Thread: Gokumyo 20k consistency

I've had this hone for about 4 months and honed/touched up about 3 dozen razors with it.

Mine was not affixed to the base and so I have been using the "bottom" side to leave the stamp untouched.

I have found that the amount of swarf produced seems to vary from quite alot (for a 20k) to virtually none. The resulting keenness of the edge seems to vary as well.
I always lap with an Atoma 400, and it is definitely faster with a bit of slurry left behind, but I have not found this to improve the keenness.
I have tried using the 3k/8k rubber that came with it and this dramatically increases the swarf production, but I am nearly convinced that it is simply embedding coarse particles in the stone as the edge always seems to be set back when I have tried this.

Now, yesterday when I was lapping prior to touching up a couple of razors I noticed that there is a variation in the colour, a white band 5-7mm wide has formed on one edge and there is a hint of one forming on the other. The center region of the hone is very slightly yellow, and looking with a loupe I can see a mottled appearance. I need a better camera to show this, it is very subtle.

My thought is that I need to keep lapping and see if the center region continues to shrink. Judging by the chamfer on the edge, I have removed about 1mm since receiving the stone. The peculiar thing is that I feel like I had better results with the first few razors I honed.

Has anyone had similar experience?

You have to be absolutely sure the stone is flat. The Gokumyo 20k is a pretty hard stone that can take some time to lap fully. Second you want the surface very smooth, 400 grit scratches is way too coarse. I smooth mine with a coticule and the results are super consistent no matter maker, steel or grind. I do not get any swarf with mine as it should be expected from such high grit stone. I think as soon as you smooth the surface to be like mirror you will not see swarf anymore.

+1 on mainaman's post. I do three lappings on my 20k. Atoma 400, Atoma 1200 and finish the surface with a DMT 325.

Also because of the 20k hardness, each different razor may require a different number of strokes to refine the edge. You need to experiment.

I think I wasn't clear, my concern is that the surface is not uniform in appearance. The edges are pure white and the center is slightly off-white and mottled. I have the feeling that there is a layer or skin of bad material that has "settled to the bottom" during manufacture.
I guess my options are to keep lapping the backside or start using the top. Just wondering if anyone else has experienced this.

I think that smoothing/polishing the stone surface will improve your chances of a better razor edge. Try a coticule like Stefan suggested.

Honestly, I would ditch that whole backside concept.
Take a picture of the stamps, then flatten it and use the intended side of the stone

And as the others has adviced, go to a finer stone for last polish of the stone's surface.

Talk to your vendor about the colouration issue. If it was/is someone like Stu, chances are they'll either know what it means or they'll follow it back to the manufacturer for you to get an answer.

Personally, I would expect a high-end synthetic to be reasonably uniform throughout but I don't know these stones. So your best bet is talk to the manufacturer I'd have thought.

James.

Mine is consistent in color but I don't use it very much.

I've had no issues with mine at all. Mine is white from end to end on both sides, and I do use both sides. I lap mine after every use using 400 grit wet/dry sandpaper and have experienced no issues with that either.
It has become my primary/only finisher and has displaced an Escher that I was using before. In my progression, it follows my 12K Naniwa SS and has caused my 16K and 30K Shaptons to just languish in their boxes.

I found I like the feel of the escher finish on my face/neck better than the feel of the 20k. I still need to use it more to really come to a conclusion, and I'll keep it regardless. If I'm going to sell a personal razor, or on the rare occasions when I hone someone elses razor, I'll trot it out and give them the 'scary sharp' edge.