Thread: Naniwa SS 10k vs. 12k

I have both stones, I have never really payed attention to the scratches the 12k Leaves as I finish on naturals.
I know that 12k gives a very nice shave and really with .5 diamond spray (what I prefer to CrO) give a really nice edge.
My current progression is up to 10k SS then natural, I do not use the 12k anymore because I do not see any benefit from it in this progression.

I did not know about this rumor, but from knife sharpening experience... I think I know the EXACT answer to the 12 K leaving "deeper" scratches issue.

The scratches are not deeper, its just when you reach a certain level of polish, scratches that were put on the bevel from the more coarse hones suddenly become more visible.

This is a common thing. I first discovered this with using the Edgepro Apex: you get a crazy mirror polish with the 3k polishing tape, but if you use the 6k tape, all the sudden the bevel looks scratchy, even though its a much finer abrasive. This happens with just about every super fine abrasive I have used, and I even see this with the 10k over an 8k sometimes. Occasionally you will do a super job and you won't notice this. The 12k is polishing SO highly that, you are now seeing older scratches! IMHO

Stone grit is only nominal value. Every stone contains smaller and bigger abrasive particles. Produce finer stone is more difficult. Companies standards are tolerant to higher incidence of bigger abrasive particles for finishing stones. So finer stone can produce less consistent surface than coarser stone.

I see... well I just figured i'de share my experience is all. I've had this happen with quite a few different brands. Seems to happen with all of them once you get to a certain level of polish.

Originally Posted by atercz

Stone grit is only nominal value. Every stone contains smaller and bigger abrasive particles. Produce finer stone is more difficult. Companies standards are tolerant to higher incidence of bigger abrasive particles for finishing stones. So finer stone can produce less consistent surface than coarser stone.

What? So 12k stones are not 12k? Why then would they call it a 12k stone?

I do believe you are confusing synthetic stone with Natural stones, which by the way have no grit rating for the reasons you cited.

12k stones are 12k grit size or smaller, not larger, otherwise why would anyone buy them?

There are lot of rumors floating around, have you heard the one about tape ruining straight razors?

Originally Posted by Euclid440

What? So 12k stones are not 12k? Why then would they call it a 12k stone?

I do believe you are confusing synthetic stone with Natural stones, which by the way have no grit rating for the reasons you cited.

12k stones are 12k grit size or smaller, not larger, otherwise why would anyone buy them?

There are lot of rumors floating around, have you heard the one about tape ruining straight razors?

I wrote about synthetic stones. It is not possible check every abrasive particle in every stone. Read following document: http://www.engis.com/pdf/Particle-Si...s-summer07.pdf, chapter "SPECIFICATIONS FOR PARTICLE SIZE DISTRIBUTION ...".

Syntetic stone is not consistent but much more consistent than natural.

I have been honing now for several years using the Naniwa SS 1-3-8-12K sequence and it has worked very well for me. The 12K stone leaves a really nice, silky edge that shaves well, assuming good work was done on the 1K.

Really I agree with whoever it was who said it's 90% bevel. The bevel sets the absolute limit on how well an edge will shave. The final stones control more how that edge actually feels.

I fail to see where you reach that conclusion.

Yes, possibly with cheap stones that may be an issue, but that is partly what you pay for in a quality synthetic stone. And I am sure quality stone manufactures demand a higher level of consistency that could easily be accomplished, by running the grit though the sieve multiple times.

Otherwise why would anyone buy such a stone, if it contained higher grit size than advertised?

Your assumption is not what I have experienced in practical application. Modern quality, synthetic stones are very consistent, quality sanding papers and lapping films even more so.

Sieves are used for 60um (jap. synt. stone #320) and bigger particles. For smaller particles are used cyclone abrasive separators.
The separators can not completely ruled out larger particles. Factories milling and separation of abrasives are not exactly clean environment. Very pure sized abrazive would be too expensive.
Determination of particle size in the samples is not so simple. The methods used are sieves, sedimentation or computer analysis of microscopic images. Error measurement ranges up to 25%. Not only can not be separated abrasive, but not often to find out exactly how well they are separated.

Deviation of bigger particles is often small for razor sharpening. Eg. JIS #8000 (FEPA F 2000) mean particle size is 1.2um +/-0.3 and up to 3% of particles from 1.5 to 3.5um particles.

I purchased synt. stones with this error because they are cheap and available. Do you have better option?

Sounds like you have read a lot on the subject, but not what I have experienced in practical application.

If 25 percent of the grit of stone were larger grit than the grit rating of the stone, I would return it.

I have stones for all the quality synthetic manufactures and I am not seeing that, just the opposite. If that is what you are experiencing, buy better stones or try lapping film.