Sharpening Part 14 – Natural Sharpening Stones

Advice is a dangerous gift, even from the wise to the wise, and all courses may run ill.

J.R.R. Tolkien

We receive a lot of inquiries about natural finishing stones, so your humble servant wanted to share some accumulated thoughts and experiences about them with Beloved Customer. Perhaps they will be useful.

To begin with, natural Japanese stones are a lot of fun, and can create a beautiful, cloudy finish on a blade’s bevel. They truly make my heart sing, wild thing.

I believe that blades finished with a natural stone tend to stay sharper a little longer compared to synthetic stones, but can’t prove it. Despite my fondness for them, I want to make it clear that natural stones are not magic, and are not critical to doing good work.

It is interesting to note, however, that while top-quality natural stones are expensive, if judged by the amount of steel they can sharpen, they are actually no more costly than the better synthetic stones. But they can be more of a gamble.

Geologists believe (they weren’t around at the time to witness the event, although they like to pretend they were) that natural sharpening stones typical to Japan were created when particles of volcanic dust fell from the sky, were sorted, and sifted by winds and waves, and settled onto the sea floor eventually becoming sedimentary stone. Sounds likely.

Being natural, they carry the inherent and potentially expensive risk of internal defects, such as weakness between sedimentation layers, cracks, and contamination such as hard particles of sand concealed inside. Even if you find one that seems perfect in every way, the bones never stop rolling because you never know what lurks inside.

Your foolish servant erred with his first purchase of a natural stone, one recommended by a hardware store owner in Sendai many years ago. I fear he intentionally foisted a low-quality stone on me that a person more experienced with natural sharpening stones would have rejected. This stone “drags” steel, a phenomenon where the stone deposits hard clumps on the blade that then gouge the stone’s surface and leaves rough spots on the blade. It’s impossible, BTW, to judge a stone’s propensity for this pixieish behavior by eyeball alone.

I learned a bitter and expensive lesson about both natural stones and salesmen that day. I still use that stone for sharpening axes and gardening tools and as a door prop, but the real reason I keep it around is as a reminder of my foolishness.

After that disastrous adventure, I became more careful, pay less attention to what people say or even write, and distrust salemen like thin ice over a rushing river. Consequently, I don’t give a rodent’s ruddy fundament about most people’s opinions on the subject of sharpening stones. Nearly all who claim expertise talk and write about things they only partially understand. Many have a conflict of interest. Still others seek justification of their poor decisions.

Nor I do care about the region or mountain or mine a stone came from, or its designation or color. A word to the wise a stone seller near Kyoto whispered into my shell-like ear some years ago: Even the best mines produce mostly waste.

And because of the impossibility of evaluating stones long-distance, and considering Gildor’s wise words quoted above, I am hesitant to give advice about what stones to buy or where to buy them. But I will tell you what I do when buying a stone:

1. I examine the stone for cracks and signs of irregularities and impending separation at its sides (not all defects are fatal);
2. I flip it with my fingertips and listen to the sound it makes. Yes, a good stone sounds different from a bad stone;
3. I take the stone in my hand, close my eyes, and feel it with my ki 気. Does it feel sound and happy?;
4. I touch my fingertip to my tongue, wet the stone just a bit, and smell it. Does the moisture soak into the stone quickly, or is the stone too dense? Is the smell clean or muddy?
5. I touch it to my teeth (an ancient technique for detecting the fineness and consistency of a stone’s abrasive qualities);
6. I put a plane blade I know well to the stone, take a few strokes, and like a bow on violin strings, I feel the friction and listen to the music made;
7. I examine the scratches the stone leaves on the blade’s jigane and hagane using a loupe. 

None of these critical tests can be conducted long-distance. BTW, if you think any of them are pointless, then I know where you can get a good deal on some swamp land in North Korea with its own lake perfect for a condo development. Well, actually its a settlement pond for a chrome plating factory, but the effluent discharge was recently brought up to 1876 standards so there is no pesky vegetation, or endangered fish or wildlife to deal with, and the price is right!

I have two natural stones I use regularly nowadays. One is of medium hardness suitable for most every straight blade. The other, pictured below, is very soft, and easily damaged, but creates a beautiful foggy finish on the steel. 

I love my natural finishing stones, the feel of using them, their smell, the music they make and the pretty finish they produce on my blades. They are part of the romance unique to Japanese blades. I believe the stones I use now and their sisters worn to slivers in past decades were worth every penny I paid for them, but I recognize this is an emotional rather than practical viewpoint, and difficult to defend economically.

Don’t misunderstand: your humble servant is not suggesting you should not try natural sharpening stones, only that you carefully evaluate them in-person beforehand, and buy from a reputable dealer that offers a reliable warranty (please don’t ask for recommendations). And just to prove I am neither troll nor curmudgeon, I will give you the same advice about purchasing natural sharpening stones that a wise old man shared with me a long time ago, advice that has passed Gildor’s test.

• Rule 1: Don’t trust your eyes alone when judging a stone’s origin, designation, appearance, or performance (see the five tests listed above): always try a blade on the stone before purchasing it to make sure it works for you and your blade;
• Rule 2: Don’t buy a stone from someone you don’t trust and who won’t give you a reliable 30 day warranty to provide time to check the stone carefully for suitability and defects. Remember, the combination of stone and blade is much like a marriage where the softer (but actually granularly harder) stone smooths and polishes the harder blade. If the two don’t work well together, then even lawyers can’t make it right, but a warranty may help reduce the damage;
• Rule 3: Don’t whine if the stone disappoints: roll the dice and smile at the spots they show you. Besides, hoes, axes, and hedge shears need sharpening love too.

On the other hand, if you have the stomach for Rule 3 and don’t mind risking your money, then the first two Rules can perhaps be ignored. I grew up in Sin City and know that can be fun too. You pays your money and you takes your chances; Baby needs a new pair of shoes!

Finally, if and when you find the perfect natural sharpening stone, I advise you to protect that lovely thing from damage to ensure it serves you long and reliably. The link below is to an article on this very subject: Protecting Natural Sharpening Stones

YMHOS

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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 17 – Gear
• 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
• Sharpening Part 30 – Uradashi & Uraoshi