Jnat noob PSA - making mud

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Pie

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Last night I tried to do some work on a super hard ozuku using shobu and kuro nagura. I’m a completely new to proper jnats, although I’ve spent some time on cheap amakusa and binsui (much, much more forgiving). Had one hell of a time getting mud, let alone getting the nagura to actually rub the base stone without catching/stuttering/sticking/scratching. A few things I figured out, right or wrong -

1. Don’t use too much water. Moist surface and a couple drops of water seems to allow more friction, less “skating” on a thin layer of water. This was a significant development, I’m used to starting with a big pool of water on synthetics as they (mostly) slurry themselves.

2. Flatten your stone. Like dead flat. Out of frustration I tried the naguras on my kitayama, which I thought was pretty flat. Not flat enough. The nagura would simply catch and chatter. Feels like a triple plate race clutch for those who drive standard. Bad feeling. Once flattened, behaved much better and was able to produce mud with less drama.

3. Try not to slip the nagura over the sides of the base stone - I was wondering where all my wonderful mud went, and found it on the sides of my stone.

Please keep in mind this is all new to me, just noticed a couple things that really changed the game in terms of getting started on jnats. Experts, please correct me if any of my findings are incorrect or if you have anything to add. I feel like a baby trying to learn how to walk.
FE9F7BB1-ACF5-4084-B988-7539F38F843F.jpeg
 

cotedupy

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I think point 1 especially is very important. Obviously different stones will be slightly different in this regard, and you'll learn what's best for yours (as you have already). But I find with the few that I have - if I want to work with mud then a very small amount of water initially, and once you've got a little slurry going you can start adding water in larger amounts, and work it up. Too much water initially means you'll get nowhere.

That is if you want mud... I quite like it, and find it reassuring. But it's probably not necessary, and your stone will do different things without it. Did you try it without slurry too?

(p.s. I'm not an expert here either, and don't know about your type of stone. Others I'm sure will have more informed opinions)
 

DHunter86

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You got it right in that water/slurry management is very important for very hard stones.

I'm assuming you have a diamond plate to flatten the stone. To what grit did you condition the surface? From my limited experience, super hard Ozukus aren't easy to use, that's for sure. And they don't polish well - sharpening (i.e. edges) is where they'd shine.

Another slurry to try is that which you get when flattening the stone with the diamond plate (this slurry would start out typically coarser than what the stone is capable of).
 
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Carbondx

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Personal opinion:
1. Water management depends on type of stone and hardness of it.
2. Flat is a plus, but a dead flat surface will cost you $ as you are wasting out lots of your jnat. Personally I sharpen/polish on the uneven part of the stone to make it reasonably flat.
 
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Pie

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I did try it without slurry, polishing was nigh impossible but edges were doable. Personally I do like mud on this stone, it’s hard and unforgiving on its own. More experimenting with edges seems to be the direction this is going. The polish it produces is near mirror on the cladding which is a bit too smooth for me.

I actually have not flattened this thing.. I have an atoma 140 but am hesitant to use something that coarse. @DHunter86 what would you suggest?
 

jwthaparc

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Last night I tried to do some work on a super hard ozuku using shobu and kuro nagura. I’m a completely new to proper jnats, although I’ve spent some time on cheap amakusa and binsui (much, much more forgiving). Had one hell of a time getting mud, let alone getting the nagura to actually rub the base stone without catching/stuttering/sticking/scratching. A few things I figured out, right or wrong -

1. Don’t use too much water. Moist surface and a couple drops of water seems to allow more friction, less “skating” on a thin layer of water. This was a significant development, I’m used to starting with a big pool of water on synthetics as they (mostly) slurry themselves.

2. Flatten your stone. Like dead flat. Out of frustration I tried the naguras on my kitayama, which I thought was pretty flat. Not flat enough. The nagura would simply catch and chatter. Feels like a triple plate race clutch for those who drive standard. Bad feeling. Once flattened, behaved much better and was able to produce mud with less drama.

3. Try not to slip the nagura over the sides of the base stone - I was wondering where all my wonderful mud went, and found it on the sides of my stone.

Please keep in mind this is all new to me, just noticed a couple things that really changed the game in terms of getting started on jnats. Experts, please correct me if any of my findings are incorrect or if you have anything to add. I feel like a baby trying to learn how to walk.View attachment 130564
Saw you post in the discord (if that's you, I think it is)

Anyway. One bit of advice that helped me with naguras was you do not want then to be flat at all. You want a curved surface. It stops the nagura from sticking.

Convex the nagura on a diamond plate the same way you would convex a knife. Then when you are scurrying your stone do a similar motion.
 
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Pie

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That was daemon! Although now it looks like we’re stone twins.
🙏 Awesome advice tho, I was considering scoring it but convexing sounds like a much better (and less scary) proposition. Can’t wait to get home from work to try this out
 

rogue108

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I am new to Jnats but thanks to a mentor I got some great advice. The other thing I learned about mud was to move the knife around to different areas of the stone where it was fresh, not used to sharpen on yet. When I stayed in one area to long it began to polish the jigane and lighten the contrast I'd gotten earlier. I assume this was due to the stone particles getting finer as the I continued to polish over it. Someone correct me if I'm wrong.
 
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DHunter86

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I actually have not flattened this thing.. I have an atoma 140 but am hesitant to use something that coarse. @DHunter86 what would you suggest?
Feel free to use the Atoma 140 to flatten it. Then use a nagura to condition the surface before use. #140 grit diamond plate conditioned surface is definitely a waste for this stone since it's so fine, same with the resultant slurry from the #140 diamond plate. Of course, if that's all that you have, it would still work, but will take longer to refine the slurry.

Regarding naguras skidding: this is something I've yet to try but have heard to be effective - keep the nagura flat (max surface for max efficiency), but add some deeper grooves to prevent it from sticking to the stone.
 

runninscared

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Feel free to use the Atoma 140 to flatten it. Then use a nagura to condition the surface before use. #140 grit diamond plate conditioned surface is definitely a waste for this stone since it's so fine, same with the resultant slurry from the #140 diamond plate. Of course, if that's all that you have, it would still work, but will take longer to refine the slurry.

Regarding naguras skidding: this is something I've yet to try but have heard to be effective - keep the nagura flat (max surface for max efficiency), but add some deeper grooves to prevent it from sticking to the stone.
for me there is nothing worse than having a very flat nagura and a very flat stone. the stiction drives me nuts. and i hate cutting grooves in nagura. ive had the best luck just convexing all my nagura. never any stiction and the slightler lesser contact area with the stone allows the nagura to release slurry easier. you just have to be careful not to go nuts on the pressure or you just end up scratching your jnat.
 

lemeneid

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I don’t like diamond plates or unknown nagura a. The best mud produced for me is from sandpaper strapped to a sanding plate. Just slightly coarser in grit than the stone you are lapping. Other benefit of sandpaper is you don’t need a totally flat stone or have any slippy sliding naguras to deal with.

Coarse diamond plates gouge out large particles and take time to break down, plus it can leave the stone scratchy over time. When you use sandpaper that is as close to the grit you are starting on, you start with fine particles.

The other alternative would be a tomo nagura that is similar to the stone you are working with, or even broken off from the same stone. As it gives you the same starting grit particles.
 
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DHunter86

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@lemeneid, from my experience, sandpaper usually leaves loose abrasives after use. These don't break down and affect the overall grit of the slurry. One loose particle and there's a streak - back to foundation work in a fine polish... :(

May I know which sandpaper brands you use that have abrasives that don't dislodge at all?
 

lemeneid

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@lemeneid, from my experience, sandpaper usually leaves loose abrasives after use. These don't break down and affect the overall grit of the slurry. One loose particle and there's a streak - back to foundation work in a fine polish... :(

May I know which sandpaper brands you use that have abrasives that don't dislodge at all?
Sandpaper does dislodge, that’s why you should match your sandpaper grit as closely to the stone grit you have, that way your scratch pattern is as uniform, even with a stray particle.

The other trick is to keep stacks of worn sandpaper. I’ve got stacks of those left over from honyaki polishing. Worn sandpaper does not dislodge so easily and far more consistent in polishing than fresh in my opinion.

Never bothered with brand of sandpaper, I’ve always gotten whatever was available from the hardware store or the cheapest one online. And never had any problem with stray scratches while polishing.
 

Pie

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I’ve convexed a nagura now but haven’t had the chance to test it out. I too dislike the idea of scoring my natural naguras, although I did do it to a synthetic one and it works great, zero stiction issues. Might try that sandpaper route if the atoma mashes the ozuku. Thank you all for the advice!
 

runninscared

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I’ve convexed a nagura now but haven’t had the chance to test it out. I too dislike the idea of scoring my natural naguras, although I did do it to a synthetic one and it works great, zero stiction issues. Might try that sandpaper route if the atoma mashes the ozuku. Thank you all for the advice!
just make sure when you use the nagura that you use it in a way that preserves the convexity so you dont have to take it back to a diamond plate/sandpaper to re-convex it.
 

tri.ngm

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I have a noob question.
When using a Nagura to raise slurry, sometimes it gets quite sticky. Is it normal and if not, what do I do wrong?
 

jwthaparc

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I have a noob question.
When using a Nagura to raise slurry, sometimes it gets quite sticky. Is it normal and if not, what do I do wrong?
Convex the nagura on a diamond plate, and then when you are raising slurry use the same motion you used to convex the nagura on the stone.
 
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