stones out of that Veritas Stone Pond. Never thought of this.

[Fisherman]

Mine stay in water all the time, it must depend on the material.

[AHill]

JoethePro said:

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I did let it perma-soak for a few weeks like I do my norton stones, so I guess that could be it.

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I believe this is the cause. Sigma Power Select stones break down faster than some of the other stones. I suspect the binder in the stones got pretty soft by soaking that long. Only other thing I can think of is if the water froze at one point. Lots of little cracks to me indicate a binder softening. Even Stu (Schtoo) who sells them via Tools From Japan, recommends only a 1-2 minute soak on the lower grit stones - "The stone should be damp, but not wet for the best performance."

[JoethePro]

It's possible that the problem was that it was in an open container, and the water evaporated off enough to expose the stones side. That let water wick through them and maybe the uneven moisture did it?

I know my Norton's never seemed to mind, but then again I don't like their cutting action, and I'm sure it has to do with the binder vs stinter construction.

[Gregory of Sherwood Forest]

My Sigma PS II have resided in my LV water pond since I bought them a couple years ago. No issues and they are used by every one I teach sharpening to.

[JustinTyson]

I bet you'll be able to repair that with superglue. I had a 4000-grit stone suffer the same fate after 8 years of use, but I was able to repair it with superglue and it's still going strong!