Do you have to flatten Japanese waterstones?

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lonestar1979

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Mar 2, 2014
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I have couple of cheap waterstones and they arent flat at all,but still i can manage to get a burr on them,and with sharpmakers triangle rod i take off the burr with flat side,and am getting pretty good edge.I usually use norton crystolon ,norton india or dmt to sharpen,just was trying waterstones luttlebit.Do you have to flatten waterstones after few uses?Whats the easiest way to do it without spending money?should i buy some more ex0ensive stones?Its deffinitely harder to sharpen on stones that arent flat,but i got nice convex edge after sone struggling to take the burr off.
 
You want them to be at least reasonably flat. Flattening can be done in a number of ways, and one of the cheaper and more effective methods is to buy a bit of loose coarse silicon carbide grit and a piece of float glass (a smooth glass "cutting board" is a good choice.) Dampen the surface of the glass and put a bit of the grit on there, and then rub the stone on it. The grit acts like ball bearings to concentrate pressure on the stone's high points, breaking the bond of the grains and wearing them down. Eventually you'll need to flip the glass over to get a flat surface again, and then replace it once both sides are dished, but it's quite inexpensive.
 
If you are sharpening tools with broad bevels you absolutely have to flatten them to get best results most of the time. You can move around on the stone to even out the wear, and this is a good idea anyway as a lot of concentrated work in one spot can knock some stones out of flat in a single use. This is good practice on any stone, don't blast it in one spot all the time.

I normally leave my stones a little dirty when I finish and put them back in a bath. When I take them back out I'll make a few passes with a diamond lapping plate to see where they clean up the most rapidly - these are the high spots and I'll sharpen on them mostly. If I'm doing a lot of sharpening I'll repeat this several times as part of cleaning the stone and just keep working the high spots. If it gets awkward to work the highest spots, I flatten the entire stone right down, but that normally takes only a little extra effort and time.

Over time I spread the wear around without having to do a lot of flattening and they wind up never out of flat by enough to effect my sharpening. In general it is a good idea to flatten them regularly one way or another.
 
Is there any difference in final edge when sharpened on high quality waterstones?or its just preference,that some people like diamond stones or oil stones with sil carbide and some just enjoy waterstones.
 
lonestar1979 said:
Is there any difference in final edge when sharpened on high quality waterstones?or its just preference,that some people like diamond stones or oil stones with sil carbide and some just enjoy waterstones.
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Waterstones tend to produce smaller burrs, the stone surface tends to stay more consistent.

Finishing grade waterstones tend to remove steel with less burnishing than comparable grit ceramics, plates, and other natural stones.

Due to the wide variety of bond strength, mud formation, abrasive type and density, some waterstones can be a real flop if matched with certain steels, but if well matched can produce really solid performing edges very quickly.
 
Heavy Handed,do you think theyre worth the price?How do they work on high carbide steels like s90v,s30v or d2?I dont take knives to high polish as i like toothy edges better,i i not have any Japanese styled knives with their steels,maybe they perform better when theyre taken to high polish as are high on rc scale .
 
That's a bit of a complicated set of questions to untangle. "Water stones" tend to be soft bond strength, which produces a slurry. A slurry makes final apexing with edge-leading strokes difficult, but has the advantage of giving uniform polishing and minimizing burr formation. The rapid shedding of grit also makes them very fast-cutting since you're constantly exposing fresh abrasive. This comes at the price of having to flatten them more often than harder stones. Most synthetic water stones are aluminum oxide, but some are silicon carbide. Either will sharpen steels with up to ~3-4% vanadium content without issue, but high-vanadium steels like S90V will give sub-par results when sharpened on them above ANSI ~400 grit or JIS ~700 grit (rough equivalents) and so are best sharpened on CBN or diamond in grits above that point. Most of those steels benefit from a toothier edge anyhow, though, so that's usually not a big deal. Steels mostly containing chromium carbides like D2 are no problem for water stones at any grit range.

In general a moderately firm coarse stone you can bear down on with hard pressure while shedding grit at a moderate rate is best for rapid bevel-setting. An intermediary stone relative to your intended finishing grit is best when soft and slurry-forming to prevent a burr from forming and polishing away scratches from the coarse stone. A hard fine stone is best for putting a crisp apex on the finished edge with edge-leading strokes using light pressure.
 
lonestar1979 said:
Heavy Handed,do you think theyre worth the price?How do they work on high carbide steels like s90v,s30v or d2?I dont take knives to high polish as i like toothy edges better,i i not have any Japanese styled knives with their steels,maybe they perform better when theyre taken to high polish as are high on rc scale .
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Overall they don't. Some folks claim good results but when working on higher Vanadium steels you can literally see how much less steel is coming off on the stone. S110v and 10v are more or less impervious to most finishing waterstones.

I have a handful of sets and they all work best at what they're good at. Some of my harder stones and my one finishing stone that is silicon carbide (Suehiro Rike G8) can work very well on D2, 440c, 154cm, but diamond plates work better on anything with 4% or more Vanadium, and even D2 is maybe better served by diamond plates.

I have stones that work great on cheap, gummy stainless, another set that excel on carbon steel at high RC - extremely good with woodworking tools. Most of them work well on low carbide content stainless such as any of the Sandvic series or other common pocket/belt knife steel.

If you like a working toothy edge on anything including high Vanadium steels, it is tough to beat a Crystalon stone.

They do make diamond grit waterstones that will eat high Vanadium steels, and I will be picking some up soon, but these are pretty expensive and not what one commonly means when talking about waterstones.
 
Thats what i thought,ill just stick to norton Crystolon stones,norton india and DMT.Thanx for reply guys.Only thing ill get is some diamond paste to load on strop to give knife few final passes.I do not have any Japanese knives,with their carbon steels high on rc.,and have too many knives to order new ones,maybe in future sometimes.
 
FortyTwoBlades said:
One thing I'll say is there's no such thing as too many stones once you get your bases covered. I use different stones for different tasks alllllll the time, and having more options at my disposal has only ever helped, never hurt.
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Thank your for validating my addiction position.


:p
 
Im sure some Japanese waterstones are excellent,but for my budget right now is too much,I have couple knives on order too LOL,and have too many already...100+...
 
Depending on your technique, you can make more effective use of smaller areas on a stone, but essentially you must have a flat surface. Murray Carter makes skillfull use of areas no longer than an inch due to his short scrubbing technique. If you prefer longer sweeping strokes, as seen with Jonathon Broida’s textbook Japanese style, you will need to flatten your entire stone virtually every use. This question is quite literally a matter of different strokes for different folks. Whatever you do, make sure you post pics of it here! :thumbsup:
 
I started using short scrubbing strokes to even out the stone,ill play with it for a while,im getting pretty nice convex edge on them,but still like dmt the best,then norton crystolon and india.Mostly use Opinels ,and few other knives like Mercator k55,and couple case knives,along with f.dick and swibo kitchen knives.I love the edge Norton india gives me on my carbon and stainless Opinels,also on kitchen knives.
 
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