What is this Shiny Line on Edge

[Kerneldrop]

This is an edge of a $30 Mercer.
What are the shiny lines? I didn't notice them until I was finished with the sharpening progression and looked at the edge under light.
They didn't go away with a few stropping passes on a 5k stone. Didn't go away with that felt block.
Not wanting to settle....I started over with a full-progression beginning at 320 and now it's gone, but I was just curious.
Maybe I applied pressure differently there? My guess is the edge bent over there from pressure?
Or it's just what happens with a $30 knife...i dunno.

[aporigine]

my guess is a persistent burr. If that’s a Millennia, it uses an unspecified “Japanese carbon steel”.

[Kerneldrop]

my guess is a persistent burr. If that’s a Millennia, it uses an unspecified “Japanese carbon steel”.

Thank you. So I need to look for that before going to a higher grit…and if I see it then I need to stay at that grit until it’s gone? I’m assuming that’s the only way to efficiently remove it.

[taz575]

If it was a burr, I would think it would be more on the edge apex instead of on the edge bevel itself?

Guessing its a spot on the bevel that wasnt fully polished, or a low spot? Or maybe a spot where you changed sharpening motion direction and the grit pattern caught the light differently?

[aporigine]

If it was a burr, I would think it would be more on the edge apex instead of on the edge bevel itself?

Guessing its a spot on the bevel that wasnt fully polished, or a low spot? Or maybe a spot where you changed sharpening motion direction and the grit pattern caught the light differently?

Within limits of resolution, it looks a bit proud of the apex to me. If that’s the result of optical illusion, my next best guess is a rolled edge. If it steels out, that might have been it.

I handle gummy burrs like this one might be by very light passes (alternating edge-leading and edge-trailing strokes and flipping the blade over every two to four such passes) until I can no longer see it under 20x.

[taz575]

Hmmm. When I zoomed in on my phone, it looks more like on the bevel itself. Looking at the pic on the computer no zoom, it looks more of a burr...lol. Go figure!

[jmcnelly85]

My guess is that this doesn’t have anything to do with being a Mercer or having a certain steel, instead I’m thinking the bevel has two different angles reflecting light differently. Moments like this are one reason I don’t trust a burr as much as a good light source. Angle A can form an apex, and even create a burr but the entirety of the bevel hasn’t been converted leaving angle B visible. Essentially, you formed a macro bevel. One area I look at before I jump from my coarsest stone is to make sure light reflects evenly from heel to tip. I’m sure the knife is sharp and will cut just fine but I’ll bet the second progression is more aesthetically pleasing.

[Kerneldrop]

...One area I look at before I jump from my coarsest stone is to make sure light reflects evenly from heel to tip. I’m sure the knife is sharp and will cut just fine but I’ll bet the second progression is more aesthetically pleasing.

That's what I'll do from now on. I always wait until I'm finished because maybe I like the suspense. ha
I'm still learning when to go to the next stone.
And I'm still figuring out if I get consistently better results when sharpening edge leading like Mark in his videos, or edge trailing like what's all over youtube. Right now I practice both leading and trailing, and with using both hands.

[Kerneldrop]

Hmmm. When I zoomed in on my phone, it looks more like on the bevel itself. Looking at the pic on the computer no zoom, it looks more of a burr...lol. Go figure!

It's definitely an inconsistency of some sort with my technique. After trial and error a few times I think the only way to efficiently remove it is to drop down to a courser stone. Otherwise I'm in for too many strokes on a finer stone for my skill-level.

I sharpened a Rada chef's knife with acceptable results and when I got to the end I had the same thing...so it's technique related.
I'm guessing I progressed too quickly.

[ex1580]

I've had some persistent burr issues in the past. It's usually a stainless steel but the Kanehide TK sometimes does it too. My solution is to try and get the knife "done" at about 500-600 grit (flat and even bevel, sharp enough to deburr and use). Then the 1-2k stone is just a little detail refinement. Deburr it really well after that and any stone higher is just a victory lap. This has worked for me. It's very frustrating to get done sharpening a knife and find a spot that isn't. I don't have a $30 Mercer but I do have a Victorinox that I don't bother taking over 1000 grit except for a quick strop, mostly to help deburr it.

[aporigine]

Hmmm. When I zoomed in on my phone, it looks more like on the bevel itself. Looking at the pic on the computer no zoom, it looks more of a burr...lol. Go figure!

It's definitely an inconsistency of some sort with my technique. After trial and error a few times I think the only way to efficiently remove it is to drop down to a courser stone. Otherwise I'm in for too many strokes on a finer stone for my skill-level.

I sharpened a Rada chef's knife with acceptable results and when I got to the end I had the same thing...so it's technique related.
I'm guessing I progressed too quickly.

T420 steel (Rada) is a poster child for soft “gummy” stainless. Something to try is to maintain angle but use very very light passes at the end. On these chewy steels, pressure on the stone tends to worsen burr formation (from what I read).

[STPepper9]

Watch out for a wire edge (burr) on those softer steels also, especially with edge trailing strokes. Try running the edge along a cork maybe, then a few more passes on the stone to finish.

[Kerneldrop]

T420 steel (Rada) is a poster child for soft “gummy” stainless. Something to try is to maintain angle but use very very light passes at the end. On these chewy steels, pressure on the stone tends to worsen burr formation (from what I read).

Rada makes me feel like a sharpening pro. lol
I'll get it to "razor sharp", go cut some air, then it's dull.

I sharpened the Mercer because it's 10.25"...so i'm slowly growing into sharpening a 240mm gyuto.
I have a Shibata Kashima 240mm sitting new in the box because I don't have the sharpening skills for it...I've been thinking about selling it.
I have the smaller knives down good enough for my home-use.

[ex1580]

I have a Shibata Kashima 240mm sitting new in the box because I don't have the sharpening skills for it...I've been thinking about selling it.

My Shibata Kashima 210mm is one of my favorite knives! That R2 steel can take a lot and the grind makes it always feel sharp even when the knife isn't. Don't overthink it! Just take your time and work in sections. The 500, 1k, 4k progression works well but if you can do something like a 500-600 to a 2k then it's one less stone and less chances to make a mistake, assuming you are using modern stones that cut well. Just give it a couple of laps on a loaded strop when you are done (something in the 1-3 micron diamond range) and it will treat you well.

[aporigine]

T420 steel (Rada) is a poster child for soft “gummy” stainless. Something to try is to maintain angle but use very very light passes at the end. On these chewy steels, pressure on the stone tends to worsen burr formation (from what I read).

Rada makes me feel like a sharpening pro. lol
I'll get it to "razor sharp", go cut some air, then it's dull.

I sharpened the Mercer because it's 10.25"...so i'm slowly growing into sharpening a 240mm gyuto.
I have a Shibata Kashima 240mm sitting new in the box because I don't have the sharpening skills for it...I've been thinking about selling it.
I have the smaller knives down good enough for my home-use.

what ex said!
That Kashima is a gem. You’ll go a lloonngg way on the ootb edge. By the time it’ll need a sharpening, your skills will be up to the job.

If I didn’t have one already, I’d heroically offer to take it off your hands at a modest discount. That’s just the kind of guy I am!

[Kerneldrop]

...By the time it’ll need a sharpening, your skills will be up to the job.

I'm going to get a smaller Ogata SG2 and practice with it... because that makes logical sense. At least that's what I keep telling myself. ha
I spy with my little eyes Ogata in stock...

[aporigine]

...By the time it’ll need a sharpening, your skills will be up to the job.

I'm going to get a smaller Ogata SG2 and practice with it... because that makes logical sense. At least that's what I keep telling myself. ha
I spy with my little eyes Ogata in stock...

I have his small nakiri. No bling but all swing. Shallots and smaller shrooms are its prey.

[atang]

This is an edge of a $30 Mercer.
What are the shiny lines? I didn't notice them until I was finished with the sharpening progression and looked at the edge under light.
They didn't go away with a few stropping passes on a 5k stone. Didn't go away with that felt block.
Not wanting to settle....I started over with a full-progression beginning at 320 and now it's gone, but I was just curious.
Maybe I applied pressure differently there? My guess is the edge bent over there from pressure?
Or it's just what happens with a $30 knife...i dunno.

I think you’re absolutely correct in that it’s just what happens with a $30 knife.
I can’t say for sure how these Mercer edges are finished in house. Many knife bevels that are machine finished not only have the coarse scratches, but are finished with a concave edge shape. When sharpening a new knife for the first time, the inconsistencies of the bevel really show themselves.
Knives are often finished in hand on a machine which also inherently produce minuscule high/low spots or even “holes” where there is faint overgrind (sometimes undergrind too!). Very hard to see on a new knife due to the uniform shiny finish (and often cut well enough out of the box too). I finished a kershaw this week with the same characteristics (I opted to leave them be as the cutting edge reached full functionality).
What the cropped photo looks like to me is a small variation in the factory grind that wasn’t sharpened through during the initial bevel set.
As I read through the thread it appears the coarse stone was able to work out that issue for you. This is a great example how hand sharpening actually creates a more consistent edge profile that has both strength and refinement.

[stevem627]

I actually found sharpening knives like Mercers was originally quite frustrating since I thought I should use high grit to get them really sharp. I found from reading forums that they just need 400 and then maybe 1000 or 2000 to be done. I use a cork to deburr and they get sharp and stay sharp for a decent time.

Sharpening better steels will be a necessary step forward and you can certainly do it. Don't get rid of a knife since you're afraid to try sharpening it...just refine your sharpening skills. It's not hard to get better, you just need some experience. I think perhaps your could learn nicely on a smaller knife, but eventually you will need to move up. Soft gummy stainless knives make you think you are worse at sharpening than perhaps you are.

Also, I think the one thing that gave me an AH HA moment was learning to reduce pressure while sharpening. The move up in grit means you need less pressure each step.

[Kerneldrop]

...This is a great example how hand sharpening actually creates a more consistent edge profile that has both strength and refinement.

This is what I keep telling myself as I progress. lol
I'm thinking about picking up a Shapton Glass 120 or 220 stone so I can play around with setting bevels.
320 is the coarsest I have, other than a few diamond plates.

I have a 1x30 variable speed belt sander, and a high speed buffer set up with MDF paper wheels. That's al I used until I picked up stone sharpening.
I haven't tried sharpening Japanese knives on the belt sander....I have a few 3M diamond belts that would probably do quite well, but right now I'm enjoying whetstone sharpening.