A mind needs books as a sword needs a whetstone, if it is to keep its edge.
George R.R. Martin
Now that we are geared-up and our sharpening stones are flat, let’s make our blade sharp. The first step in sharpening a new blade is truing the ura. So let’s get to it.
General
All standard chisel blades and plane blades, whether Japanese or Western, need to have a planar flat or ura that it will be in contact with the sharpening stones its full width, and ideally, full length. Perfection is not necessary, however, so don’t let yourself get obsessive. If the ura is arched (concave), for instance, so it is in contact with a flat sharpening stone near the neck of a chisel, or head of a plane blade, and the cutting edge, that may be workable, but it must be in complete contact right behind the cutting edge. I cannot stress this importance of this point too strongly.
Once the ura of your chisel is flat and true, you should not need to true it again unless the blade needs major repairs. Japanese plane blades, on the other hand, are a little more complicated because repeated sharpenings tend to gradually wear out the land right in front of the cutting edge, called the “ito ura,” and the bevel must be tapped-out to compensate, and the ura re-flattened. I won’t delve into the subject of “tapping out” the ura of plane blades in this post but will save it for future discussions about Japanese planes.
Evaluate the Ura
The first step in flattening or truing an ura is to evaluate its condition. Don’t start grinding away willy nilly without first checking it and making a plan. If you find you cannot stop yourself, don’t walk but run to the nearest pharmacy and buy a bucket of the medicine discussed in part 19 in this series about maintaining sharpening stones.
There are several ways to check the ura’s condition. A narrow straightedge works well in most cases. Place the edge on top of the full length of the shiny land at one side of the ura all the way to the cutting edge. Keep the straightedge touching the land; Don’t let it span the hollow- ground urasuki. Hold the straightedge and blade up to a strong light source and look for light passing between them. This technique is quick and dirty and will suffice in most cases, but does not tell you a lot about twist.


Another method to check the ura for planar is to paint the shiny lands with dark marking pen ink or Dykem liquid, apply a bit of fine sharpening stone mud to a piece of flat glass, like the piece mentioned in Part 17, and rub the blade’s flat or ura over the glass. The high spots will become obvious. If the ura is banana shaped (convex), mark the high spot with your marking pen. More often than not, the ura of chisels will be generally flat, but the last 6mm or so of the cutting edge will be curved upwards towards the chisel’s face.
I learned two things from my examination of this Sukemaru brand atsunomi. First, there is a high spot (convex) at the skinny land on one side located approximately 1/2 to 5/8 the blades’s distance from the cutting edge. The land on the other side seems a little low. Hmm, curious. This is a bit unusual, but it happens when a blade warps during heat treat, which Shirogami steels tends to do frequently.
The second problem I observed was that the last 3~4mm of the land right behind the cutting edge curves downward away from the ura just a tiny bit, enough to cause problems.
I next need a plan to resolve these problems with a minimum of time and effort and without making things worse.
Make a Plan
The temptation to start grinding away immediately will be powerful. If it becomes too much, take a coffee cup or three of the medicine mentioned above and slather it on your head forcefully. Don’t hold back, for Pete’s sake, rub it in really good now. Some say my excessive use of this medicine is why I am as bald as an egg, but I prefer to believe it is caused by the light radiating from my gigantic brain (ツ). Thank goodness for my aluminum foil skull cap with its protruding copper wires!
Any plan needs goals and objectives. In this case the goal is a perfectly planar ura, but if this goal is difficult to achieve quickly there is an objective you should plan to achieve immediately in any case, one that may make it possible to achieve the larger goal over multiple routine sharpening sessions without any special effort.
As I keep harping, to make a chisel or plane work well, you need a flat area right at the cutting edge. This is where the cutting occurs and the area I need to keep sharp, so I will make creating this flat area the first objective in my plan, and then determine the steps to achieve it. Make certain every step in your plan and every stroke on the stones gets you closer to this objective, not further away. This means working smart.
If the blade is arched (concave), touching at two points, one near the neck of the chisel blade, or head of the plane blade, and at the other at the cutting edge, and not in between, all is well. I recommend you leave a blade like this as-is because after a few sharpening sessions the ura will become flat and twist-free without any special effort, and the blade will become very sharp and be entirely functional.
If the blade is wavy (rare) or banana-shaped (convex), your plan needs to take those details into account.
I located the highest point of the bulging area at the ura and marked a line across it with my marking pen. I then measured halfway between this line and the cutting edge and made another line. This area we will call the “focus line.” It is here where I need to focus the most pressure when grinding down the ura, not the entire length of the blade.
The purpose of doing all this prissy planning and layout work is to protect the right and left side lands from being wasted unnecessarily. Newbies try to work the entire length of the blade, but this is illogical and ignores three points. The first point is that the majority of the metal I need to waste is usually located to the right and left of the land nearest the cutting edge, not the full length of the blade, so there is little benefit to grinding the entire ura. The second point is that the side lands are thin as a blade of grass and will abrade very quickly with almost no effort. Besides, without using large plates and stones, it is very difficult to work the blade’s full length accurately without wearing notches in the side lands anyway. The third point is it makes no sense to try to grind down the land nearest the neck since the plane of the ura hinges on this land. Best to leave it alone and focus my efforts where they will make a difference.
Plane blades don’t even have a land near the head, so the futility of working the entire ura on plane blades is even more obvious than for a chisel.
Work the Plan
The traditional Japanese tool used to flatten and/or correct ura is a smooth steel lapping plate called a kanaban, meaning “metal plate.” To use it, carborundum powder and water are placed on the plate, and the blade is lapped. This is not a difficult process at all, but there is a tendency for the blade’s perimeter to be ground more than the interior areas as the grit is forced in between the kanaban and the blade’s perimeter. To avoid this tendency, and to speed the process up, I prefer to use diamond plates instead of kanaban.

Whatever plan you developed, and whichever tool you selected for this job, the time has come to work the plan. Do you need more medicine? A bigger coffee cup?
First, color the ura’s perimeter lands with a marking pen or Dykem to help you see where the ura is being ground down. Don’t ever guess.
Place the most pressure on the focus line selected above. Move the blade back and forth (not side to side) onto and off of the diamond plate or kanaban with the cutting edge and the focus line always touching the diamond plate or kanaban. Don’t go past the high point for now. Be careful to not grind a notch into the narrow side lands where they meet the edge of the diamond plate or kanaban. Most people make this mistake at first.
Grind the ura down so the line at the highest point and the cutting edge is fairly flat.



Remember, the narrow lands at the sides of the hollow-ground urasuki will abrade down quickly. And the rest of the ura can be gradually flattened during subsequent sharpening sessions using regular sharpening stones. It doesn’t need to be made perfect immediately. What matters most is the steel on the land right at the cutting edge.







Polish a blade’s ura up to the level of your finest finishing stone once, and don’t touch it with rougher stones again unless it is absolutely necessary, or further gradual flattening is required. This means that in normal sharpening sessions you must remove all the damage at the cutting edge by abrading the bevel with the rougher stones, and only when the bevel is ready for the finish stone, do you work on the flat or ura, alternating from bevel to flat/ura until all defects, burrs, and even visible scratches are polished away.
If you condition the flat (ura) side of the blade correctly, and keep it polished, you should not need to work it on anything but your finish stone until it is time to tap out and grind the ura or back in the case of plane blades. Therefore, the bevel side of the blade is where we spend most of our time and effort.
Now that the ura is in good shape, we will look at sharpening the other side of the wedge, the blade’s bevel, in the next post in the series.
YMHOS
Links to Other Posts in the “Sharpening” Series
Sharpening Japanese Woodworking Tools Part 1
Sharpening Part 2 – The Journey
Sharpening Part 3 – Philosophy
Sharpening Part 4 – ‘Nando and the Sword Sharpener
Sharpening Part 5 – The Sharp Edge
Sharpening Part 6 – The Mystery of Steel
Sharpening Part 7 – The Alchemy of Hard Steel 鋼
Sharpening Part 8 – Soft Iron 地金
Sharpening Part 9 – Hard Steel & Soft Iron 鍛接
Sharpening Part 10 – The Ura 浦
Sharpening Part 11 – Supernatural Bevel Angles
Sharpening Part 12 – Skewampus Blades, Curved Cutting Edges, and Monkeyshines
Sharpening Part 13 – Nitty Gritty
Sharpening Part 14 – Natural Sharpening Stones
Sharpening Part 15 – The Most Important Stone
Sharpening Part 16 – Pixie Dust
Sharpening Part 18 – The Nagura Stone
Sharpening Part 19 – Maintaining Sharpening Stones
Sharpening Part 20 – Flattening and Polishing the Ura
Sharpening Part 21 – The Bulging Bevel
Sharpening Part 22 – The Double-bevel Blues
Sharpening Part 23 – Stance & Grip
Sharpening Part 24 – Sharpening Direction
Sharpening Part 25 – Short Strokes
Sharpening Part 26 – The Taming of the Skew
Sharpening Part 27 – The Entire Face
Sharpening Part 28 – The Minuscule Burr
Sharpening Part 29 – An Example
If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or profitably “misplace” your information. Honest Injun.
Excellent information there Stan I have learned one very important point from it, thank you
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You are welcome. Was that point to use a coffee cup to measure medicine?
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Hi Stan
Yes that too Stan haha!
The important point was to measure the flatness of the back of the chisel/plain first and make a plan.
I had up until now only flattened the first inch or so of the back using the black marker method.
Regards,
James
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James:
Now I understand.
Yes, measuring beforehand is often overlooked, and I find few people think to make a plan. It’s human nature: I know I’ve failed to do it too many times. So many times, in fact, that I decided long ago to take pity on the poor chisels and check and plan before grinding. It feels counterproductive but saves time and effort and valuable steel in the final analysis.
I have had customers buy nice chisels that were entirely usable, although not perfect, and instead of gradually truing the ura over multiple sharpening sessions as I suggested, they decided they would grind! grind!! grind!!! to try to make them perfect before even using them. Then they complain about it being soooo much work that took soooo much time. Looking at their results, Its obvious they entirely ignored my advice, made no plan, and didn’t improve anything. Instead they wasted their time (and my time) only making things worse, practically ruining the chisel in the process.
We all learn a little more everyday. We all mistakes, especially me. Ergo the coffee cup method of applying medicine. I hope this post will help our Beloved Customers (sacred in every way!) learn a little faster/sooner and make fewer mistakes. Tools need love to, donchano.
Regards,
Stan
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Oh boy. Now we get to the meat and potatoes.
This is some excellent advice. Much better to learn this way, rather than trial and error (don’t ask me how I know).
It is interesting that you suggest to work the chisel back and forth rather than side to side. It makes sense to me but I don’t see many people suggesting it. I might have to go back to that approach.
I’ve got some chisels that I have flattened as best I can. But I’m guessing there is no harm reassessing them and, if needed, following your advice – even though they are not new.
Please keep the posts coming.
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B.
Thanks for the kind words.
Are the chisels behaving themselves? Give them a kiss for me (on the handle!)
Working the blade on and off the stone lengthwise is not the only way, of course, but I find it works quickest, with the least number of strokes, when truing the ura, while minimizing the tendency to dig “notches” in the narrow and delicate side lands and wear out the ura prematurely. Even when I move the blade’s ura side to side on the stone, as in the case of plane blades, I still move the blade on and off the stone/plate. It turns into an elliptical movement sorta, kinda, almost, hardly.
The anal retentive types focused on making the ura uniform and maximizing the blade’s beauty will apply thin tape over the side lands so they don’t even touch the stone. I think they stole the idea from sword sharpeners. Much too fussy for me, but it works.
Meat and potatoes indeed. The next post in this series will be heaped with Death Adder chili peppers that will cause brain damage in a lot of people. I can imagine their heads popping like zits as they read it! Gotta get my 4k video camera ready.
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Yes, but I am not of a mind to kiss them. I just hold them. Lovingly. When I’m not even working.
I have used tape on a kanna blade but not on a chisel.
I have also seen wax (ibota?) used to prevent the lands wearing on the stone. I’m somewhat obsessive so that appeals to me. But I’m trying to fight it.
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Interesting…. I had not heard of the wax technique. Doesn’t it gum up the stone’s surface and slow thing down? Or is that the idea?
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Not sure how to reply to your comment below. I think the wax does gum up the stone’s surface and then it’s removed with a flattening stone. But I’m working with a google translation. I can’t speak to its efficacy. But it is interesting.
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Thanks. I will keep my ears open about this.
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Wow! That’s a first for me.
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That must have taken days. How much hagne would be left? Oh well, at least the bevel would have been quick to work on.
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