Excellent question, Mark!


You can see fromt he 1K Diamond picture that everything looks pretty good - minus my 2 little bumps in the edge of the edge. The scratches are consistent, and the depth of each seems to reflect in a consistent manner. The hidden scratches from coarser grits are masked by the "noise" from the reflections of light from the existing bevel. This is because the refinement isn't enough to get a clear reading of the surface, and because the diamonds scratches are still pretty deep, causing the peaks and valleys to reflect light in different directions.

1K WEPS diamond:




On the 1200 Ceramic, the depth of the scratches are more shallow, and the quality of the scratches makes a more even surface that allows for the deeper scratches to be exposed - it's a lot like looking to the bottom of a pool through a disturbed surface vs. looking down through a calm surface.

1200 WEPS ceramic:




This issue of deeper scratches being exposed happens at every level simply because each grit makes finer scratches. That's one reason I like a progression that uses more stones with smaller jumps between grits - it takes less time to smooth over the surface from the previous scratches.

However, fewer stones with larger jumps between grits really just needs more time to establish the finer grit's scratches. Keep in mind that different mediums will require different amounts of time to abrade the surface sufficiently. That's why I said that the exposed scratches could be attributed to my scrubbing not being enough.

I suggested going back to the 800 or 1K paddles because if an edge has a lot of deeper scratches, it would be more advantageous to step back a grit. But if the scratches are from a closer grit, then more time on the existing grit can often remedy the problem. I chose more strokes in this case.

There will be a point of diminishing returns, though. Don't expect your 30K Shapton pro stone to remove the 400 grit scratches any time this week.

This is an issue I've struggled with a lot. Tom is correct in that the more you polish the edge, the more individual scratches really stand out, especially under high magnification. Tom is also correct that by using a crosshatch method, not only is it easier to knock the ridges between scratches down, it's easier to see if you're removing the scratches from the previous stone. When you stroke in the same direction with every grit, you're not working as efficiently as possible because many of the particles will be fitting inside the scratches from the previous stone and won't be doing any work at all. We did a fun study of different stones last year on Knife Forums: WEPS Shapton Progression Tom started the post and it evolved into a comparative study of Shaptons vs. Choseras with a lot of stropping along the way. From the photos, it's easy to see exactly what Tom is describing in the way of deep scratches hiding under the scattered light from all the myriad micro-geometry of the scratch pattern. As you peel back the metal to get closer to the scratch valleys, you're able to see them more clearly. During this study, I re-learned something I had really come to know in the knife sharpening competition: when stropping, USE VERY LIGHT PRESSURE! It was astonishing how deeply the abrasives dug in when using too much pressure with the strops.

Josh - You've got a really tough problem Unfortunately, I'm not sure what the root of it is without seeing the actual edge.

The good news is that from the sound of things, it looks like the sharpening aspect is working since you were able to get it sharp. Often times on razors you still see scratches without any magnification, but they won't necessarily hinder the overall performance.

The fact that you aren't getting rid of the scratches with 700+ strokes with the 14 micron paste leads me to believe that it is the razor and/or the steel quality. Sometimes during the factory hollow grinding, the scratches may run really deep - so deep that getting them out completely is not worth the amount of metal removal needed. Sometimes that stainless steel is pretty hard - Gold Dollar Razors are notoriously poorly made, but can be fruitless to abrade with only the lightest touch.

At this point I would try using a little more pressure on the strops.

A USB scope would definitely help in diagnosing the problem. I always recommend the Veho 400 since it is pretty inexpensive and if a bunch of guys have the same scope, we can all see what we're talking about.

Thanks Tom and Clay! I finally understand the issue .

I have read the entire thread at Knife Forums. I had read bit and pieces of it before, but never the entire thread! It should be mandatory for every WEPS user . If I had done so, I wouldn't have asked this question in the first place. And now I understand the issue, I see it appear everywhere, including on my own knives, even at much lower grit levels (my highest grit level stone is the ceramic 1600). The consequences are just not so bad at lower grit levels.

Any tips on how to conquer this other than spend enough time with higher level grit stones to remove the scratches from lower level stones and using the crosshatch method to make such scratches easier to spot?

Clay, if the stropping compound digs in too deeply, why not use a less abrasive compound of the same micron size, e.g., chromium oxide instead of diamonds? Or (but maybe this is a very stupid question) strop without any abrasive compound at all?

That was a great thread on knife forums - and when the whole "underhoning" issue was still a rather new concept. Thanks for posting that link, Clay!

Mark, the best way (IMO) is to really spend time at the medium grit levels - more than you would think. I generally do enough strokes to make it look good under the scope, then I do a bunch more. You can't do too many strokes here, but you need to lighten up on the pressure to make sure you don't cut too deeply.

There is also what I call a "critical leap" in any progression, which is the transition from medium grits to fine grits. The medium grits will always abrade, but the surface of the bevel will always have those higher peaks and valleys. On the finer grits, the stone is no longer aggressive enough to create such high peaks and valleys, and the surface becomes much flatter as a result. That is when all the previous work will either pay off, or show the flaws.

On the stock WEPS, it the critical leap is between the 1K diamond and 1200 Ceramic. On the Choseras, it's between the 5K and 10K (it's also arguably between the 3K and 5K - but that's another story!) On the Shaptons it is between the 2K and 5K.

I'll let Clay answer the other question

Josh - I'll try to get a progression with the pastes. I may need a few weeks - though.

mark76 wrote:


Great questions Mark. I've fiddled about with lots of different compounds on the strops and finally settled on diamonds for efficiency. As long as you keep the pressure light, they don't dig in too much. I've had some nice results with Chromium Oxide and Boron Nitride, but they are very messy to use and don't work as quickly as the diamonds. Stropping with plain leather works well. Leather has the unique ability to burnish the metal surface while honing the edge. Adding a micro-abrasive accelerates the process of of bevel and edge finishing, giving you a 3-in-1 punch.

razoredgeknives wrote:


In reading this, a question comes to mind about contamination on the strops. I'm guessing you keep them pretty well protected, but if they've picked up metal filing and/or sloughed of diamonds, they could easily dig big scratches.

OK! Chosera WEPS microscope progression is up!

jendeindustries.wordpress.com/2012/02/25...oscopic-progression/

I touched on the concepts of the critical leap and the difference between a paste and a slurry.

Enjoy!

Thanks Tom.
That's amazing.

I have a question. Since I have the diamond/ceramic stones through 1600
and the Chosera 2000 is close to the Ceramic 1600,
would you suggest that I continue the progression, after the Ceramic 1600,
starting with the Chosera 2000
or would it be better to back down to the 1000 or even lower?

A couple more posts and we are all ready to start our professional sharpening businesses .

In connection to the critical leap: you are quite meticulous in your stone progression. Did you miss the 8K "snow white"? Or was it just a few more strokes on the 10K? I hear people who hardly seem to be able to live without their snow white and people who couldn't care less.

Thanks again!