Nanohone NL-5 diamond plate thoughts

Hi all. I have been eyeing off Nano Hone's products for a while and when I found out Pro-tooling was becoming an Australia dealer / stockist I was quite excited. I purchased an NL-5 and 50 micron Surf stone. Haven't really used the surf stone much, yet, but the NL-5 is such a great piece of kit. I use it solely for flattening sharpening stones of all kinds from low grit synthetics to high grit naturals and even an arkansas black stone.

Apologies for the sideways images again.... Surely that is an easy forum fix? The NL-5 is extremely fast cutting, has a unique diamond pattern that results in little to no friction ('suction'?) when flattening stones in comparison to my Atoma 1200 which I can barely move once a muddy slurry builds up on a stone as the surface is flattened.
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It's great for making a slurry on high grit stones very quickly, too. I'm looking forward to using the Sharp Skate BE 4 if/when that is stocked by pro-tooling.

Keisaburo Swedish steel blade on a hard tsujima medium stone. My most regularly used blade seen planing NG rosewood on a large entrance door. I think the blacksmith is more important than the steel choice.
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Atsu nomi from Sukemaru, blacksmith is Yoshio Usui White Steel 1 finished on a Yaginoshima asagi. It's great being able to flatten these stones fast and accurately as well as build up a quick slurry to aid in finishing.

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What is the purpose of the slurry of smashed abrasive particles?
I thought the water flushed away the swarf so the abrasive cuts cleanly at a predictable grit size.

From the five minutes of sharpening Japanese style class that I attended the abrasive produced is used on a honing plate for sharpening ala Shapton sharpening powder. A pinch of Shapton powder is put on a plate, a drop of water is added to it and let sharpening begin in the normal manner of using a waterstone. When the slurry produced from that is seen to be dry instantly stop sharpening and you have a very sharp blade. The slurry from a waterstone can be used on the same way so we were told but not shown.

The plate you are referring to Chris, is typically known as a 'Kanaban' in Japan. As you said, originally used with Corundum powder as an abrasive to flatten the backs of chisels or plane blades which I believe is Ura-oshi. I use some slurry from a 1000 stone instead of the Corundum powder but its not as aggressive which I prefer. You can even just clean the plate off, use a drop or two of water, or spit, which is actually a nice consistency and used by several to then lap the chisel back on and it polishes the surface well as the water dries up essentially burnishing the surface.

Leaving the slurry on a finer natural stone has several benefits aside from lubrication. On a hard stone, it takes a long time to build up a slurry. One method to quickly build a slurry is to use a nagura stone on the finishing stone surface. Rather than use the nagura, the diamond plate generates slurry containing a mixture of particles off of the finish stone that aid in cutting. I find a hard natural stone works a lot more efficiently when it has a clean slurry on it for removing the scratches from the previous stone. Not too much water in the mix, though. As the slurry is used over the stone surface abrasive particles break down into smaller and smaller particles as well as new particles being released from the stone resulting in a slight mixture of abrasive grit sizes that many believe produces a more suitable finish. Essentially like a microscopic saw tooth edge to a degree. The Japanstone on youtube has some interesting videos showing the before and after microscope images of blades / razors sharpened on several natural stones using slurry.

You can also imagine that if you use a 1200 grit plate to flatten a 10,000 grit stone there are 1200grit deep scratches on the surface of the 10000grit stone. Not 1200 grit particles but 1200grit deep 'grooves' where the stone surface isn't being utilised and a bit of the stones 10000grit+ slurry can help fill in these tiny grooves and more efficiently cut the steel. A theory, at least.

I have no scientific proof of this but having a fine slurry on a finishing stone speeds up my sharpening process a lot. Typically the finish off of a natural stone results in a 'hazy' appearance rather than a glossy or mirrored surface that you'd typically get on a synthetic 10000 grit stone. This is due to the fact that natural stones consist of varying particle sizes due to their sediments and depositional environment compared to the extremely controlled grit size on a man-made stone. I like the hazy appearance and can not complain with the cutting ability. I have some images on the edge at 100x zoom after working on a slurried medium stone. I will dig them up.

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I should note between stones the NL-5 is always washed clean with water to ensure no contaminating the next stone with lower grits.

The talk and demonstration by a Japanese gentleman from Canberra primarily showed using Shapton powder which I was given a small sample of thanks to Japan Tools who held the demonstration a few weeks ago. I have yet to try it not needing to sharpen recently but I have tried Carborundum powder on cast iron plates which I thought worked very well and I am interested in seeing how the Shapton powder compares. I posted a link to these talks at Japan Tools Australia in the Japanese Tools forum, they are free and a good intro to Japanese tools and sharpening.