Flattening the harder stones

J

jcmv4792

Joined
Mar 11, 2014
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How do you guys flatten harder stones like the norton india? I know these will stay flat for a long time, but I'd like to be prepared for when the time comes.

Do you use a regular diamond plate? I've heard of people using sandpaper for water stones but it seems like it would take a lot of sheets to flatten an india.
 
I have had best luck using a tile rubbing stone from Home Depot and some reel mower compound 120 grit silicon carbide. This has reliably lapped a whole bunch of stones for me, including my India stones. Works on either side, just work it longer on the fine side and it will break down into a finer and finer particle. I add a bit of dish soap to a small amount of water to make the paste. A coarse diamond stone might work as well, but I am a big believer in using a loose grit for this sort of work as it eliminates the possibility of glazing the stone. Sandblasting grit might work as well, but would be a bit slower I imagine. Some folks just use a flat concrete sidewalk and lots of water.
 
I would second Sic compound and a lapping plate as HeavyHanded has described. Of all the methods it is the most efficient.
 
ohh gotchya. Do you mean glazing the rubbing stone or the actual india sharpening stone?
 
I did my fine India with a coarse diamond and it glazed over. Took this off by rubbing on concrete with a lot of H2o and it seems better. I've not done the gray Home Depot stone. Mine was the Norton fine India with orangish, red color. DM
 
I use this on my harder stones and works fine.

894_zps1ee5954d.jpg
 
HwangJino said:
I use this on my harder stones and works fine.

894_zps1ee5954d.jpg
Click to expand...


It's a stone made specifically for flattening sharpening stones. Very common in all hardware and DIY shops in Asia.
I use a similar product... the only difference is a few more groves. I bought it in a hardware store in Osaka for about $8 USD.


Stitchawl
 
stitchawl said:
It's a stone made specifically for flattening sharpening stones. Very common in all hardware and DIY shops in Asia.
I use a similar product... the only difference is a few more groves. I bought it in a hardware store in Osaka for about $8 USD.


Stitchawl
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Can these be used on (have you used it on) stones as tough as an India stone or Arkansas, or is it just for waterstones?
 
HeavyHanded said:
Can these be used on (have you used it on) stones as tough as an India stone or Arkansas, or is it just for waterstones?
Click to expand...

I've never used it on an Arkansas oil stone. The last time I used an Arkansas stone was back in the early 70's, at which point I switched to the RazorEdge silicon carbide stones used dry for the next few years. After that I went to Japanese water stones. My flattening stone is quite rough, almost like a bubbled pumice stone texture but harder. I've seen similar looking stones being sold as cooking grill scrapers, but I don't know if those were made of the same material.

But living in Japan for almost 20 years, and watching the Master Sharpeners at work, and seeing the dished stones that they worked with, I've pretty much stopped worrying about flattening my stones all the time. When they get about 1/4" down in the center I begin to think about flattening. That's about what I would see them using on a daily basis. They would sharpen on a short section of the stone, wearing it down first in the middle, then on the ends, then finally flattening it when it started to look like a dragon's back! None that I ever saw were really concerned about having an absolutely flat stone.

EDIT: Here's a snapshot I took of one of the professional sharpeners working outdoors in my neighborhood in Japan... Note the condition of his stone. At this time he was doing his sharpening on the rear half of the stone, starting to wear that down to match the middle.

m9xu.jpg


Stitchawl
 
Last edited:
stitchawl said:
I've never used it on an Arkansas oil stone. The last time I used an Arkansas stone was back in the early 70's, at which point I switched to the RazorEdge silicon carbide stones used dry for the next few years. After that I went to Japanese water stones. My flattening stone is quite rough, almost like a bubbled pumice stone texture but harder. I've seen similar looking stones being sold as cooking grill scrapers, but I don't know if those were made of the same material.

But living in Japan for almost 20 years, and watching the Master Sharpeners at work, and seeing the dished stones that they worked with, I've pretty much stopped worrying about flattening my stones all the time. When they get about 1/4" down in the center I begin to think about flattening. That's about what I would see them using on a daily basis. They would sharpen on a short section of the stone, wearing it down first in the middle, then on the ends, then finally flattening it when it started to look like a dragon's back! None that I ever saw were really concerned about having an absolutely flat stone.

EDIT: Here's a snapshot I took of one of the professional sharpeners working outdoors in my neighborhood in Japan... Note the condition of his stone.

m9xu.jpg


Stitchawl
Click to expand...

Awesome picture. Is that stone made of the same material that commercial japanese waterstones are made of?(king, nubatama,suehiro...etc)
 
jcmv4792 said:
Awesome picture. Is that stone made of the same material that commercial japanese waterstones are made of?(king, nubatama,suehiro...etc)
Click to expand...


I shot this photo in Japan, 26km from Arashiyama in Kyoto prefecture. It can't get more Japanese than that! LOL!
When I asked him what kind of stone it was, and what grit, he just replied "It's a sharpening stone. Fine grit."
I guess it takes a gaijin (a foreigner like us) to worry about specifics. Perhaps it's more about technique than about tools.


Stitchawl
 
I think we obsess about a lot of items more than foreigners. (It's just a fine grit stone-- of some sort! ) Still, this dishing is common with water stones. I think he's some way learned to adjust his technique as his stone dishes so it still works. That's why I shy away from water stones as I still like my stones flat. A shocking good photo. But it sure brings to light a different mind set. DM
 
David Martin said:
I think we obsess about a lot of items more than foreigners. (It's just a fine grit stone-- of some sort! ) Still, this dishing is common with water stones. I think he's some way learned to adjust his technique as his stone dishes so it still works. That's why I shy away from water stones as I still like my stones flat. A shocking good photo. But it sure brings to light a different mind set. DM
Click to expand...

David, the point I was trying to make was that this sort of thing is the 'norm' that I see in Japan when I watch the professional sharpeners. The sword sharpeners tend to use the front end of their stones, causing them to curl downward from the middle to the ends, while the knife sharpeners get more of this middle dishing shape. For the most part, they just don't care about how flat their stones are until they get beyond what you see in the photo.

I don't remember who it was that made the post about a year ago, saying that he flattens his stones every few minutes while sharpening, and was looking for some sort of mechanically perfect straight edge to use for checking his stones. I just remember how I felt when I read that...

Because it's a hobby, many of us push things to absurd boundaries. Especially when just getting into the sport. I know I did, which is why I have a closet full of dozens of strops of different leathers, dozens of jars, bottles, and bars of different compounds, and 'almost' every sharpening system available...

...and why today I 'basically' use only two strops, one compound, and two sharpening systems.


Stitchawl
 
stitchawl said:
David, the point I was trying to make was that this sort of thing is the 'norm' that I see in Japan when I watch the professional sharpeners. The sword sharpeners tend to use the front end of their stones, causing them to curl downward from the middle to the ends, while the knife sharpeners get more of this middle dishing shape. For the most part, they just don't care about how flat their stones are until they get beyond what you see in the photo.

I don't remember who it was that made the post about a year ago, saying that he flattens his stones every few minutes while sharpening, and was looking for some sort of mechanically perfect straight edge to use for checking his stones. I just remember how I felt when I read that...

Because it's a hobby, many of us push things to absurd boundaries. Especially when just getting into the sport. I know I did, which is why I have a closet full of dozens of strops of different leathers, dozens of jars, bottles, and bars of different compounds, and 'almost' every sharpening system available...

...and why today I 'basically' use only two strops, one compound, and two sharpening systems.


Stitchawl
Click to expand...

I remember when you first posted that image - as I recall that was one of the neighborhood traveling sharpeners, pounds out a pile of kitchen cutlery per stop. Speculated at the time that if your stroke had an arc, and the stone had a matching arc, your edge is essentially flat. You described this gentleman as working the cutlery at a pretty high rate of speed and on a single stone. Once you get the hang of it, is probably a much faster and more natural method for most folks.
 
Yeah I've never used an Arkansas stone so I can't comment on that.

I've also been told by many old chefs (to flatten your stone with your knife). I keep my stones flat, but many Japanese chefs keep their stones sort of dished.
 
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