Thread: Same edge, same spot, same magnification, different light...

He just wants to illustrate that pictures have their own peculiar way of telling a truth.

Originally Posted by hi_bud_gl

First sentences how he started his threat and second one how he did explain ?
at first "different light "
next "same light"
what he was trying to do ????
confuse us or to get help from us?

I'm sorry Hi_bud, never meant to confuse you.
I've should have titled it "different light conditions".
Indeed I was trying to make a point that pictures at magnification can be very ambiguous.
The same edge may look completely smooth or deeply scratched. All it takes is a minor adjustment of the lightng angle.
Actually I saw a thread last night were someone posted scratch patterns left by two different hones. I noticed how he placed the razors at a different angle under his scope (which has the same effect as altering the lighting angle). I wanted to illustrate how easy it is to jump wrong conclusions out of that, but decided to start a new thread, rather than offense someone that I respect, and know to have only good intentions with sharing those pictures.

My apologies for the confusion,
Bart.

for clarification.I was just a little confused and trust me i don't have any hard feeling.thank you for a nice pictures it help .if you could compare 50x, 100x to 200x same blade in exact condition i would appreciate.on y microscope i can see only 50 aND 100x,300 doesn;t help much.
thank you

Originally Posted by Bart

Yes, it's an edge with a secondary bevel. I've been experimenting with it quite a bit lately. I think it's great for comparing the capabilities of various hones, because the very edge is only formed by the last hone in the progression. (There's lot to be said about this topic, but a bit besides the scope of this thread)

That was my point exactly. The angle of the light hitting the subject makes tremendous difference, even within very few degrees of variation. All pictures are lit by the same light source, only with slightly different angles. The razor itself was not touched. Magnification is 50X, by the way.

For those who wonder, the scratches running in opposite directions on the second picture, are actually very shallow strop marks.

Bart.

Very dramatic difference between the first picture and the last.

I'm sorry if this question falls into the "outside of the scope of this thread" realm, but without getting too deep into it.. Just wondering if you're creating the secondary bevel angle by putting two layers of tape on the spine? That's all I'll ask.. promise.

Hi All

Realise its a while since my last post, but I thought I can add something useful to this.

I use a small handheld microscpoe with a built in light source to see how things are going during honing - the every popuar tandy style of thing. It is exactly for the reasons above that I set the focus on maximum and hold the edge of the razor below the base of the 'scope. This way I can angle the blade and get the light reflecting off the edge in several different directions, thus seeing the "whole picture".

It requres a steady hand, but I find it really helps to get an overall impression of the bevel edge along its entire length.

Sunsi

Bart, I never realized how dramatic the differences could be under differing angles of lighting, or differing blade angles for that matter. This will make me view what I see under the microscope in a whole different light.

Originally Posted by JCitron

...a whole different light.

J, your dark side is brilliant!

Originally Posted by FloorPizza

Very dramatic difference between the first picture and the last.

I'm sorry if this question falls into the "outside of the scope of this thread" realm, but without getting too deep into it.. Just wondering if you're creating the secondary bevel angle by putting two layers of tape on the spine? That's all I'll ask.. promise.

The razor was honed with the following progression:

(Without taping the spine)
DMT 1200 (till it popped hairs)
Naniwa Chosera 5K (till the TPT-feeling maxed out after about 20 laps)
Naniwa Chosera 10K (20 laps)
Nakayama (40 laps)

At this point I test shaved. The razor was rated 21/30 on my personal razor performance sheet. (I've attached a PDF-version, the first column contains the detailed score)

That's certainly within the domain of shavereadiness, but I wondered if I could do better.
Two days later, I added two layers of tape to the spine, did 8 laps on the Chosera 10K. This created the secondary bevel. After that I did 30 light laps on the Nakayama, which did not noticeably widened the seconday bevel. I removed the tape, stropped and went to business.
The results are in the second column. I had a sightly better shave. I always have better shaves with putting a secondary bevel on that Dovo. I don't know why. It's not the same with all my razors: some benefit from a secondary bevel and others don't. Even more puzzling is the fact that it really differs how I make that bevel. I could have produced the same secondary bevel with only using the Nakayama. (It's a bit like sanding down a hard wooden edge, the first strokes are the most productive, with the broadening of the bevel the action slows down exponentially) But the resulting edge would have performed differently. Some hones seem to be really excellent for polishing, and others for refining.

Now you know why I stated there's a lot to be said about this topic.
I'm only at the verge of this. (yes Mr. Citron, me likes wordplay too)

Bart.

Bart, the gem here is your razor performance chart! I love it. I'll say that I think it should be a standard! Thank you for that.

I'm also pleased to see the rating #5 under Keenness "Hair breaks and falls silently" is EXACTLY what I've mentioned regarding my findings in levels of HHT and that IME a hair that responds in that manner has repeatedly yielded my sharpest edges.

So......HA!! That's two of us that have found this to be true. The shave test is the pinnacle test; however, the HHT IMO is NOT a parlor trick.

One question for you. I don't do double bevels on razors or at least I have not yet. From what I've read and what I've done personally with chisels and micro/double bevels, IME it takes only a few strokes to establish an effective double bevel. Literally a few. What do you find if you do only 5-10 or fewer passes when establishing a double bevel?

The following is NOT a criticism; when I first saw your photos and spotted what I thought was a double bevel I thought the secondary bevel seemed to be large. I'd like to hear your thoughts on the number of passes for the secondary bevels and what you've found the least number of strokes you've done, etc.

Thanks again for the chart. Just wonderful.

Chris L

Originally Posted by Chris L

Bart, the gem here is your razor performance chart! I love it. I'll say that I think it should be a standard! Thank you for that.

You're welcome. After some serious pondering, that's what I came up with to keep track of the "double blind test"-results, but I find myself using it for assessing the results of unblinded honing experiments as well. Without saying that it should be mine, I agree that a standardized method for rating razor performance could be a meaningful addition to many conversations about honing.

Originally Posted by Chris L

I'm also pleased to see the rating #5 under Keenness "Hair breaks and falls silently" is EXACTLY what I've mentioned regarding my findings in levels of HHT and that IME a hair that responds in that manner has repeatedly yielded my sharpest edges.
So......HA!! That's two of us that have found this to be true. The shave test is the pinnacle test; however, the HHT IMO is NOT a parlor trick.

I couldn't agree more. For me, from all the predictive tests, the HHT comes closest to tell what I can expect during actual shaving.

Originally Posted by Chris L

One question for you. I don't do double bevels on razors or at least I have not yet. From what I've read and what I've done personally with chisels and micro/double bevels, IME it takes only a few strokes to establish an effective double bevel. Literally a few. What do you find if you do only 5-10 or fewer passes when establishing a double bevel?

I agree. The creation of a secondary bevel takes only very few laps.
BUT... (there's always a "but", isn't there?)

I 've come to think of honing in two different actions:
There's the action of refining. Making the point of the V thinner, sharper.
And there's the action of polishing. Removing the peaks of the scratch pattern on the surface of the V. At the same time this cleans up the meeting line of both bevel panes of our "V".

Some hones I qualify as both polishers and refiners. Once they 've hit the bottom of the previous scratch pattern, they just continue to emboss their own scratch pattern, hence refining the "V". They always max out at either a certain keenness level or a wire edge, depending on the hone itself.

Other hones I qualify as polishers only. They eat their way through a given scratch pattern, but one they approach the bottom of the pattern, they become too slow for any further "V" refinement. This is directly related to the decreasing PSI, as the contact surface enlarges. For that same reason, even a polishing hone can refine an edge when a few layers of tape divert all abrasive force to an extremely small part of the edge.

In practice with coticules, all this theory translates into the following (please bear with me, I assure you this is leading somewhere)

A coticule with slurry is a refiner, but, as we all know, it maxes out at an early level of shavereadiness.

A coticule with water is a polisher, one of the very best ever, but one without hardly any refining capabilities, hence the need for an already very keen edge.

I you force a coticule with water into a refiner, by using the secondary bevel trick ("diverting all abrasive action to an extremely small part of the edge"), it will refine the edge, BUT (here's the actual "but") at the same time this also introduces the maxing out issues of the coticule with slurry. Not entirely to the same extent, but still. The bottom line is that coticules have qualities as a polisher beyond the maximum sharpness you can squeeze of out a bare coticule induced edge.

For my experiment on the Dovo, I was not after the refining qualities of my Nakayama. (They yield about the same results as s secondary bevel, produced by my coticules). I used the Chosera 10K as a refiner and once the secondary bevel was wide enough, the Nakayama as a finisher.
On the Dovo, the final results gave me an easier shave than the same progression without the formation of a secondary bevel. (As stated before, my Dovo is notorious for that). The razor really went through the whiskers with less effort, most noticeably during the ATG pass.
If I was after testing a secondary bevel left by the Chosera, I would have stopped with 2 laps.

Let's just hope this still makes sense to you.

Best regards,
Bart.