What Would You Do? Thinning and/or Polishing

[HumbleHomeCook]

Alright KKF, I'm looking for how you would personally approach this particular knife. There's nothing special or strange about it, it's just the next one I'm likely to play with.

The knife is a simple but well executed Tosa-made Hatsukokoro iron clad/aogami 2, 210 gyuto. It has fairly distinct bevels at the shinogi lines. Performance isn't bad at all - good general purpose kitchen knife.

A Little Backstory: I almost always do some amount of thinning to my knives, even if it is just some light easing of the shoulders. I'm function-over-form oriented. I'm not a good polisher and a big part of that is I don't necessarily set myself up for success early. I drop down to a low grit, work until I've achieved whatever goal I've decided upon and move on. This often results in visible scratches and patchiness that I know won't cleanup on a higher grit.

I've yet to encounter a knife that doesn't have highs and lows and on one hand maybe I haven't applied the patience to even them out but I also always feel like I don't want to remove that much metal just to look nice.

All that said, I wouldn't mind getting better at making things work great and look alright too.

So I turn to you fine folks just for your own personal opinions and approaches. Not necessarily what you think I should do, but what you would do if it was yours. What would your goal be and how would you achieve it?

In our example below we have visible latitudinal grid lines. What grit would you start on? Would you start with longitudinal strokes? Angled strokes? Other? Would this be a multi-session project over time? What would your likely progression be? Would you sand by hand to make things even?

I know there are good tutorials out there and trust me, I've watched many. What I'm after here I guess is a little more personal. What you would do.

I realize there's info you don't have or wouldn't have until you personally examined the knife but hopefully you can make educated guesses sufficient enough to form an opinion.

Thanks in advance!

 

[KnightKnightForever]

@Jurrian

 

[user 16756]

I like Tosa region knives but IME they have some of the most uneven grinds I've ever seen and getting them really even just takes ages and ages and ages.

first step is to correct any bends. that alone makes evening bevels out way easier. then, well some edge evening/reprofiling may be necessary frankly.

then, I'd fill in the bevels with sharpie and hit a hard stone just to see where I was at and then probably just put it on the Debado 180. I don't love working with knives at that rough a grit, but you can always use the knife and sharpen a little bit every day. much easier than trying to tackle it all at once.

absolutely nothing wrong with these knives. I don't think they benefit much from a top tier finisher versus just a decent one, but they certainly take a nice enough polish to justify the effort if you like them.

 

[Jurrian]

@Jurrian

Hmm, hard stone, low grit to start. Debado is just so soft. Nakikawa 180 hard type is the best imo.
First set the line at the shinogi line, make it crisp and even. Then place your fingers at the forge weld line. A totally flat bevel is not so desirable. Then blend the parts on an awasedo. A soft suita will do fine, maybe some fingerstones to finish. I’m happy to answer questions.

 

[HumbleHomeCook]

Hmm, hard stone, low grit to start. Debado is just so soft. Nakikawa 180 hard type is the best imo.
First set the line at the shinogi line, make it crisp and even. Then place your fingers at the forge weld line. A totally flat bevel is not so desirable. Then blend the parts on an awasedo. A soft suita will do fine, maybe some fingerstones to finish. I’m happy to answer questions.

Thank you.

"Hard stone, low grit." I have Shapton 220, 320 and SG 500. Thoughts?

 

[M1k3]

Start on 60-120 grit sandpaper.

 

[tostadas]

First thing I'd look at is whether the grind is flat or hollow, and if hollow, how deep it is (highly doubt it is convex). From there, you'll need to figure out how much removal is gonna be required. Likely that removal will come in the form of raising the shinogi,and maybe some thinning behind the edge depending on current thickness.
In any case, if you want an even polish on stones, you're going to have to at least get down to the lowest spots in the grind. So prepare to bust out the coarsest stone u got and just start working til all the original grind is gone. Then work your way up grits, removing all of the previous ones. Kinda depends in your stones, but I can go 300, 1k, 2k, 6k and get a decent base to work with for naturals after.
An alternative method would be to leave the existing geometry, and remove the stock grind marks with a sandpaper progression. Id go something like 220,400,600,800,1500, using some sort semi dense backing like cork that can conform to the highs and lows of the blade. I don't like dropping down to 120, but you certainly could. For hard abrasion resistant steels (*cough* TF) , this method absolutely sucks and you will hate yourself for trying. You can leave the knife with sandpaper migaki or follow up with finger stones after. I used this method for the Kyohei shindo I cleaned up for a friend (you can probably find some of my old postings).

 

[ian]

I feel like if you’re trying to make it an even grind it’s gonna require so much metal removal it hardly matters what the geometry is currently… that said, it looks concave in the choil shot, although I’m often misled.

Prob a multisession project. Start somewhere between angled and perp to the edge. Eventually, as you climb grits you want to end up so you’re finishing parallel to the edge. That usually gives the best finish, for reasons I can’t articulate. Probably it’s because the curvature of the grind (say it’s convex) is in the direction perpendicular to the edge, while the knife is flatter in the direction parallel to the edge, so you get a longer stroke of contact without having to rock the knife. Or maybe it’s just that you can make longer strokes, and those leave more uniform scratch patterns.

Also, sanding by hand hardly ever makes things even. Usually it makes things more uneven. The point of hand sanding is to cover up an uneven grind, since your sandpaper can get into concavities where a stone can’t. …. Oh wait, probably by “to make things even” you meant make the finish even, not the geometry. In that case, it sort of depends how good a job you do on stones. If you end up still having significant low spots, you’ll have to cover them up somehow if you want a clean finish, and sandpaper is how I’d do it.

For progression, just climb grits, using whatever you have and starting as low as you have. If you have a nice natural finisher that’ll be helpful. Harder stones will generally leave more perfect geometry, and make sure your stones aren’t dished if you want a nice clean shinogi line with no additional scratching. At least, I like flat stones, although some people seem to feel fine working on a halfpipe…

 

[Justinv]

I’ve been trying to get better at this too and recently did a similar project. I haven’t figured out a kasumi that looks good yet, but mirror isn’t hard. I also have a bunch of shaptons and don’t plan to buy any jnats.

Per suggestion above, a multi- session project. After the first session of thinning and polishing it up, the undergrinds you missed are all visible.

For the second or later sessions, mark the bad spots with a sharpie because you can’t really see much once the 220 scuffs it up. Take photos of the blade with sharpie marks since you will forget where they are.

My last project started with SP220 perpendicular to the edge. It looked blotchy after SG500 perpendicular so I switched to parallel to the edge. I stayed parallel to edge for SG1000, SG4000 and it looked streaky and bad. A Morihei 9000 looked better but not great. The real fixer for everything was a 1u diamond loaded balsa strop. It leaves a mirror finish. I presume others at this point would hit their preferred stone powder, fingerstones, etc. I am happy with the mirror.

Here is SG4000

Here is after loaded balsa.

Suggestions welcome.

 

[Jurrian]

Thank you.

"Hard stone, low grit." I have Shapton 220, 320 and SG 500. Thoughts?

Should be fine. Keep them flat with an atoma 140. You can pm me for more questions.

 

[Jurrian]

Start on 60-120 grit sandpaper.

If you go sandpaper then go sandpaper all the way. Low spots will prevent awasedo to do its magic. Then fingerstones could do the trick.