"Microserrations" after sharpening

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chiffonodd

chiffonodd

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I just sharpened through a full progression on a white #2 gyuto (g ginga) for the first time - only had it for a few months so had previously only "touched up" the edge on high grit stones, not wanting to mess up Jon's initial sharpening job, which I knew I couldn't duplicate. Anyway, after going through the whole progression (1K, 3K, 8K, 10K), I've noticed a couple spots on the edge that appear to have extremely fine microserrations at the very edge. These are not chips, they are extremely small, almost invisible - they show up as glints of light more than visibly deformed metal, although you can see some slight deformation if you look hard enough.

At first I thought maybe I hadn't done a good enough job deburring, as that seemed the most obvious suspect. But I don't feel a burr when running my fingertips or fingernail laterally (perpendicular to the edge).

I did a fair amount of edge trailing strokes at the end of each grit, followed by hard felt, in an attempt to deburr. Could it be that some just stuck around, and I'm not feeling it because it happens to be aligned correctly? I haven't used it much since sharpening, so don't know if there is any quick degradation that could indicate wire edge.

What's likely going on and what is the way to fix it? Start over at 1K and try to deburring better?

PS: it is sharp as all get out, just looks a little off in some spots.
 
Edge trailing strokes don't do a good job of removing a burr; they can create a foil edge. I recommend running the edge through something to pull it off (at 4k and under, I use the unfinished wooden handle on a paintbrush, but cork and other stuff works fine), and go easy on edge-trailing strokes. If using hard felt, is there any abrasive being used? I sometimes use a few strokes on fine diamond grit on balsa, and after every 4 edge-trailing strokes or so, I'll run the edge through the edge of the balsa just to prevent drawing out another foil-like edge.
 
"Foil edge" is a great descriptor of what it looks like in those spots. The felt I was using is one of those hard felt blocks for cutting into - not a pad to strope on. I've got a wood paintbrush around here somewhere, will give it a shot thanks.

If it doesn't pull off the foil edge, will I need to re sharpen from 1K on up?
 
Try the rough side of a blue sponge. Don't cut into it, draw away from it at a 45 degree angle, multiple times on each side.
 
chiffonodd said:
"Foil edge" is a great descriptor of what it looks like in those spots. The felt I was using is one of those hard felt blocks for cutting into - not a pad to strope on. I've got a wood paintbrush around here somewhere, will give it a shot thanks.

If it doesn't pull off the foil edge, will I need to re sharpen from 1K on up?
Click to expand...
There are many strategies people will suggest and I can't claim that I can give you better advice. However, I have "jointed" edges before on very fine stones (basically do a very light slice on the side or edge of a fine stone to grind the very edge and burr off), and bringing it back with 4k or 6k is not hard at all...a few strokes with minimal pressure on each side ought to return the apex to a very good sharpness with minimal burr. I do this on razors and knives with good results and very little material loss or fatigue.

Going back to 1k seems a bit overkill for something small like a foil edge.
 
chiffonodd said:
Draw away meaning like scrape at a 45 degree angle, basically?
Click to expand...
Yeah, let the fibers of the scrubbie pull the very edge off like a wire brush. Should be gentle enough to do minimal damage to the very edge, and should be aggressive enough to remove most of the burr fragments.
 
chiffonodd said:
"Draw away" is ambiguous
Click to expand...
Don't worry about abrasive personalities...focus on abrasive sponges:
[video]https://youtu.be/XnhIKOX6Rco[/video]
I think around 7:45 to 8:00 in the video.
 
Thanks for the video link. Lots of useful info to absorb there.
 
Doesn't it depend on how small the microserrations are? If they are really really small, isn't that is a good thing? Gives you a toothy but sharp edge, no?

After all, if you strop on diamond balsa and look at the edge under a really powerful loop, you will see "microserrations" and isn't it the case that every edge has microserrations under sufficiently high magnifications. (Just askin :) )

Now macro serrations visible to the native eye are another thing :)
 
gic said:
Doesn't it depend on how small the microserrations are? If they are really really small, isn't that is a good thing? Gives you a toothy but sharp edge, no?

After all, if you strop on diamond balsa and look at the edge under a really powerful loop, you will see "microserrations" and isn't it the case that every edge has microserrations under sufficiently high magnifications. (Just askin :) )

Now macro serrations visible to the native eye are another thing :)
Click to expand...

Yeah I actually was thinking that it was nice and toothy, which certainly isn't a problem - BUT it probably should not be when polished up to 10K, right?? They are visible to the naked eye but barely. Also, the surest indication to me that something is "wrong" is the inconsistency -- the little deformations are only visible in a couple spots here and there, both locations no bigger than a couple centimeters. If I was doing something right and creating a toothy edge on purpose, hopefully it would be that way throughout :)

I liked "foil edge" as a good description, almost like the very edge was made of foil at that location and had been stretched and then torn. Probably the result of over stroping/edge-trailing in an attempt to deburr . . . Had the opposite effect and just pulled out a burr!
 
I bow heartily to Jon's expertise :)

but seems to me obvious if they are visible to the naked eye, they are a problem, if they are only barely visible at say 40X magnification and run the length of the blade, they are a good thing...
 
gic said:
I bow heartily to Jon's expertise :)

but seems to me obvious if they are visible to the naked eye, they are a problem, if they are only barely visible at say 40X magnification and run the length of the blade, they are a good thing...
Click to expand...

Yeah I think you are definitely right about that. Anyway I will try the sponge trick and see what happens.
 
So work got really crazy for a few weeks and I haven't had much of a chance to cook or work on the knife. Finally caught a bit of a break tonight - tried the sponge trick but no dice.

I think it's definitely metal that's been pulled too thin during sharpening (while edge trailing in an attempt to deburr) and tore at the edge, rather than any sort of chipping. Here are two pics. One for size/perspective and the other showing the deformation:

2wec5j7.jpg


2wq9wci.jpg


Notice how the edge is pretty clean on the bottom half of the photo, then hits that spot with the tearing.

So what do you think, just your plain run of the mill burr? I've already tried the rough side of sponge, cutting lightly into soft wood, cork, and felt. Think it's time to drop down to 3K (my lowest grit above 1K) and try to sharpen it out with edge leading strokes, then go back up through my progression?

Thanks KKF.
 
2wq9wci.jpg


Looks like a typical wire edge to me. Looks great after sharpening/deburring but fails in use.
 
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