On flattening water stones

[Ray Newman]

Colleagues: my water stones are getting worn & awhile ago I bought a ceramic "stone" to flatten the water stones.

However, I can not find the instructions!

Do you use it w/ a wet sharpening stone or a dry?

Or, do you soak the flattening stone??

This is the stone:
www.japanwoodworker.com/product.asp?s=JapanWoodworker&pf_id=01.090&dept_id=13122

[Tom Esh]

You don't have to soak the flattening stone, however it will be easier to keep un-clogged if both stones are wet. Better yet, use a bucket of water and do the flattening with both stones totally submerged. It helps to draw some pencil lines on the stone face to be flattened so you can see your progress. Be sure to thoroughly flush with with clean water when finished to remove any large grit particles. (An 8000 grit stone contaminated with a single 200 grit particle will make really ugly scratches on your nice mirror finish.:eek:)

[Michael Faurot]

Before you flatten your water stones, be sure to verify that your flattening stone itself is flat. I don't have experience with the stone you purchased, but I have used the Norton flattening stone. As it turns out, flattening stones can wear as well, and in turn need to be flattened.

When the flattening stone needs to be flattened, I've used a granite surface plate with 80 grit sand paper.

[Mike Henderson]

As Michael F. pointed out, using flattening stones is risky. When you rub two stones together, you get two conforming surfaces, not necessarily two flat surfaces. Since you wear your working stones in the middle, the flattening stone tends to become convex (because you get most of the contact around the outside of the flattening stone and less in the middle - so it becomes convex).

The more you use it, the more your stones tend to take that shape. Your working stones become concave when you rub them together with the flattening stone.

The best thing is to avoid the flattening stone completely and use something that's flat to flatten your working stones. Examples: A DMT diamond plate, sandpaper on glass or granite, or one of those expensive cast iron plates with abrasive powder.

I find the DMT diamond plate works best for me. I have the extra coarse/coarse one and have used it for years.

Mike

[Some people have the fallacious belief that you can flatten two water stones by rubbing them together. Anyone who has used a flattening stone knows that doesn't work. If it did, the flattening stone would be the flattest thing around - the more you used it, the flatter it would get. The fact that flattening stones have to be flattened on a regular basis is proof positive that rubbing two stones together only gives you two conforming surfaces, and those two conforming surfaces are essentially always one concave and one convex.]

[David Weaver]

Before you flatten your water stones, be sure to verify that your flattening stone itself is flat. I don't have experience with the stone you purchased, but I have used the Norton flattening stone. As it turns out, flattening stones can wear as well, and in turn need to be flattened.

When the flattening stone needs to be flattened, I've used a granite surface plate with 80 grit sand paper.

Just as a note of experience, my norton flattening stone was also out of flat when it was new - it was convex to a significant degree, and I didn't realize it until I was using sandpaper for something else and just flattened the stone I was using before I threw the paper out.

Check the flatness of the flattening stones first thing when you get them.

[Frank Drew]

I worked with Japanese carpenters at one time and their very effective method was to re-flatten their coarse stones on a normal concrete block with lots of water, and then use the coarse stone to dress the finish stone, again with water. I continue to use this method and it works well.