Flattening stones

[Osvaldo Cristo]

https://youtu.be/bsbziMxL2Ss

It looks a good instruction video, but I cannot understand why he is using the abrasive powder. I would think the abrasive grint from the stones would be enough...

Anyway, I expect the video can be useful for you.

[Rafael Herrera]

Use of silicon carbide grit as an abrasive to flatten stones has been mentioned before. It's a very fast, dustless and cheap method, yet flattening stones, diamond stones, sandpaper, cinder blocks, etc. are often put forward.

[Luke Dupont]

Arkansas stones are extremely hard and not very abrasive / gritty, so flattening them against eachother without abrasive powder would take ages.

[Warren Mickley]

I watched the video. I think the guy is long on theory, short on experience. My black hard Arkansas stone is 1.000 inches thick, the same as it was in 1975. A soft Arkansas stone wears slowly; I think I have flattened it twice with SiC on glass in the last forty years. The elaborate procedures are not necessary for high quality sharpening.

As Luke suggests, Arkansas stones are more polishers than abraders; they are good at polishing an already sharp edge, not so good at removing material. Historically, oil stones like this were used in conjunction with a water stone which did the rough work. Abrading an Arkansas stone leaves the stone scratched which temporarily increases its cutting ability, but decreases its ability to polish an edge.

[Rafael Herrera]

I've used SiC grit to flatten dished vintage stones, which I accomplish with coarse grit, 90x. I can't see the point of polishing the stones, they'll eventually settle down with use. Washitas wear a little faster than soft Arkansas, since some are less dense than soft Arkansas. The one that I use the most has worn a bit.

[Luke Dupont]

I watched the video. I think the guy is long on theory, short on experience. My black hard Arkansas stone is 1.000 inches thick, the same as it was in 1975. A soft Arkansas stone wears slowly; I think I have flattened it twice with SiC on glass in the last forty years. The elaborate procedures are not necessary for high quality sharpening.

As Luke suggests, Arkansas stones are more polishers than abraders; they are good at polishing an already sharp edge, not so good at removing material. Historically, oil stones like this were used in conjunction with a water stone which did the rough work. Abrading an Arkansas stone leaves the stone scratched which temporarily increases its cutting ability, but decreases its ability to polish an edge.


All true!

The one thing I will mention is that for whatever reason, sharpening knives a lot on my Arkansas stones will bring the Washitas and even the Softs out of flat surprisingly quickly. In just 4-5 years that I've owned some Softs from Dan's, I've had them get out of flat twice already from sharpening knives and the like regularly.

Sharpening woodworking tools however, they remain flat for many years indeed.