polishing: blade geometry

[KenjiF]

The black stuff your seeing is the material that’s coming off your blade (swarf) mixing with the mud created from the stone. The blacker it is the more swarf to mud generally. IME some of my stones will clog with the swarf. The stone will start slowing down as the surface gets smoother and less abrasive (mud) is being released. If you want the stone to cut then refresh the stone with atoma or nagura. If you want to burnish the clogged stone will actually make it easier to achieve that as the surface is glassy and smooth.

I’ve heard people say when sharpening not to refresh the stone because it acts finer as the stone clogs but I’m not sure if that’s true. I can see some advantages to a burnished edge but burnished doesn’t necessarily mean sharp.

 

[M1k3]

The black stuff your seeing is the material that’s coming off your blade (swarf) mixing with the mud created from the stone. The blacker it is the more swarf to mud generally. IME some of my stones will clog with the swarf. The stone will start slowing down as the surface gets smoother and less abrasive (mud) is being released. If you want the stone to cut then refresh the stone with atoma or nagura. If you want to burnish the clogged stone will actually make it easier to achieve that as the surface is glassy and smooth.

I’ve heard people say when sharpening not to refresh the stone because it acts finer as the stone clogs but I’m not sure if that’s true. I can see some advantages to a burnished edge but burnished doesn’t necessarily mean sharp.

My experience with 1 super clogged India fine stone says, yes, it acts finer. With the caveat of stray scratches that aren't extreme.

Take that as you will, it's just 1 singular example.

 

[noj]

The black stuff your seeing is the material that’s coming off your blade (swarf) mixing with the mud created from the stone. The blacker it is the more swarf to mud generally. IME some of my stones will clog with the swarf. The stone will start slowing down as the surface gets smoother and less abrasive (mud) is being released. If you want the stone to cut then refresh the stone with atoma or nagura. If you want to burnish the clogged stone will actually make it easier to achieve that as the surface is glassy and smooth.

I’ve heard people say when sharpening not to refresh the stone because it acts finer as the stone clogs but I’m not sure if that’s true. I can see some advantages to a burnished edge but burnished doesn’t necessarily mean sharp.

Sounds mostly as I thought. For showing high spots, I will try without removing any black clogging, as long as the stone stays flat and clean. The thing that puzzles me still is why the burnishing configuration leaves my cladding so dark, vs shiny/polished. Maybe those are low spots?

 

[KenjiF]

Dark is low. As I said earlier it was hard to burnish the full bevel on my togashi on 3k stone. The highs would get burnished but as the geometry got better and more of the bevel was touching the stone everything went dark. This will just take some experience but it’s almost always better IMO to drop back down grit to grind down the highs and keep checking on the 3k to make sure you got them . Grinding any meaningful amount of material at 3k is miserable. Anything over 1k I’d consider a stone to check geometry or to remove the previous grit scratches. How low down you have to go is just experience seeing how big a low you have and what grit is going to be most efficient for removing it (and the time it will take you to delete the scratches that grit makes). 90% of the time I spend on stones if I’m fixing geometry will be spent under 400 grit.

 

[KenjiF]

Burnishing configuration would be generally… hard stone, glassed over (smooth surface), no or little mud, lots of water and higher pressure.

 

[noj]

Here's pictures after 3k Chosera. The stone did not want to glass over, and there was a lot of mud. The pressure was placed in the middle of the cladding only.

The cladding mostly got dark. I can't tell if several shiny spots are due to height, or simply missed the stone. For example, near the tip (last 5-10 mm) where I previously ground off a high spot, and now looks convex and narrower. For example (maybe, can't tell), along the shinogi, where I probably over-ground, and avoided putting pressure for this exercise. Guessing magic marker time;-)

I still suspect a high spot near the tip because of the large rougher spot below it, most visible on RHS.

Also maybe near the handle at the shinogi (hard spot to get to)

Here's another view of the shiny area along the shinogi that I am guessing isn't high .

I also have pics of LHS, but let me see what feedback I get.

As far as a stone that might burnish, I have a Super Stone, but it's not hard, and it warps when wet. Maybe a flat, clean, un-clogged stone would show high spots as bright scratches in the now dark cladding (vs polish) instead?

PS: The wood in the pics is a paint stick because I had the blade lightly clamped to the cutting board.

 

[KenjiF]

@noj that looks pretty damn good to me. I agree that the shiny spots at the shinogi are not highs but lows. Looks like coarser scratches up there so I would say you hit those areas with a softer coarser stone but aren’t able to reach them with the 3k.

To fix this you want to focus on grinding the high spots on either side of the low. I’d drop back to around 1k first to see if that is enough to remove the material needed. It’s super common and still something I do if I’m not paying attention. Put your finger pressure just below the shinogi right on the high you are targeting. Take it slow at first and be careful not to twist over the shinogi. It can help to lessen the pressure on the pull stroke and increase on the push stroke. The pull stroke is where I’m most likely to roll over the shinogi.

Put it back on the 3k intermittently to check you have removed enough material.

I like super stones and my 5k does burnish but it feel softer to me.
Great work!!

 

[mengwong]

Nice work! Your session went better than mine – this supposedly double-bevel knife has a left face that is all low spots, basically an urasuki, sigh. After an hour on stones I gave up and switched to sandpaper sponge, 400, 1500, 6000. Surprisingly smooth though some pitting is still visible.

 

[noj]

@noj that looks pretty damn good to me. I agree that the shiny spots at the shinogi are not highs but lows. Looks like coarser scratches up there so I would say you hit those areas with a softer coarser stone but aren’t able to reach them with the 3k.

To fix this you want to focus on grinding the high spots on either side of the low. I’d drop back to around 1k first to see if that is enough to remove the material needed. It’s super common and still something I do if I’m not paying attention. Put your finger pressure just below the shinogi right on the high you are targeting. Take it slow at first and be careful not to twist over the shinogi. It can help to lessen the pressure on the pull stroke and increase on the push stroke. The pull stroke is where I’m most likely to roll over the shinogi.

Put it back on the 3k intermittently to check you have removed enough material.

I like super stones and my 5k does burnish but it feel softer to me.
Great work!!

I am still working on it as I have time.

I verified with magic marker that the shiny area at the "tip" is low. The magic marker effects are harder to see along the shinogi, but the course scratches pretty much confirm it isn't a high spot.

When the knife was new (as were my sharpening skills) I spent many hours abusing it to get rid of all the low spots. I have been mostly staying away from the shinogi since then. I may come back to it later.

Things are looking better. There are still remnants of something from pic #1 above. That photo doesn't know it well, and looks different as I work on it. Will post more if I get a handle on it. I did notice after using a shapton 1000, I felt I got a lot of information on the geometry by looking at reflections in the scratch marks. Maybe a lot more detailed information that looking for burnishing marks. The funky spot looked like a 5mm convex (likely high) spot right next to a 5 mm (likely low) spot - based on reflections. I think I got rid of it with the shapton 1000. Another observation: at some level of refinement, sharpie ink becomes too thick to be useful.

I am sure the answer will be "it depends", but I wonder how you and others deal with the heavily darkened cladding in a polishing progression. Specifically, do you ever get rid of it at one/some point(s), or just modify with different stones and technique? I tried polishing a mono-steel (polished) on stones, and had to spend a lot of time cleaning/flattening the stone. I am not likely to want that effect (mirror-ish) on the cladding. I am just trying to understand the process more. I am not sure I have seen any videos where the cladding gets as dark as I have it, though it could just be the lighting.

 

[KenjiF]

I’m usually aiming for dark cladding. Kasumi is cloudy or foggy looking cladding and it’s usually desired to have as much contrast as possible between the iron and steel. As you get finer the cladding will generally get lighter. If you want a mirror finish on the cladding a sandpaper progression or buffing wheel is probably the easiest way to achieve it.

 

[noj]

Well, here's my stopping point on this for the moment; but, not because I gave up. I tried a bunch of stones, and I can get some contrast to see details in the stainless cladding. The details are so small, and contrast light, I can't photograph it. I think I got the best contrast on a finer finishing stone, but also brought out some unevenness - no surprise.

There is a broad and shallow low spot toward the center of the RHS. It's where the shinogi dips toward the edge, as you might guess. There's a lot of exposed cladding on the RHS already, and very TBE, so I am inclined (edit - NOT) to grind more at this time. I did try and check for bending, or corresponding high spot on the other side, and see neither. Since it's next job is the kitchen, I thought it might work better with a courser finish, so I attempted this on an Aizu. Pictures below.

I have to try polishing some non stainless next.

 

[KenjiF]

Looks great. Nice work!

 

[noj]

More questions. One observation I made is the appearance of darker and scratchier spots where the cladding line dips toward the edge. Pictures below (two different blades). It makes sense to me that the cladding line dips due to a low spot, or at least a lower spot in the core steel.

Does/did this happen to you, and how do you fix it? How hard does one work to remove these? Should I work remove these? What part is knife geometry vs polishing technique?

One guess is that the appearance of scratches is an actual low spot, and would be nice to remove. I might be running out of remaining steel near the edge, in which case I'd prefer to leave it alone at least until it naturally wears from kitchen use.

The more subtle dark spots where the cladding line dips toward the edge might be a lower spot in the core steel. Maybe it's dark due to mud etching that area more.

Related or not, one area I find difficult is thinning the core steel, especially using finger pressure alone. Maybe by the time I make progress on the core steel, mud has etched a low spot right behind it?

 

[ethompson]

You're seeing very subtle low spots. Either they got missed as you worked up through the grits and now the particles are fine enough that the slurry won't polish those areas or, equally likely, your blade has moved as you've been working it and altering the balance of tension between core and clad. Check the edge straightness. I've also had a knife move to one side... When doing this much grinding on a blade, they will move in subtle ways.

If you're working on a major project the first, second, and fourth thing you should do every time you pick the blade up is check the straightness at the edge and the evenness of the bevel.

I recently worked on a hinoura santoku that had hollow bevels. In one long session I evened both be bevels and put a nice stone finished polish on the right hand side. A week later I picked it back up and the right bevel was subtly hollow again. Had to rework the whole bevel to take it back to convex.

 

[noj]

You're seeing very subtle low spots. Either they got missed as you worked up through the grits and now the particles are fine enough that the slurry won't polish those areas or, equally likely, your blade has moved as you've been working it and altering the balance of tension between core and clad. Check the edge straightness. I've also had a knife move to one side... When doing this much grinding on a blade, they will move in subtle ways.

If you're working on a major project the first, second, and fourth thing you should do every time you pick the blade up is check the straightness at the edge and the evenness of the bevel.

I recently worked on a hinoura santoku that had hollow bevels. In one long session I evened both be bevels and put a nice stone finished polish on the right hand side. A week later I picked it back up and the right bevel was subtly hollow again. Had to rework the whole bevel to take it back to convex.

Thanks for the suggestions.

I have tried many many times, with the suggestions on this thread, but I am not sure if I can detect anything but the most gross bends. I am using one eye open, and using a led light with white printer paper over the front (of a trouble light) for background. The only knife I have where I can see bending is a cheap flexible utility knife I inherited from grandma, and even there I can only see a bent spine. Looking down the edge, I can't see much of anything on this or any knife.

I am at a loss as to anything being missed per se. I have worked through grits maybe 10's of times, and get the same result.

 

[refcast]

Ahh then maybe I can be of assistance.

The mud while thinning the core steel, it does darken the iron right behind it if the mud is pressed on it, or rolled across it. It's how darker kasumi is made with loose grit.

You can wash the stone more frequently to reduce mud build up, but that's what it is. When the stone contacts the iron cleanly, then I would get brighter iron. When the stone or mud contacts the iron with light force, then I would get darker more matte iron.

To only polish core steel, you can try using sharpening strokes parallel to the edge, this should help reduce contact with the iron darkening too.

 

[noj]

Ahh then maybe I can be of assistance.

The mud while thinning the core steel, it does darken the iron right behind it if the mud is pressed on it, or rolled across it. It's how darker kasumi is made with loose grit.

You can wash the stone more frequently to reduce mud build up, but that's what it is. When the stone contacts the iron cleanly, then I would get brighter iron. When the stone or mud contacts the iron with light force, then I would get darker more matte iron.

To only polish core steel, you can try using sharpening strokes parallel to the edge, this should help reduce contact with the iron darkening too.

Thanks for more ideas .. for the problem at hand, and general concepts.

I think I see this after trying to go through stone progressions on the cladding. I don't think it's introduced when working the core steel, but I will keep your idea in my bag of tricks.

 

[KenjiF]

Hey @noj,
Sounds like a slight low as @ethopmson said. Pretty common for me when I move from higher pressure (either burnishing or aggressively thinning or just being stubborn and rushing). It usually happens in the middle of the knife and what I’ve done is put pressure on the handle and the tip with the middle of the blade off the stone and bent the knife a slight bit as I’ve been polishing. On a very thin knife it’s super easy to do. You might only notice on a harder stone as the softer one can still reach the low spot. Also make sure it’s not the light that is tricking you. Under harsh ‘hard light’ you will see lots of detail (scratches) at the point that light is bouncing off the blade and less detail where the light isn’t hitting.

Hard light is light that is a small source compared to the object you’re looking at. If you think of the direct light from the sun on a cloudless day it will be a very small light source. If you look at someone’s face you will see lots of detail and crisp lines between shadow and highlights. This is hard light. If it’s a cloudy day then then the clouds are diffusing the light and the light source becomes the whole sky. Shadows will be much softer and blend together (less contrast and detail). This is soft light. It will generally make something like a Kasumi finish much more pleasing and even looking… when people say ‘afternoon light Kasumi appreciation’ this is what they are talking about in terms of the quality of light.

In your example the light source is reflected in the shot from above and it’s hard. That will mean that the point it’s reflecting from will show more detail and scratches. Where the light is not directly reflecting from it is lit by the light bouncing around the room and that light is much softer and you won’t see the details.

To make sure this is not the case tilt the blade and make sure you’re not seeing the same scratch pattern as you bring different parts into direct contact with the light source.

I keep meaning to do a video on lighting for knives to explain it correctly. Just make sure it’s an actual low and not a ‘trick of the light’ before you thin.

For straightening it just takes some time to train your eyes. Make sure the knife isn’t too close to your face as your eyes have a minimum distance they can actually focus( thats why your nose is blurry right now). For me it’s at least 8 inches but will vary between people. You are training your eyes to be able to gradually shift focus down the blade road. That is not something your eyes are used to so it will just take some practice and you will get more and more accurate the more you do it.

There must be another way to do it. Maybe a laser level . I still miss small bends especially on thin knives. Between what the stone is telling me and my eye I’ll figure it out eventually but it can be frustrating.

 

[noj]

Hey @noj,
Sounds like a slight low as @ethopmson said. Pretty common for me when I move from higher pressure (either burnishing or aggressively thinning or just being stubborn and rushing). It usually happens in the middle of the knife and what I’ve done is put pressure on the handle and the tip with the middle of the blade off the stone and bent the knife a slight bit as I’ve been polishing. On a very thin knife it’s super easy to do. You might only notice on a harder stone as the softer one can still reach the low spot. Also make sure it’s not the light that is tricking you. Under harsh ‘hard light’ you will see lots of detail (scratches) at the point that light is bouncing off the blade and less detail where the light isn’t hitting.

Hard light is light that is a small source compared to the object you’re looking at. If you think of the direct light from the sun on a cloudless day it will be a very small light source. If you look at someone’s face you will see lots of detail and crisp lines between shadow and highlights. This is hard light. If it’s a cloudy day then then the clouds are diffusing the light and the light source becomes the whole sky. Shadows will be much softer and blend together (less contrast and detail). This is soft light. It will generally make something like a Kasumi finish much more pleasing and even looking… when people say ‘afternoon light Kasumi appreciation’ this is what they are talking about in terms of the quality of light.

In your example the light source is reflected in the shot from above and it’s hard. That will mean that the point it’s reflecting from will show more detail and scratches. Where the light is not directly reflecting from it is lit by the light bouncing around the room and that light is much softer and you won’t see the details.

To make sure this is not the case tilt the blade and make sure you’re not seeing the same scratch pattern as you bring different parts into direct contact with the light source.

I keep meaning to do a video on lighting for knives to explain it correctly. Just make sure it’s an actual low and not a ‘trick of the light’ before you thin.

For straightening it just takes some time to train your eyes. Make sure the knife isn’t too close to your face as your eyes have a minimum distance they can actually focus( thats why your nose is blurry right now). For me it’s at least 8 inches but will vary between people. You are training your eyes to be able to gradually shift focus down the blade road. That is not something your eyes are used to so it will just take some practice and you will get more and more accurate the more you do it.

There must be another way to do it. Maybe a laser level . I still miss small bends especially on thin knives. Between what the stone is telling me and my eye I’ll figure it out eventually but it can be frustrating.

Thanks for that detailed write up. On the topic of straightening, I am still unclear on exactly what I need to look at, and look for. In the Carter video, I think he looks just at the spine, and single eye (for non-propeller bending). That I can do because it's something I can focus my eye on. I can't find any issues with my good knives, but I can see lots of issues with my junky utility knife. If I look edge on, I can't focus, and things disappear into the background, so I am guessing this isn't the way.

For propeller bending, he uses both eyes, and looks edge edge on. I haven't tried this test yet.

 

[noj]

Well, for the straightening part, I am not yet able to get much from these techniques.

One thing I have tried, when the face is sufficiently reflective, is moving a deflection (in my case a circular light fixture) from heel to tip, and observing any anomalies. If the circle narrows (along the axis of heel to tip), it's concave, and widens convex. There's usually going to be some gentle convexity near the tip because of the shape of the blade. A concave spot in the middle would be unexpected, and a bend might be confirmed with a convexity on the opposite side.

And then there's my Nakiri. Right where I was having the worst trouble, one side and middle of the blade, I can see the face is concave. This corresponds to a huge low spot in the shinogi, further confirming a low spot. Oddly, I see the same thing on the opposite side, though it looks like I ground out that low spot on the bevel. In any case, I don't have evidence it's bent. The smaller dark/scratchier spots in the natural waviness of the cladding like, I am guessing is just technique.

I did look at all of this in hard and soft lighting. It's harder to see in soft lighting, but there nonetheless.

 

[noj]

Hey @noj,
Sounds like a slight low as @ethopmson said. Pretty common for me when I move from higher pressure (either burnishing or aggressively thinning or just being stubborn and rushing). It usually happens in the middle of the knife and what I’ve done is put pressure on the handle and the tip with the middle of the blade off the stone and bent the knife a slight bit as I’ve been polishing. On a very thin knife it’s super easy to do. You might only notice on a harder stone as the softer one can still reach the low spot. Also make sure it’s not the light that is tricking you. Under harsh ‘hard light’ you will see lots of detail (scratches) at the point that light is bouncing off the blade and less detail where the light isn’t hitting.

Hard light is light that is a small source compared to the object you’re looking at. If you think of the direct light from the sun on a cloudless day it will be a very small light source. If you look at someone’s face you will see lots of detail and crisp lines between shadow and highlights. This is hard light. If it’s a cloudy day then then the clouds are diffusing the light and the light source becomes the whole sky. Shadows will be much softer and blend together (less contrast and detail). This is soft light. It will generally make something like a Kasumi finish much more pleasing and even looking… when people say ‘afternoon light Kasumi appreciation’ this is what they are talking about in terms of the quality of light.

In your example the light source is reflected in the shot from above and it’s hard. That will mean that the point it’s reflecting from will show more detail and scratches. Where the light is not directly reflecting from it is lit by the light bouncing around the room and that light is much softer and you won’t see the details.

To make sure this is not the case tilt the blade and make sure you’re not seeing the same scratch pattern as you bring different parts into direct contact with the light source.

I keep meaning to do a video on lighting for knives to explain it correctly. Just make sure it’s an actual low and not a ‘trick of the light’ before you thin.

For straightening it just takes some time to train your eyes. Make sure the knife isn’t too close to your face as your eyes have a minimum distance they can actually focus( thats why your nose is blurry right now). For me it’s at least 8 inches but will vary between people. You are training your eyes to be able to gradually shift focus down the blade road. That is not something your eyes are used to so it will just take some practice and you will get more and more accurate the more you do it.

There must be another way to do it. Maybe a laser level . I still miss small bends especially on thin knives. Between what the stone is telling me and my eye I’ll figure it out eventually but it can be frustrating.

Still trying on the straightening visual test. With one eye and the edge/tip straight towards my eye, I can't see any blade road. There isn't enough distal taper to offset the effects of distance. With both eyes open, and blade centered between them, I can see the blade road(s), but (as expected) my brain interprets the images as an "X" whose center moves as the point of focus moves, and I can't make any sense out of what I see that way. Any further ideas welcome.

 

[refcast]

If you have a beater or are willing . . . . Intentionally bend a knife, and bend it back. Or make compound bends. A regular bend is a V shape. A compound bend is a U shape. Multiple compound bends are S shape. Then do smaller and smaller bends to see if you can see them, or what force makes the knife hold a bend. Works best with clad knives

 

[noj]

If you have a beater or are willing . . . . Intentionally bend a knife, and bend it back. Or make compound bends. A regular bend is a V shape. A compound bend is a U shape. Multiple compound bends are S shape. Then do smaller and smaller bends to see if you can see them, or what force makes the knife hold a bend. Works best with clad knives

I tried this on a flexible stainless knife, so I could readily change it's shape with my fingers, and would snap back. I have a couple junky knives I suspect are bent. Can't determine anything, other than wobbles looking at the spine on the stainless one.

First, I don't know how I should be looking (one eye or two, guessing one eye). Second, I don't know what I should be looking at (if it's the blade road, I can't see it, or I have to tilt right or left - in which case I can't determine anything). I can sort of see the spine, but not well enough to focus if it's shiny or featureless. I can't focus on anything looking at the edge (except the occasional spots of dust that come off when you touch them). Third, I am doubtful that this process is accurate enough for polishing. Form an experiment, the thickness of black sharpie ink appeared to be enough to throw off testing for flatness (on ~1k stone), and I doubt that's even visible, even with the "right" technique. I don't doubt that you can fix gross bends for regular sharpening - assuming you have a workable technique, which I don't - yet.

 

[KenjiF]

I tried this on a flexible stainless knife, so I could readily change it's shape with my fingers, and would snap back. I have a couple junky knives I suspect are bent. Can't determine anything, other than wobbles looking at the spine on the stainless one.

First, I don't know how I should be looking (one eye or two, guessing one eye). Second, I don't know what I should be looking at (if it's the blade road, I can't see it, or I have to tilt right or left - in which case I can't determine anything). I can sort of see the spine, but not well enough to focus if it's shiny or featureless. I can't focus on anything looking at the edge (except the occasional spots of dust that come off when you touch them). Third, I am doubtful that this process is accurate enough for polishing. Form an experiment, the thickness of black sharpie ink appeared to be enough to throw off testing for flatness (on ~1k stone), and I doubt that's even visible, even with the "right" technique. I don't doubt that you can fix gross bends for regular sharpening - assuming you have a workable technique, which I don't - yet.

One eye. If your eyesight is okay and you are able to focus on something a foot from your face then lighting is the key. I'm sure you can sight down a piece of paper or a dollar bill and see the curve at the edge. The thickness you are looking at isn't much thinner than that, the difference is the contrast between the background and the edge of your knife. The edge being thin and steel it isn't going to reflect light unless it is at exactly the right diffraction angle so you're most likely to see a silhouette or dark line along the edge. That is why I recommend looking into a light source or at least a light background to get the most contrast you can.

Try taking the knife into different lighting environments and seeing if you can see any better. To begin with, I had to set up a 'spot' that made seeing bends easier, and after I got better at it I can do it now at my sharpening station.

 

[noj]

One eye. If your eyesight is okay and you are able to focus on something a foot from your face then lighting is the key. I'm sure you can sight down a piece of paper or a dollar bill and see the curve at the edge. The thickness you are looking at isn't much thinner than that, the difference is the contrast between the background and the edge of your knife. The edge being thin and steel it isn't going to reflect light unless it is at exactly the right diffraction angle so you're most likely to see a silhouette or dark line along the edge. That is why I recommend looking into a light source or at least a light background to get the most contrast you can.

Try taking the knife into different lighting environments and seeing if you can see any better. To begin with, I had to set up a 'spot' that made seeing bends easier, and after I got better at it I can do it now at my sharpening station.

For background, I tried a trouble light with large reflector, LED light (not blindingly bright), and a sheet of printer paper over it. The background was quite bright and uniform. I tried some other things with more texture.

My eyesight is pretty good, a bit nearsighted, but the target isn't 12 ft away.

Are you looking down the edge, spine, both? I know you said edge, from which I assume the blade is edge up. When I tried this, all I could make out was vague distortion around the silhouette, probably reflections from the polished bevel. I am not sure how you would change the point of focus along the blade (I think you mentioned this), both because one is looking at a silhouette, and the edge itself has no surface to focus on.

Will try again, but sot sure I get it yet.

 

[refcast]

Yeah, straightening is more of a thing for sharpening, before staring sharpening. At the stage you're at, it shouldn't matter too much.
The bevels have been evened already.

(Sorry this is wordy)
I can look down the edge to see how it's centered . . . I can see the thickness of the knife in the blade road behind it. I can see whether the edge is closer to one side of the spine. If I hold the knife with the tip facing my eye, I can tilt the knife left or right, or tilt it up slightly and tilt the knife left or right. I want to see if the knife edge looks straight. . . It's easier to see curves this way. If I look at it straight, I should see a straight line. If I tilt it left or right, and I see a curve, or curves, then I straighten at those locations. Looking this way too, I can see thickness behind the edge, or whether a knife thicker right behind the edge on the left or right side, or where along the blade.

I'm really near sighted, and I'm kind of able to do this. Glasses for astigmatism can make lines look like curves, so that's a factor.

My light setup is just a ceiling light. I'm under the light, and look at the knife against a white wall about 5 feet away.

I look at the spine straightness to see for warps . . . If the edge and spine are not straight together I need check the blade face if it's bowed or curved. If it is. . . .bending can't fix it and I need to hammer

Another thing I could recommend is buying a strip of copper, iron, aluminium, or brass, and straightening or bending it. You can sharpen it too, to an edge, so you can see how light makes it look.

Yeah, stainless . . . Is not easy to work with when bending. I have to bend past where I want, for it to hold onto the bend j put in (in order to become straight)

 

[KenjiF]

Still trying on the straightening visual test. With one eye and the edge/tip straight towards my eye, I can't see any blade road. There isn't enough distal taper to offset the effects of distance. With both eyes open, and blade centered between them, I can see the blade road(s), but (as expected) my brain interprets the images as an "X" whose center moves as the point of focus moves, and I can't make any sense out of what I see that way. Any further ideas welcome.

Hey Noj,

I'm a bit confused by what you mean by 'I can't see the blade road' so I just wanted to clarify... Is it that with one eye you are unable to focus on any of the edge? Or your eyes are able to only focus on one point of the edge and the rest of the edge goes blurry so you can't judge straightness?

I'm going to give you the process I do step by step in as much detail as possible to try figure out what is going wrong.

You should be checking both the spine and edge with this method.

First I look down the edge or spine from the tip to the handle. I'll do this with my right eye and left closed. The longer the knife is the further away I'll hold it. The minimum distance will be 10 inches from my eyeball. The maximum will be my full arm's length. The further I hold the knife from me the more of the spine or edge I will be able to focus on but the less detail I'll be able to see. I'll angle the knife with the tip pointing down just enough so I can see the tip and the middle of the handle. Here I will do 2 things. I'll start with the knife further distance from my eye and get as much of the edge (spine in this case) as I am checking of the knife in focus as possible. This is where I can see gradual bends in the blade. If that is straight I'll bring the knife closer to my eye and train my eyes on the closest part of the edge and shift focus down the edge until I get to the heel. It helps me to slightly lift the handle as I do this so my eyeball isn't moving just changing focus distance (if that makes sense). Less of the edge I am checking in this case will be in focus but ill be able to detect small deviations in the edge this way. If I fix anything I repeat the same process again to check.

the two principles I think you should think about and test are.

Contrast- You need to make sure that there is enough contrast with the edge that you can see it. A light background and main source of light coming from
the direction you are pointing is the best bet. My ideal lighting conditions would be a light source slightly higher so you're not staring into it but its coming from the same direction and a white wall. If you can't see the edge at all I'd recommend taking something like a thin metal ruler into different lighting conditions and seeing where you can see the clearest. Then try blade road.

Focus distance- As objects get closer to your eye the less of them will be in focus. This is why even though your nose is in your visual field you can't actually focus on it. It will just look like a blurry blob if you try (with one eye). Try altering the distance from your eye to find what works best for you. Learning to sight a straight edge does require training your eye to be able to gradually shift focus (this comes w practice) but also where and how to hold your knife to see what you need to.

You could try folding colorful painter's tape tightly across the edge lengthways and see if that improves what you see. I don't think it will be as accurate but the color and added thickness of the tape might help while you're learning. I'm not sure where you're located but if you have access to a good pro sharpener you could also go in and ask them to run you through it.

If you get really stuck shoot me a msg and I can try walking you through it over Facetime.

 

[noj]

Hey Noj,

I'm a bit confused by what you mean by 'I can't see the blade road' so I just wanted to clarify... Is it that with one eye you are unable to focus on any of the edge? Or your eyes are able to only focus on one point of the edge and the rest of the edge goes blurry so you can't judge straightness?

I'm going to give you the process I do step by step in as much detail as possible to try figure out what is going wrong.

You should be checking both the spine and edge with this method.

First I look down the edge or spine from the tip to the handle. I'll do this with my right eye and left closed. The longer the knife is the further away I'll hold it. The minimum distance will be 10 inches from my eyeball. The maximum will be my full arm's length. The further I hold the knife from me the more of the spine or edge I will be able to focus on but the less detail I'll be able to see. I'll angle the knife with the tip pointing down just enough so I can see the tip and the middle of the handle. Here I will do 2 things. I'll start with the knife further distance from my eye and get as much of the edge (spine in this case) as I am checking of the knife in focus as possible. This is where I can see gradual bends in the blade. If that is straight I'll bring the knife closer to my eye and train my eyes on the closest part of the edge and shift focus down the edge until I get to the heel. It helps me to slightly lift the handle as I do this so my eyeball isn't moving just changing focus distance (if that makes sense). Less of the edge I am checking in this case will be in focus but ill be able to detect small deviations in the edge this way. If I fix anything I repeat the same process again to check.

the two principles I think you should think about and test are.

Contrast- You need to make sure that there is enough contrast with the edge that you can see it. A light background and main source of light coming from
the direction you are pointing is the best bet. My ideal lighting conditions would be a light source slightly higher so you're not staring into it but its coming from the same direction and a white wall. If you can't see the edge at all I'd recommend taking something like a thin metal ruler into different lighting conditions and seeing where you can see the clearest. Then try blade road.

Focus distance- As objects get closer to your eye the less of them will be in focus. This is why even though your nose is in your visual field you can't actually focus on it. It will just look like a blurry blob if you try (with one eye). Try altering the distance from your eye to find what works best for you. Learning to sight a straight edge does require training your eye to be able to gradually shift focus (this comes w practice) but also where and how to hold your knife to see what you need to.

You could try folding colorful painter's tape tightly across the edge lengthways and see if that improves what you see. I don't think it will be as accurate but the color and added thickness of the tape might help while you're learning. I'm not sure where you're located but if you have access to a good pro sharpener you could also go in and ask them to run you through it.

If you get really stuck shoot me a msg and I can try walking you through it over Facetime.

Hi Ken,

Thanks for taking the time for such a detailed write-up. I don't have a lot of time today, but wanted to answer your question.

When you mentioned blade road, I was envisioning the side of the knife (wide bevel, flat part, etc.), Using one eye, and looking at the tip with the spine straight away behind it, you can't see the side of the knife. Basically, a reverse choil shot. I figured the confusion might be terminology, and a hard to describe process.

So, thanks again for the detailed response. Will read through this carefully soon.

And also thanks @refcast for being "wordy"!

 

[refcast]

Oh, and I look with one eye.

Maybe a sheet of paper, too, or plastic. . . Anything haha, to practice straightening and seeing curves

 

[deltaplex]

Pictures can help quite a bit, too. I usually take some for reference and to verify what I saw with my eyes, once I start getting eye fatigue from looking down spines and edges.