Nagura

[Dave Zellers]

As I continue to work in my attempt at understanding the finer points of sharpening, I spent considerable time (having already spent considerable money) last evening reading earlier threads re sharpening. A fabulous treasure trove of information, most from the usual suspects and some from voices gone by. At some point I became focused on nagura. I have 1 nagura 1000 stone already for lower grit sharpening, and am curious if I need another or two.

Having embraced the concept of slurry as I watch it work on lower grit stones, at the same time I struggle with stickiness and black buildup on my higher grit stones (5000 and 12000 grit Shapton), so I have to ask if another or two nagura stones matching or close to my 5 & 12K stones is advisable. I do remember at least one voice from my reading marathon last night that nagura is not all that beneficial at the higher grits. (Winton?) Please forgive my 65 year old colander of a memory.

Anyway, I'm getting really close to pulling the trigger on a DMT 4x10 lapping plate through Amazon and that would be the time to "add on" a nagura stone or two if deemed beneficial by respectable people here.

If deemed not beneficial by respectable people or beneficial by unrespectable people, then I'll pass.

I retain all rights as to respectability and hold it in strictest confidence.

Whaddayathink?

[Malcolm Schweizer]

I bought some of those little folding diamond knife sharpeners, removed the handles, and use them in lieu of a Nagura. I also have a number of various Nagura stones, but the diamond stones work in seconds without any contamination from the Nagura. (For example, the Chosera Nagura that used to come with the Chosera stones was so soft that it ended up leaving part of the brown Nagura stone visible in the slurry. This is not an issue with a diamond Nagura.)

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[Dave Zellers]

Diamond nagura. That almost doesn't compute. But my processor is underpowered.

[Stanley Covington]

As I continue to work in my attempt at understanding the finer points of sharpening, I spent considerable time (having already spent considerable money) last evening reading earlier threads re sharpening. A fabulous treasure trove of information, most from the usual suspects and some from voices gone by. At some point I became focused on nagura. I have 1 nagura 1000 stone already for lower grit sharpening, and am curious if I need another or two.

Having embraced the concept of slurry as I watch it work on lower grit stones, at the same time I struggle with stickiness and black buildup on my higher grit stones (5000 and 12000 grit Shapton), so I have to ask if another or two nagura stones matching or close to my 5 & 12K stones is advisable. I do remember at least one voice from my reading marathon last night that nagura is not all that beneficial at the higher grits. (Winton?) Please forgive my 65 year old colander of a memory.

Anyway, I'm getting really close to pulling the trigger on a DMT 4x10 lapping plate through Amazon and that would be the time to "add on" a nagura stone or two if deemed beneficial by respectable people here.

If deemed not beneficial by respectable people or beneficial by unrespectable people, then I'll pass.

I retain all rights as to respectability and hold it in strictest confidence.

Whaddayathink?

Dave:

Your questions are vague. I assume you want our opinion on the following points:

1. The usefulness of nagura stones in general;
2. The usefulness of nagura stones when used with fine-grit sharpening stones;
3. How many nagura stones are necessary for effective sharpening.

Nagura stones are every useful. They help in a three ways: First, they can be used to abrade/dress a finishing stone, breaking up glaze, and helping to keep it flatter. Second, the nagura adds a small amount of its own, finer grit, to the face of finishing stone being used. When combined with water, this starter grit helps to quickly develop the necessary slurry, saving time and effort. Third, as wet waterstone grit is used to sharpen, especially in the case of natural stones, it is gradually broken down into finer and finer particles. The nagura grit combines with the increasingly finer grit from finishing stone to make an excellent finishing slurry superior to anything the sharpening stone alone can produce. This last benefit depends on the combination of finishing stone and nagura, however, and does not occur in all cases.

Nagura are especially effective on finer grit stones. Less so on rougher stones. I don't bother with a nagura until #6000.

A key point to remember is that the grit from the nagura MUST be finer than the grit of the finishing stone. This is not usually a problem. However, you might want to get a loupe and check that the scratches on steel from your nagura are finer than those from your finishing stones.

It is entirely possible to use commercial abrasive powders on your finishing stones instead of a nagura. If you want to match your nagura to your finishing stone, this would be the way to go. The guys at the kezuroukai tend to like this option.

I have tried several varieties of nagura over the years. I settled on two. One is a soft white stone called a Mikawa for use on my harder stones, such as for sharpening razors.

JunMikawaNagura.jpg

The second type, and the one I use the most, and for all other applications, is a tsushima nagura. This is a black stone mined from the seabed.
TsushimaNagura.jpg

I use them on all my finishing stones, whether natural or manmade with good results. I don't think you would benefit much from trying to get multiple grits of nagura to match different stones. One for hard stones and one for regular stones is plenty, IMO. If you are sharpening woodworking tools, a single nagura should suffice. There is a lot of personal preference.

Nagura are unsual stones. Despite appearances, they are not just conveniently shaped pieces of finishing stone. Besides being fine grit, a good nagura will not bond, or stick, or drag on your finishing stones, but will move happily over their surface with a little bit water. By comparison, you will notice that a piece of a broken finishing stone will not usually work well as a nagura because it will bond, stick, and even gouge the surface of another finishing stone. I don't know exactly why this is so.

Stan

[Oskar Sedell]

I second Stans comments. I like to use nagura either to refresh the surface of a courser stone and to keep it fast cutting, as well as on my fine finishing stones. I use them both on natural and man made stones. I'd like to add that I find the nagura slurry helpful when honing flat bevels, reducing the sticking of the bevel to the stone.

Regarding the problem of nagura sticking to the sharpening stone: this can be avoided by giving the nagura a slight rounding, or using a rounded corner for raising slurry. This way also hard pieces of finishing stone can be used. In this case I find patience and a light touch good, with too much pressure the surface of the finishing stone can be scratched.

[Derek Cohen]

Having embraced the concept of slurry as I watch it work on lower grit stones, at the same time I struggle with stickiness and black buildup on my higher grit stones (5000 and 12000 grit Shapton), so I have to ask if another or two nagura stones matching or close to my 5 & 12K stones is advisable. I do remember at least one voice from my reading marathon last night that nagura is not all that beneficial at the higher grits. (Winton?) Please forgive my 65 year old colander of a memory.

Dave, I have Pro Shaptons and never used a nagura on them, not even the 1000.

I think that the reason you are looking at a nagura to help you is because you are experiencing stiction on the 5000 and 12000. A nagura appears to help with the 1000 because it is much softer. The 5K and 12K have hard surfaces.

The solution is less complex than you think: use the Shaptons (all of them) with a spritz of soapy water (I just add a little liquid soap). This will not only eliminate the stiction, but it will keep the stones (and your hands) clean. I've done this for about 10 years without any problems to the stones.

Regards from Perth

Derek

[Dave Zellers]

I have read about using soapy water. I'll try that.

[Stanley Covington]

I have read about using soapy water. I'll try that.

The OP's questions were about nagura specifically, so I did not touch on lubricants.

While soapy water can be helpful, I do not believe it can replace nagura entirely. Indeed, I do not want to reduce the "friction" between my stone and blades using slippery soap because friction is useful. I do, however, want to prevent clogging, the buildup of metal fragments and dried slurry, and gouging of the stone, so water, at least, is necessary.

If you are interested in a way to make your sharpening water work better, mix washing soda, or borax washing powder, with distilled water and store the mixture in a plastic bottle. Use this to keep your stones wet during sharpening. Dilute caustic soda is even better, but must be handled with caution. Like soap, these chemicals make the "water wetter," reducing stiction and helping to reduce clogging. They also have the advantage of increasing the PH of the water making it more alkaline, and therefore less likely to promote rust. Distilled water does not have the corrosive chlorine or other chemicals found in nearly all municipal water supplies.

The problems with liquid soap are that it is too slippery, IMO, some varieties can leave a sticky residue, and it does little to prevent rust.

This is a technique used by professional sharpeners and is not suited for most amateurs.

[andy bessette]

Mal--those diamond sharpeners are what i use, in the field, for touching up an edge so I can keep working. And thy're very fast for repairing a damaged edge.

[Malcolm Schweizer]

Mal--those diamond sharpeners are what i use, in the field, for touching up an edge so I can keep working. And thy're very fast for repairing a damaged edge.

I only use them in place of a Nagura to dress the sharpening stone and create a slurry. They do, however, work well for their intended purpose of sharpening.