Thread: Scratch pattern pictures

I'd like to share a few pictures of the scratch pattern that different hones leave on a metal surface.

I produced the pictures in such manner to maximize comparability.
I have often witnessed that with the slightest variation in lighting direction, a surface can go from seemingly scratch-less to a miniature image of the Grand Canyon.
It really is important that the light source remains at a constant inclination and angle, in relation to the magnified bevel. The striations have to run in exactly the same direction for each mounted specimen. And the photographed surfaces need to be in the same horizontal plane.

After thinking a bit about it, I took an aluminium T-bar, and cut off some pieces of about 1 inch. I placed them on the hones resting stable on two points of contact. I honed each one of them 20 laps on a different hone. I used almost no pressure. Because of the aluminium being so soft, on the two points of contact a bevel developed very quickly. I devised a method to place them under the scope in such manner that one bevel ended up perfectly horizontal, which allows for a clean focus at 40X magnification. (see attached picture)

The tested hones were: A DMT-E (1200 grit), a Belgian Blue Whetstone, a pinkish coticule, a yellowish coticule, a cyanish coticule, and a vintage coticule. I don't reveal which picture corresponds to which hone yet, to allow you gentlemen to make some educated guesses

Bart.

Well Bart,

Interesting experiment. Using aluminium is a good idea.

Looking at the depth of the grooves, I would put the photo's in the following order.
B1...E1....A2......D1/F2....C1

B1 being the deepest looking groves.

B1 would be the 1200 grit. E1 the blue and as for the coticules, I have no idea, but I think I might send three of them back and ask for my money back.

I agree with all you say about the lighting. You can do anything with photography. What I do trust is that since you have seen the real grooves at all angles and in all lights, the order you give is factual whatever the pictures tell us.

But be careful though, if members find they have the wrong coloured coticule, it will be your responsibility if they are found sitting outside their backdoors crying a muttering obscenities under their breath.

Originally Posted by English

Well Bart,
But be careful though, if members find they have the wrong coloured coticule, it will be your responsibility if they are found sitting outside their backdoors crying a muttering obscenities under their breath.

B1 is a lightning fast coticule with a pinkish colour. I would have never guessed that one myself either. For absolute clarity: I used all hones with water only, no slurrys raised for this experiment.
I find the results very surprising: if they show us anything, it is that there's more to the coticules than the estimate of their grit-sizes. The way a scratch pattern looks under a scope does not tell everything about how the resulting edge feels to the skin and performs at cutting whiskers.
I consider all those coticules great hones, and I'm pretty sure their capabilities fall within the normal coticule limits. I've always been compelled to use Chromium Oxide after that pink one though, and I think I may have found out why, doing this experiment.

And yes, you got the vintage coticule right... I think. It looks a bit more out of focus than the other pictures, but actually it isn't. It looks the same when looking through the tubes of that scope as well.

Thanks for having a look.
Bart.

Once again a nice experiment, love your scientific and experimental approach towards honing.

Just some thoughts:
I've looked at the scratch pattern pictures but found it really hard to distinguish the different hones with the exception of the first pic being the DMT 1200 (but I could easily be wrong on this one).

Without wanting to be a pain in the ###, the scratch pattern and light contrast in the first picture is very noticeable and the others are not which is why it gives me the impression that the others are out of focus (again, I could easily be wrong).

Looking at the microscope photograph I assume it is not capable of digital imagery and had to shoot the pictures thru the eye piece.

You mentioned the consistent light angle on the subject, as for I can see the light source is attached (magic arm/ tripod?) and there for not able to move freely.
But I am wondering how you managed to achieve this with the aluminium object lying freely on the glass support of the microscope?

Due to your experiments with light you might find this interesting. Although the pics in the book are a bit old fashioned,
this is a very good, if not the best book on lighting principles there is:

Light: Science and Magic: An Introduction to Photographic Lighting

Maybe there is updated version available.

Joël,

E1 indeed is the DMT 1200. You got it right.

You're also right that my equipment and setup leaves a lot to be desired. That said, I do think that my pictures are consistent enough for them have at least some significance.
The light source is mounted on a swivel-type of attachment. I adjusted it for a shearing lighti angle, to maximize contrast in the scratch patterns. I placed all the specimen free hand on the base plated. Due to the shape of the T-bars, and the way they are resting on it, my honed surfaces end up parallel with the base plate, at a fixed height. Of course there are tolerances, and some of the specimen are a tiny bit more honed down than others, so I had to readjust the focal point of the scope for each specimen. That is something that can be done very precisely with any quality stereo microscope, and I'm sure there was no noteworthy difference in focus between the different samples. The weak link is that my scope lacks a picture tube, and that I shoot with a very generic digital camera (a Canon Digital Ixus V2). I left the camera's settings untouched for all shots and allowed the lens to rest against the hard plastic of one of the scope's eye pieces. I shot all of them twice. There was only very marginal difference between any of those two pictures.

I think it's no coincidence that the DMT looks better focused. What the pictures don't really show, as opposed to looking with both eyes through the tubes and seeing depth, is that the coticule scratches are way more shallow than the DMT pattern. It looks to me as if the coticule leaves very rounded scratches with soft corners, while the DMT leaves a far more harsh, "squared" scratch pattern. After all, the coticule's abrasive particles are little spheres. That makes the DMT's pattern more something like "uuuuuuuu" and the coticules more like "~~~~~~"
It's a pity that I couldn't throw in a DMT-EE (8000grit) or a Norton 8K into the experiment, it sure would be very interesting to do a professional version of this experiment on a larger test group of hones in a real lab with all the right equipment.

Best regards,
Bart.

I received a few samples of USB scopes at a trade show this past spring. This post has created an urge to do some scratch pattern comparisons. I've used the 'digital camera against the scope lens' method for too long .

For those gents who care to know, here 's the line up, ordered visually from coarsest to finest:

DMT 1200 (E1)
pinkish coticule (B1)
Belgian Blue Whetstone (F2)
cyanish coticule (D1)
yellow coticule (A2)
vintage coticule (C1)

Of course, the questions remains whether real life shaving tests would yield the same results.
To find out, I have set up another experiment:

8 identical Double Arrow razors will be divided in two groups of 4. I will hone group A and my straight shaving pall Kris will hone group B.

In both groups:

razor 1 will be honed on a DMT1200 only, till it passes our standardized version of the HHT (my youngest daughter was proud to donate a freshly washed strand of her thick, coarse hair for a just cause) It will be stropped 100 laps on clean leather

razor 2 will be honed, toe leading X-stroke, on a DMT 1200, till HHT positive, and next regular X-strokes on the BBW with water, till the underlying DMT pattern is completely wiped out (checked at 40X magnification, the toe leading X-stroke causes the underlying pattern to run in another direction, which makes it easier to see when the job is done)
It will be stropped 100 laps on clean leather.

razor 3 will be honed, toe leading X-stroke, on a DMT 1200, till HHT positive, and next regular X-strokes on the pinkish coticule with water, till the underlying DMT pattern is completely wiped out. It will be stropped 100 laps on clean leather.

razor 2 will be honed, toe leading X-stroke, on a DMT 1200, till HHT positive, and next regular X-strokes on the vintage coticule with water, till the underlying DMT pattern is completely wiped out. It will be stropped 100 laps on clean leather.

The razors will be labeled randomly and Kris and I will exchange groups, so that we won't know what we're shaving with. We'll use 2 razors during each test shave and fill out a performance data sheet (still under construction, but I'll post it for peer review here, before we 'll start using it). We will conduct 6 shaves in total, hence each razor gets to be used 3 times. Each razor will be stropped 20 on linen and 40 on leather before each shave. It will be dried and oiled afterwards.

After the last shave, we're gonna compare the date sheets and decide on the next round of experimental edges.

If you guys think we've missed something, please share. We're open for all suggestions.

Thanks for your attention,

Bart.

Bart,

This is a really interesting thread. Promise me you won't do more than a few strokes when you realize you're shaving with the 1200-grit edge...

I agree with what you're saying about the V-shaped grooves of the DMT vs. the rounded grooves left by the natural hones. I think that's why a coticule or escher edge is more comfortable than an edge from an artificial hone. There's also a connection between the shape of the abrasive particles and how easily a hone creates a wire edge--I can't proove it, but I know it.

Keep up the good work,
Josh

Originally Posted by JoshEarl

This is a really interesting thread. Promise me you won't do more than a few strokes when you realize you're shaving with the 1200-grit edge...

Let's just hope my face is able to tell the difference. I secretly hope that it shaves really bad. Otherwise I might be publicly crucified by a posse of fine-hone owners.

[quote=JoshEarl;232101 I agree with what you're saying about the V-shaped grooves of the DMT vs. the rounded grooves left by the natural hones. I think that's why a coticule or escher edge is more comfortable than an edge from an artificial hone. There's also a connection between the shape of the abrasive particles and how easily a hone creates a wire edge--I can't proove it, but I know it.

Keep up the good work,
Josh[/quote]

Thanks for the encouragement. You make a good point about the wire edge. Being a typical coticule honer, I actually never met such a wire edge, and I do check all my edges under magnification.

For the moment, I'm tuning those 8 Double Arrows, to make them ready for the experiment (softening the hard edges of the tang and tightening those sloppy scales a bit). They all came new from Stamps22 with a smiling edge. I wonder if I should remove the smile first. Not that I don't like a smiling edge, but I do think they are more prone to uneven honing than razors with a perfectly straight edge. When honing a smiling blade, I sometimes have to go back to the hones after a test shave, because the heel or the toe is not entirely up to my (high) standards. With a straight edge, I can practically hone a razor and know I get consistent results every single time. What do you think?

Bart.

I decided to go ahead and remove the smile on those Double Arrows. I took me almost a full day, and heavy backache the next day , but I now have 8 razors that are easily "honeable" in my drawer, all HHT-positive after the DMT 1200.

I've also put a razor-performance-sheet together, that we can use to compare the differently honed razors. I call upon anyone reading and caring about this experiment to review the document (see attachement). I would like this thing to be as solid as possible, before we start using it.

Thanks for your attention,

Bart.