Sandpaper polish tips?

[instantramen]

About to try using sandpaper to refinish a kagekiyo wide bevel without having to flatten the hollow grind on stones -- looking for tips so I don't mess it up!

I'm thinking of doing a 400-800-1000-1500 progression using a cork or eraser, so not up to a true mirror finish, but aiming for a functional one that will erase any existing scratches on the bevel hopefully without the food stickage associated with a true mirror. Anyone have input on starting grit, or on using wet vs dry sandpaper vs mesh sanding sheets? Should I do a back and forth motion, or mix up horizontal and vertical sanding? Anything else you wish you'd known before starting?

 

[Martyfish]

About to try using sandpaper to refinish a kagekiyo wide bevel without having to flatten the hollow grind on stones -- looking for tips so I don't mess it up!

I'm thinking of doing a 400-800-1000-1500 progression using a cork or eraser, so not up to a true mirror finish, but aiming for a functional one that will erase any existing scratches on the bevel hopefully without the food stickage associated with a true mirror. Anyone have input on starting grit, or on using wet vs dry sandpaper vs mesh sanding sheets? Should I do a back and forth motion, or mix up horizontal and vertical sanding? Anything else you wish you'd known before starting?

The starting grit will depend on how deep the existing scratches are. If unsure, P320 grit is a pretty good place to start, because it can remove material but it's also pretty quick to jump up to finer grits if needed. I'd personally stop around P800 grit, which seems to bee a good middle ground between friction and stiction and is on the upper end of what I'd consider a working satin finish.

For the majority of the refinishing process you can use a push / pull movement, but you'll need to spend some time at your final grit doing just push or pull motions to avoid creating a horseshoe pattern when you change directions.

Changing the orientation of your sanding / polishing motion relative to the blade helps you to see when you have removed all the scratches from the previous grit due to the angle between the scratch patterns. That said, it's not always comfortable to do and is not strictly necessary if you very carefully inspect the blade for deeper scratches as you progress to finer grits. It is very annoying reaching P600 ish grit and realising that there are still some deeper scratches that you missed, so great care should be taken to have a clean and even finish at every grit.

Here are a few photographic guides that I made a few years ago covering refinishing, among other things:

 

[instantramen]

Thanks so much, this is exactly what I was looking for!

 

[Heckel7302]

I would advise keeping your direction the same, ideally down the length of the knife, if your first time. Removing lower grit scratches entirely is extremely time consuming.

It’s also ideal to use both hands. It’s easier to keep the push and pull straight. I made a little jig to help with this

Minus a jig, you can also just lay it down on a piece of wood with the handle off the end

I also like using a block with a piece of foam between the block and paper to help conform to the knife profile

 

[Just a DK]

So I just did this too.

I actually started on a 220 Imanishi stone to move the shinogi up a few mm and thin right at bte. I know I can't really do that that often however, i figured for one maintenance round it should be fine.

so progression was 220 -> 400 -> 600 on stone first. Very slow and checking basically every few swipes to slowly move up the shinogi and make sure i'm properly thinning the edge. I guessed that edge side needed more pressure due to harder steel to ensure a even thinning. I think the wide bevel here kinda helps make sure you can do even thinnings on both side if you are slow, use even pressure, count swipes.

Than I masking taped up to the shinogi line and went 400 -> 800 -> 1500 on 3m sand paper. rotate masking tape on each side of knife and shinogi repeat. I won't say perfect... but I don't think its an eyesore at least.

Below is result... with patina from use after. next time i'll be better with straight stroaks

 

[JPAU]

About to try using sandpaper to refinish a kagekiyo wide bevel without having to flatten the hollow grind on stones -- looking for tips so I don't mess it up!

I'm thinking of doing a 400-800-1000-1500 progression using a cork or eraser, so not up to a true mirror finish, but aiming for a functional one that will erase any existing scratches on the bevel hopefully without the food stickage associated with a true mirror. Anyone have input on starting grit, or on using wet vs dry sandpaper vs mesh sanding sheets? Should I do a back and forth motion, or mix up horizontal and vertical sanding? Anything else you wish you'd known before starting?

I’m thinking of doing the same (to a different knife). Super interested in responses to this thread too! Thanks for asking!

 

[rickbern]

I made a stupid little sanding block by gluing dense felt to a piece of wood. Almost like a fingerstone. 165 petty for scale. Petty could use some sanding!

 

[instantramen]

Found this video walking through a similar sandpaper progression to what I'm planning, and it looks helpful for visualizing the motions and effort spent at each grit:


He uses a progression of diamond pastes and an unknown "damascus makeover" paste to polish at the end -- any ideas about what I could use to achieve a similar effect (aside from natural stone powder I don't have)? Would simichrome work here?

 

[NickMinton]

The starting grit will depend on how deep the existing scratches are. If unsure, P320 grit is a pretty good place to start, because it can remove material but it's also pretty quick to jump up to finer grits if needed. I'd personally stop around P800 grit, which seems to bee a good middle ground between friction and stiction and is on the upper end of what I'd consider a working satin finish.

For the majority of the refinishing process you can use a push / pull movement, but you'll need to spend some time at your final grit doing just push or pull motions to avoid creating a horseshoe pattern when you change directions.

Changing the orientation of your sanding / polishing motion relative to the blade helps you to see when you have removed all the scratches from the previous grit due to the angle between the scratch patterns. That said, it's not always comfortable to do and is not strictly necessary if you very carefully inspect the blade for deeper scratches as you progress to finer grits. It is very annoying reaching P600 ish grit and realising that there are still some deeper scratches that you missed, so great care should be taken to have a clean and even finish at every grit.

Here are a few photographic guides that I made a few years ago covering refinishing, among other things:

this is pretty spot on. I don’t use any supporting backing on sandpaper or a jig, just the knife laid on a paper towel piece with the handle hanging off the side of the table

I change the scratch direction every grit by 45-90 degrees and usually go from 400 to 2-3k depending on how much time I have.

From there, I’ll usually add some stone powder to do an even kasumi finish on the cladding. See photos below, this is exactly what I did for a Fujiyama recently. Took about 2-3 hours

 

[labor of love]

I use wine cork but I wouldn’t mind trying new ways to apply sandpaper finish. 800 grit is my sweet spot and where I like to stop. Even going to 1200 the other day changed the blade enough to where I can’t wait to drop back to 800 grit. It’s worth playing around with so see what works for you.