Thread: About Blues and Yellows

After reading more carefully, I think I get it now. I think you are right Ben.

Bart's point about the yellow w/heavy slurry being a very fast cutter leaving a duller edge than the blue w/slurry may seem atypical, but it's exactly what JoshEarl found after months of experimentation last year.

Originally Posted by ArdennesCoticule

Bart, very useful post! I enjoyed reading it!

I'm going to add the following website to this topic : Zowada Custom Knives - Stone Surfaces

Hi-res pictures of the bevels and edges of razors made after honing on different types of whetstones.

Please don't forget to click on the links at the bottom of the page!!!

I don't think I've found a magnified pic of an edge that's been honed and then stropped. Know where I can find one? Or can you even tell the difference? Some of those edges look pretty smooth.

I like your systematic approach as well and have been doing these tests for several years. My conclusions are different and I'm trying to figure out why. One variable may be your slurry. I use the Belgian recommended "abrasive milk" meaning the slurry should be the consistency of milk. That's thicker than water. I use my coticule to finish hone my razor all the time and then strop and then shave with no problem. In no way, shape, or form is it "barely shaveable". Again, why? Perhaps your beard is way different than mine or perhaps your shaving cream is different. There are SO many variables.

My take on the garnet crystals is different as well. The crystals aren't round. They're rhombic dodecahedra which is the crystal shape that has the most possible points of any crystal shape. The points are pointed randomly throughout the surface. When the slurry is formed another quality of garnet comes into play - cleavage. Moreso than any other mineral used in abrasives, garnet points cleave off the crystal as it's hit by the steel or the slurry stone and they go into suspension in the slurry. When the points cleave off they have fresh jagged surfaces and that's why the blue stones hone so quickly - much faster than a Chinese or an Arkansas for instance.

As far as coticules producing a wavy surface on an edge. I've been looking at these things under magnification for years and have never seen that effect produced. My magnification tools include a video magnifier, a Bausch and Lomb stereo microscope, and one of those newer 200x ProScopes, plus an assortment of loupes, OptiVisors, and illuminated magnifiers. If you can send a pic of a wavy surface produced by a coticule, I'd love to see it.

Honing is a progressive process. It progresses from coarser to finer. The belgian blue is a 4000 grit stone. The yellow coticule is an 8000 grit coticule. Honing should progress from the blue to the yellow to the strop. Regardless of whether you're using water or a slurry, the particles on the blue are bigger and will yield a coarser edge in need of refinement. Neither of the coticule stones will hone an edge sharper than a Shapton 16k and certainly not a Shapton 30k!

This is a good discussion and I'm glad you're experimenting.

Originally Posted by Ben325e

He is neither saying to go from the blue to the coticule or from the coticule to the blue, at least not in such simple terms.

Combining (1) and (2) we get this:

(3) (Coticule w/ slurry) < (Belgian Blue w/ slurry) < (Coticule w/ water)

Bart, please don't feel like I'm trying to put words in your mouth, I was just trying to eliminate confusion. If I was wrong on any of these points, please feel free to correct me!

Ben, I was out hiking in the Ardens during the past few days. Thanks for stepping in for me.
Your exegesis is correct.

I like to think of hones in three categories:

1. Hones for bevel formation: DMT's 325 600 1200, Shapton 1K and 2K, Coticules with slurry,...

2. Hones for edge refinement: DMT 8000, Norton 4K, Shapton 4K and 8K, Belgian Blue with slurry,...

3. Hones for edge polishing: Chinese 12K, Shapton 16K and 30K, Nakayama, Coticule with water,..

Some of those hones probably could -with some extra effort- work in a lower category as well, I'm thinking about the Norton 4K and Shapton 4K for bevel setting purposes. And If I understand correctly, the Shapton 16K will still do more for the edge than merely polishing it and the Naniniwa Chosera 10K also seems to cut fast enough to do some actual refining, which means that those hones have the power to correct (to some extent) work neglected at the previous honing stage.

Bart.

Copied, reformatted, minimally rephrased, and now part of the Wiki: Coticule Hones - Straight Razor Place Wiki

Since there seems to be a certain amount of controversy, I would like to humbly suggest that someone review and, if necessary, amend this entry. All bases covered in this post if you need help with editing the Wiki: http://straightrazorpalace.com/rules...-srp-wiki.html

Originally Posted by Howard

I like your systematic approach as well and have been doing these tests for several years. My conclusions are different and I'm trying to figure out why. One variable may be your slurry. I use the Belgian recommended "abrasive milk" meaning the slurry should be the consistency of milk. That's thicker than water. I use my coticule to finish hone my razor all the time and then strop and then shave with no problem. In no way, shape, or form is it "barely shaveable". Again, why? Perhaps your beard is way different than mine or perhaps your shaving cream is different. There are SO many variables.

Thanks for sharing your experience on this thread, Howard. It's much appreciated.
It's true that I never got a great edge right off a coticule with slurry, regardless how thick or thin I make it, with the one exception that gradually diluting the slurry while honing produces keener edges.
Am I understanding correctly that you finish on a Coticule with slurry, and get great edges out of that? Our beards and/or our Coticules must be very different in that case.
But even so, I have witnessed what I reported with many different Coticules. I have performed as little as 10 back and forth strokes on razors that shaved very well, and afterwards shaved much less well. I have done double blind tests on 8 identical razors, honed in pairs. All of them honed till they passed the HHT coming off a DMT D6E. Then, 2 of them 50 laps on a Blue with slurry, 2 of them 50 laps on a Coticule with slurry, 2 of them on another coticule with slurry, and the two last ones on yet another coticules. All 3 coticules were known to be good finishers when used with water. I honed 4 of them, and my "brother in arms" Kris honed the other 4. We swapped the groups and test shaved them in a carefully devised test sequence. (we're conducting those kind of tests for over 4 months now - parts of it are in this thread: http://straightrazorpalace.com/advan...-pictures.html) Sometimes we quit shaving tests for reasons that the edges really don't shave well, and we're not in this for torturing ourselves. In case of the coticule slurry edges we stopped rather soon, concluding that the Blue/slurry finished edges were keener than the Coticule/slurry edges. In another test, we compared bare Blue-with-slurry egdes against edges that received an additional 100 laps on coticules with water. The blind tests revealed the coticule/water finished edges as better shavers than the blue/slurry finished ones.
Furthermore, I gather up with 4 straight shaving friends regularly, for joined honing and shaving sessions. We all seem to have similar experiences when it comes to the effects of finishing on slurry.
I'm not writing this to dissmiss your different expierences as insignificant. I merely like to point out that I didn't draw my conclusions solely on my personal results with the Belgian hones.
It puzzles me that you (Howard) have other experiences. It surely demonstrates that for the aspiring honer personal experiments must be encouraged. Nevertheless, for someone starting out on the Belgian hones, I'd still recommend getting a good bevel on a DMT1200 or some other hone up to that task, progress to a Blue with slurry and finish on a coticule with water. I think that offers the best shot at consistent results.

Maybe now's also a good time to point out that if anyone's willing to go to a pasted strop after the use of a coticule with slurry, none of the above matters. But I always found my edges to not last very long every time I went to a pasted strop (without running any further testing, that strictly remains a personal observation), so I hardly ever use pastes anymore.

Originally Posted by Howard

My take on the garnet crystals is different as well. The crystals aren't round. They're rhombic dodecahedra which is the crystal shape that has the most possible points of any crystal shape. The points are pointed randomly throughout the surface. When the slurry is formed another quality of garnet comes into play - cleavage. Moreso than any other mineral used in abrasives, garnet points cleave off the crystal as it's hit by the steel or the slurry stone and they go into suspension in the slurry. When the points cleave off they have fresh jagged surfaces and that's why the blue stones hone so quickly - much faster than a Chinese or an Arkansas for instance.

I am aware of the "rhombic dodecahedra" shape (thank god, for copy and paste hotkeys in Windows). But, if I was informed correctly, they're round enough to spin underneath the steel, and also round enough to create curved scratches.
About garnet cleavage, all sources I know of report that spessartine garnets show no cleavage. Garnet - Wikipedia, the free encyclopedia and » Spessartine Garnet among a few others.
They can be fractured, but I think this is unlikely to happen from light pressured honing forces.

Originally Posted by Howard

As far as coticules producing a wavy surface on an edge. I've been looking at these things under magnification for years and have never seen that effect produced. My magnification tools include a video magnifier, a Bausch and Lomb stereo microscope, and one of those newer 200x ProScopes, plus an assortment of loupes, OptiVisors, and illuminated magnifiers. If you can send a pic of a wavy surface produced by a coticule, I'd love to see it.

I use a high end Nikon stereo microscope, but unfortunately such devices lack the optical resolution and depth of view to catch the physical appearance of the scratches. My hypothesis about the shape of the scratch pattern is based on the shape of the garnets and on a simulation with 3D modelling software, called Minos. Unfortunately, I'm a complete noob with this program and I am yet to figure out how I can export the drawing outside my trial version. I was planning on posting that in a future thread. But still, it's a hypothesis and I can't back it up with physical evidence. That's why I started that paragraph of my initial post with the word "controversial".

Originally Posted by Howard

Honing is a progressive process. It progresses from coarser to finer. The belgian blue is a 4000 grit stone. The yellow coticule is an 8000 grit coticule. Honing should progress from the blue to the yellow to the strop. Regardless of whether you're using water or a slurry, the particles on the blue are bigger and will yield a coarser edge in need of refinement. Neither of the coticule stones will hone an edge sharper than a Shapton 16k and certainly not a Shapton 30k!

Maurice Celis told me in an e-mail, that Coticules have a garnet size of 5 to 15 micron and Blues
a size of 10 to 20 micron. In my logic the size of the garnets defines the scratch pattern of a hone. According the DMT website, their DMT-E (1200) has a particle size of 9 micron and the DMT-EE (8K) has a particle size of 3 micron. Where does that leave the Belgian hones?
Imo, it doesn't matter for the scratch pattern how much honing particles per square inch a surface contains, it's their size that matters. Because of that, lining up hones from different brands is never just a matter of lining up the declared grit or mesh ratings.
Apart from all that, in theory, the steeper a cutting bevel, the more the depth of the scratches becomes exagerated, which could easily be a more important factor in the resulting edge than the actual width of the scratches. This might also be the key to why some hones are prone to produce a wire edge.

Originally Posted by Howard

This is a good discussion and I'm glad you're experimenting.

I'm glad to have some one with vast experience looking over my shoulder.

Best regards,
Bart.

I've only been honing for about four months, but I use a yellow coticule as my finishing stone all the time (with slurry, water and sometimes with lather, and once in a blue moon with a few strokes dry). After finishing on a yellow it shaves me great. In fact, I haven't touched my chrome oxide or any of my other pastes since buying a yellow coticule - I go straight from there to strop and I love the shave and it's very smooth.

my other finishing stone is a yellow green escher which I also go straight to strop from, and love that too.

With ebay razors I go shapton 1k, blue wet, yellow slurry/wet/lather, or I replace the yellow iwth the yellow green escher. And I've been ecstatic with the results.

Incidentally I bought my blue and yellow coticule and yellow green escher from Howard, so they are good stuff.

Same here. I got my combo from Howard and it's an excellent performer.
I mostly use my blue with lots of slurry, continue until it's diluted and a few final laps with just plain water. Second the yellow, sometimes with a milky slurry or without. Again continue until diluted if used with slurry, wipe off and plain water for the final polishing
I can see the slurry or plain water turn grayish from all the steel removal and polishing. Never a problem shaving straight from my yellow. Always extremely smooth and sharp.
There seems to be a lot of quality performance between those natural stones but Howard just knows how to choose the right ones.

I agree i use thesame progression and i get exallant shaves i love the bbw and yellow progression and i have a tough beard