Thread: Hones, Edges and Bevels under the Microscope

Here is some more stuff from under the scope. I hope you will find it useful. The more I play, the more I realize I have a lot to learn...

http://www.tzknives.com/razorhones.html

Thanks to Lynn, Rich and Charlie for all their help with this.

Tim Z.

Some quick thoughts...

First off, a big thanks for doing these studies.

Were the blades stropped after honing (other than the blades that were used on pastes)?

My assumption is that the bright line we're seeing is the light reflecting off the slightly bent fin, which is slightly curled because of the heat of the lamp. I could be wrong, but this line reminds me of what you see with the naked eye when you flex the fin with your fingernail while looking at the reflection of a point light source (sun or distant incandescent lamp), so I'm hoping that it's the same thing.

If so, then from this angle I think we're seeing a reasonably well-defined fin, though with a lot of detail lost because of the poor way CCD's handle oversaturation. Still, I'd be curious to see a photo like this after a shave.

It's interesting that you can see the polymer coating on the feather (the speckling). IMO This is also why the feather blade has a somewhat matte appearance (note the lack of specular highlights). And that's a pretty fine microbevel on that blade - I wonder how they did it.

It seems that one of the big things chrome oxide does is even out the depth of the fin, which makes me suspect that the the relative "roughness" we feel on a non-chrome-oxided blade is simply the longer parts of the fin popping and flexing as they go over our face. This is consistent with the guys that do mid-shave stropping, who seem to think that the blade starts feeling scratchy before they restrop.

From the depth cues, the only stones that honed through the original 8k hone marks were the spyderco and the .25 diamond. I'm actually surprised the swaty didn't do this - it seems faster than that (I'm not surprised by the edge in the photo though).

For a bit of perspective, human hair is generally in the range of 40-120 microns thick. So even the grooves from the 8k norton (3 micron) are terribly small even at this magnification.

More resolution or magnification would be really nice, but I don't know where we can get an electron scope for cheap

Tim,

Very cool stuff. The coticule edge doesn't look so hot from this angle, does it? Was that done with slurry or without?

Just goes to show that pictures give some data, but don't tell the whole story... Thanks for your work on this!

Josh

Good questions. I've updated some of the page info to give a better understanding of what I did.

Tim Z.

Ah, I see you taped the edge for the test pass. That changes my interpretation quite a bit. I was assuming the odd look as you got away from the edges were purely due to DOF issues, but knowing there's also a double bevel explains a lot. For one thing, there appears to be some evidence of what has been long suspected - the pasted edges seem slightly ovalled - this is especially evident comparing the 5 stroke chrome oxide photo vs the 10 stroke chrome oxide photo vs the base 8k photo. Edit: ARGH! never mind! of course the edge is ovalled - the spine is propped up!

I'm curious how the edges were lit? Some of the photos show keyholed lighting patterns and some show even lighting patterns. Was the light source fixed to the scope or was it a separately positioned source? It's possible that the reason some edges look rougher than others is simply because the lighting in those photos allowed us to see better.

Regardless, these photos give some insight into into possible explanations for what we have experienced ourselves during our shaves. Great work!

Tim,

Thanks for the notes on your methodology--great stuff.

To my eye, the best looking blades are the chromium oxide and Chinese 12K blades. My beard likes a coticule edge better than chromium oxide, though.

Josh

I think at the magnification we're looking at we're mostly seeing smoothness and not sharpness. Those chrome oxide edges may well be duller than the coticule and other fine stone edges. But they do look awfully smooooth.

It's a shame those blades aren't in a shave-capable package. I'd love to know how they shaved in practice, and see photos of them post-shave to see what has changed.

Keep 'em coming Tim as it's very interesting to see what is going on at the edge. Are you using polarized light? I'm wondering about the rainbows I'm seeing on the steel or is that a holographic or other some such effect?

Howard,

I'm currently making a polarizing filter for the light. The rainbows, esp. along the edge" are from overexposure messing with a cheap digital camera sensor.

Ivo,

I'll be at the convention with Will from Classic Shaving. I'll most likely bring the microscope and a few other toys to play with. Thanks for the idea.

Tim Z.

I spoke with Tony about the picture of the coticule edge on his latest set of images. I was wondering what that gunk was on the edge of the blade. He said his test probably used too many strokes and overhoned the razor and what we're seeing there is evidence of overhoning. He also said stropping would take it off and stropping was not part of his preparation protocol for those pictures.

Whew! Had me worried there for a minute. We know from collective experience that the coticules work well and the process is to hone on the coticule and then strop on natural leather. This would be be consistent with what we're seeing on Tony's photos.