Suehiro Gokumyo 20k

Gok 20 Stacked 1

 The Suehiro Gokumyo 20k synthetic waterstone 

The 20G features a hard ceramic binder and a particle size of .5µm. As I’m writing this – I’ve had this hone for a good while now, and I’ve been giving it a lot of attention. 

The packaging is fairly impressive. The cardboard box is large and quite sturdy. Inside there are two compartments – one to hold the stone and the rubber honing platform, and the other is for the fancy rubber stone. 

Lapping the 20G on the Atoma 140x went easy enough, and cleanup on the 400x Atoma was similarly simple and nearly effortless. Some have said this stone is super hard. To me, it seems hard – but not unusually so. It’s hard enough to wear well with use, which is all we should expect here. The feel of this stone is more like plastic than stone; I know it’s a synthetic and I’m not trying to pretend otherwise. But the overall feel is decidedly more ‘fake’ than ‘real’ – it has sort of hollow feeling that’s hard to put into words. Better living through chemistry I guess. Hah. 

The Gok 20k comes with it’s own custom fitted rubber stand/holder, and a very fancy 400x rubbing/dressing stone with a handle. Personally – I’d like to see those extras removed in favor of a lower price-point. While the stand is functional, it’s not essential for me. The rubbing stone is a good thing, but, IMO, it’s overdone; a simple slice of stone would suffice. However, the packaging is part of the price of admission and both extras do make for an impressive presentation while being totally usable. 

I ran a couple of test blades across the Gok just to get an idea of what I should expect.  My first thought was that this stone is dead; the feedback was pretty lame. Looking at the bevel of the test razor shows a very high ‘mirror’ polish.  


Honing/Shaving Tests 

Test #1; bevel set on 1k C, followed by Jnat/Nagura progression, then shave tested and proven to be a winner. Then a short touch-up followed by 20 laps on the Gok.

Result – edge was set back, it was notably rougher and not as sharp. Fail. 

Test #2; same razor as above; new bevel set on a 1k Chosera. The post bevel work was a typical Jnat progression; Botan, Tenjyou, Koma, Tomo on a Shobudani Asagi. Then – 20 laps on the Gok 20k. While similar to the previous test, I’m removing the initial shave-test to remove one variable.

Result – The edge shaved, but same as above. Fail. 

Test #3; same razor as above; edge brought down to new bevel on a 1k Chosera. Followed that with 3k and 5k Naniwa Specialty Stones. The pre-finish was done on the 8k Jyunpaku and the final finish was executed on the Gok 20.

Result - The shave from this honing effort was on target; the edge was keen and smooth. The surprisingly excellent 'face feel' lasted a very long time. Honestly, while shaving, I very nearly forgot this was honed on synthetics. I’m not saying the edge was identical to one from a Jnat or Thuri or better or whatever. No – not that at all. What I am saying is that the typical synthetic feel was greatly diminished; sort of like having a 12k SS edge that's been 'smoothed out' while possibly bumping up the 'sharp' a bit. 

Test #4 – Same razor as above; the bevel was reset on the 1k Chosera, refined on the 3k & 5k Specialty Stones, and the pre-finish work was started with the 8k Jyunpaku and then the Gok 20. The final finish was executed with Tomo Nagura slurry on a hard Jnat My intention is to find out if putting the Jnat work afterwards would yield a better final result.

Result – Yes – this worked rather well. The edge was good; there was enough of a synthetic fingerprint/signature on the edge that I noticed it, but it was diminished.   

Test #5 – Same razor as above; the edge was taken down to a fresh bevel-set on a 1k Chosera and then the bevel was refined with a typical Botan, Tenjyou, Mejiro, Koma then Tomo Nagura progression on a hard Asagi Jnat. The intention here is to compare this edge to the one honed previously.

Result – hands down, this edge wins for sharp and smooth. This honing progression is not as fast as following an all synthetic progression with a Jnat to finish; I would estimate that the Jnat/Nagura progression requires an additional 15-20 minutes but I could probably trim that back a bit I wanted to. Even if it’s only 10 extra minutes; If I had to hone 10 razors – that would be significant. When honing 1-2 razors, saving 10 minutes for each session is irrelevant to me – especially when I’m enjoying the honing and finished result more. 

Test #6 – same razor as above, honed from 1k – 20k on synths and proven to shave well. After a few shaves – I did a quick touchup using slurry raised with a 1.2k DMT on the Gok. 

Result - The resulting edge was harsh and uneven. I had to repair the edge on the 5k and progress back up to the 20k. Fail. 

Test #7 – used two different razors, followed the same process as above.

Result - identical to test #6 – fail. 

Test #8 – same as test #7 but generated slurry with an Atoma 1200 ‘Nagura’.

Result – identical to test #7 – fail.


Using Slurry

After some testing, I have to say that this is the last stone I’d ever use slurry on. In general, I feel that way about all synthetics finer than 1k, but here the impact was dramatically detrimental to the edge. Looking at the slurry under high magnification, it seems as though the abrasive particles in the slurry seem to want to clump together and it seems like the clumped-up mass turns into an abrasive paste. I’m imagining that this is a huge component in the reduction of edge quality. I attempted to touch up 3 different razors that were shaving well, using some slurry generated by a 1.2k DMT, and then a 1.2k Atoma  - each time was a fail. The edges were rougher and under the scope the edges showed a significant amount of damage that required me taking the razor back to the 5k.



I am not a scientist and none of the above qualifies as a scientific test. . I’m not saying that this is the final word on this stone or any honing process.

My experiences are mine, and my conclusions are derived from processing my findings from my personal experiences as I’ve outlined them. 


Errant notes. 

Most synths are ‘easy’ and ‘consistent’ - so I’m not bowled over by the 20Gs ease-of-use or consistency; it’s on par with the 12k SS in this regard. 

I do not believe the 20G is capable of delivering great edges more consistently than natural hones. 

For shits and giggles, I gave finished blade 50 x-strokes on the 20G; afterwards - I had near-zero swarf. While it’s fast like a 12k SS and it does polish the bevel very well - this stone did not create swarf like I’ve read about online. This test did put a nasty wire on the edge though – so had I continued, I would probably have seen heavy swarf trails when/if the wire broke free. 

I would not want to so more than 20 strokes on the 20G. After testing with 3 different razors; edge damage (foil/burr/wire/etc) is imminent at somewhere between 30-50 strokes.   

The 20G didn’t seem to take on any water; the initial splash of water was all I needed. That could change with lapping or use though I suppose. 

The instructions that come with the 20G show an illustration of a hand next to one of the stone. In the drawing, the hand’s palm is shaded. At one time there was some discussion about what that drawing was referring to and I thought that it might be referring to only needing to use a small bit of water. I contacted a seller in Japan about that part of instructions, and it turns out that’s exactly what it means. 



Overall – the G20 is a decent/good stone, but I don’t like the feel of using it. I could get past that if it offered a very significant improvement over a SW 8k edge, but it simply does not do that for me. Bottom line - I’m going to finish on a Jnat or whatever, and I can jump to that natural finisher from my 8k as easily as I can from this 20k. 

When honing on synths from start to finish, the resulting edge is usable enough, and it’s good for an edge off a synth finisher. But - it doesn’t deliver exactly what I’m looking for in a finished edge.

If I was going with all synths, and I didn’t have a 12k, I might consider the 20k for that spot because it does leave what I perceive to be a somewhat smoother edge than the Naniwa 12k SS or Specialty Stone.


Approx. Dimensions: 8.0 x 2.75 x 0.75 / 203 x 70 x 19 mm

Weight: 25 oz / 705 g

Gok 20 Box.jpg
Gok 20 Box End 1.jpg
Gok 20 Finish 1.jpg

© Keith V Johnson 2014 - 2018