Questions about resurfacing stones

[Bigbbaillie]

I have some questions about resurfacing/retexturizing stones with SIC powder.
Namely I'm just confused about what grit to use, how often to resurface, and for what stones.

I've heard ~60 grit for coarse stones, and ~220 grit for medium grit stones, but what about finer stones (3000+)?

How often should one ideally resurface stones, does this change as you go up in grit? Is it generally just mostly by feel when a stone starts glassing over?

What about with nats, do you guys still feel like some of those stones need resurfacing eventually?


I know these are some noobish questions, but I mainly am asking because I have a sg120 that feels like it's doing nothing, so I'm fairly certain I need to resurface it. But it has made me think about the state of some of my other stones and whether it would be worth it to stock up on a range of SIC grits to resurface those stones a little more regularly.

Happy to check out other useful threads I may have missed as well if they are out there.
Thanks.

 

[MowgFace]

What knives are you refinishing?

 

[Bigbbaillie]

In terms of materials a little bit of everything, more specifically an iron clad Maz, a w#2 Ashi, and a semi-stainless Kaeru. But I also spend a decent amount of time with some cheaper stainless knives.
I've only recently started feeling confident enough to start doing work on some of the nicer knives so a lot of it is still practice/learning.

 

[MowgFace]

Unless you are trying to stone refinish the resurfacing scratches shouldn't matter. The deep scratches that are left can speed up sharpening and will smooth themselves out during use.

Unless you are going for all stones to refinish, there is no negatives to the deep scratches. At least in my experience.

 

[spaceconvoy]

Unless you are going for all stones to refinish, there is no negatives to the deep scratches. At least in my experience.

They wear down stone material faster. Yes, it speeds up sharpening because it helps release abrasive, at the expense of stone longevity. Not sure how big of an issue this is because testing would require years, but it's something to consider if you have any collector grade naturals.

 

[Bigbbaillie]

Okay that's good to know. I guess that makes sense though since the grit remains the same but you are in effect only changing the microscopic topography of the stone.

 

[stringer]

Okay that's good to know. I guess that makes sense though since the grit remains the same but you are in effect only changing the microscopic topography of the stone.

I have no idea what grit mine is. I bought a pound of "coarse" several years ago I use it on pretty much everything (synthetics, naturals, jnats etc) with a piece of granite tile in a sheet pan to catch the mess. I use some water, not a lot, so there's a thick sludge. Some people use a lot of water in a sink but I don't want that stuff in my drains. I very rarely worry about deep scratches. I don't do it often enough to worry too much about stone longevity. SiC lapping is also nice for reconditioning stones that glaze like superstones or a king 320.

I also have several two sided hardware store/Chinese grocery SiC brick oil stones. I use them with water and loose SiC to help counteract coarse stone dishing and glazing on the fly. For coarse stones the coarse scratches just make everything faster for me. But I don't put too much emphasis on aesthetics. YMMV.

For my razor finishers I will do my Arks and Jaspers first (extremely hard) and let the coarse SiC sludge break down into not really a slurry but more like a greyish black slime and then do my softer coticules and washitas. For synthetics I just go straight at it with the coarse stuff. If it's a fine razor finisher then I'll condition the stones by rubbing them together after SiC lapping. Rinse really well and you're good to go.

 

[inferno]

I have some questions about resurfacing/retexturizing stones with SIC powder.
Namely I'm just confused about what grit to use, how often to resurface, and for what stones.

I've heard ~60 grit for coarse stones, and ~220 grit for medium grit stones, but what about finer stones (3000+)?

How often should one ideally resurface stones, does this change as you go up in grit? Is it generally just mostly by feel when a stone starts glassing over?

What about with nats, do you guys still feel like some of those stones need resurfacing eventually?


I know these are some noobish questions, but I mainly am asking because I have a sg120 that feels like it's doing nothing, so I'm fairly certain I need to resurface it. But it has made me think about the state of some of my other stones and whether it would be worth it to stock up on a range of SIC grits to resurface those stones a little more regularly.

Happy to check out other useful threads I may have missed as well if they are out there.
Thanks.

you can resurface and flatten coarse stones with 60-120 powder.

the grit gets finer the longer you work it. it beaks down. so when flattening a 1k stone you might start with 60 grit, and after a few minutes that powder is 3-400 or so.

for finer stones 1k and up you can use any other stone to deglaze/declog them. i use diamonds on 1k and up, then if i see deep scratches from the diamonds i simply rub 2 stones together.

for my 8-12k stones i simply rub them together.

 

[MowgFace]

then if i see deep scratches from the diamonds i simply rub 2 stones together.

This is what I used to do until Jon said resurfacing was unnecessary.

I remember people on another forum Complaining about grit contamination, but I never had even a single stray scratch from it.

 

[inferno]

yeah its not necessary. only for looks i guess. for my high grits like 8-12k though. i want them completely flat and smooth. all stones will wear smooth again pretty fast though.

 

[inferno]

however when working with sic powder and medium grit stones it could be nice to be completely sure you dont have any sic powder left on there! it will completely ruin a finish. ask me how i know..

thats why i always rub medium grits against each other or with some nagura/cleaner after sic.

 

[DavidPF]

I don't want that stuff in my drains.

Dense, heavy sand in a drain does sound like a plumbing disaster.

 

[tostadas]

For my synthetic stones, I use anywhere from 60-220 grit loose sic. It really doesn't make much of a difference from what I've found.

However for natural stones which I intend to polish with I use a diamond plate so as not to embed loose grit.

 

[Bigbbaillie]

I like the sound of getting a silicon carbide brick for on the go resurfacing as @stringer mentioned. The sg120 can glaze over pretty fast so it would be nice to have something to fix that on the go for more extended thinning/sharpening sessions.

Also good to know that an Atoma or other stones will work for this on finer stones, my wallet definitely appreciates that.

 

[Luftmensch]

I have a sg120 that feels like it's doing nothing

Topical! We were talking about the shapton 120 over at Slowest wearing medium grit synthetic? That stone is notorious for glazing over!

If you are wrapping your head around stones... keep the ideas of flattening, resurfacing/dressing and slurry generation distinct. Of course they intersect and can occur simultaneously.

SiC grit is primarily used to flatten stones against a granite or glass surface. You can use it to resurface/dress a stone but I think that is a finicky way of doing it. You can also add SiC grit to stone slurry if you want to spice it up and experiment with more aggressive cutting.

The more modern way of flattening stones is to use a diamond plate. You can also use the diamond plate to resurface/dress a stone and simultaneously generate slurry. Personally, I have not noticed the difference between resurfacing the shapton 120 with SiC grit versus an Atoma 140. When the surface abrasives are rounded/exhausted, the cutting speed falls off a cliff. If you choose to use a diamond plate on hard, low grit stones like the shapton 120, you have to accept that the diamond plate will blunt quickly. I use an old worn out Atoma 140. It takes only a few passes to refresh the surface and generate a small amount of slurry. While the plate is probably half as keen as it used to be... I get the impression it is going to stay functional on the shapton 120 for a long, long time.

Then there are naguras. You can use naguras to resurface/dress a stone and to generate slurry (if you want). It depends on the stone and the objectives. I'd only use naguras on midgrits and higher (otherwise you are needlessly wearing away your nagura). Note that you wouldn't use a nagura to flatten a stone!!

How often should one ideally resurface stones, does this change as you go up in grit? Is it generally just mostly by feel when a stone starts glassing over?

So remember there are a few things going on here. Flatness and glazing....

Stone flatness is a personal preference. It matters more for single bevelled knives (Usubas, yanagibas). It also matters more for things like razors and chisels etc... It is likely that the more experience you get with sharpening... the more you will tolerate a degree of dishing in your stones.

But! If you are going to be particular about stone flatness, i think it is easier to flatten as you go. That is... do lots of small flattening often rather than a big one infrequently. For instance, once your sharpening session is done, finish the process by flattening your stones for the next session.

Glazing depends on the stone. If you want to keep your cutting speed high you might need to do it often. For the shapton 120... that means every 30-60 seconds for me! How do you know? Resurface the stone. Now take note of how it is cutting. When you feel that cutting speed has plateaued, if you want that original cutting speed, it is time to resurface!

What about with nats, do you guys still feel like some of those stones need resurfacing eventually?

This goes as much for synthetics as it does for Jnats... some stones will release abrasives during use and avoid glazing/clogging. If you manage the slurry well, you wont need to resurface these stones during use (although you will have to monitor flatness and adjust to your taste).

The higher the grit and the harder the stone, the more likely the surface will glaze/clog. At that point the action moves more from cutting and abrasion to burnishing. Not only will you likely feel a subtle difference in honing, the surface will change. On synthetics you might see metal/swarf embedded in the surface. On naturals, you might see the glazed surface look shinier (when dry)! You can use your preferred method to refresh the surface.

For kitchen cutlery I dont believe you need to worry too much about the scratch pattern left by diamond plates (or SiC bricks). Edge finishes above 3-4K are not so necessary... nor do kitchen knifes really need to be that sharp. In the spirit of completeness... the surface quality of a whetstone (e.g. diamond plate scratches) can matter for other sharpening tasks like razors or chisels/planes. You way well choose to create a super flat whetstone surface to chase a higher level of edge finish.


Lastly... to make things more complex... there is honing for shaping the edge... and polishing the bevel for aesthetics What you are doing will dictate how you manage the flatness, surface condition and slurry of your stone.

It is a big space to explore. Enjoy it

 

[M1k3]

"How do you know when the Shapton Pro 120 glazes over?"

When it stops feeling like it's trying to rip chunks out and more like gliding over rough glass.

 

[Kawa]

Yep, Shapton glass 120 is a pain.
Bought it for real heavy duty grinding, but after a few strokes it's a slick stone.

Resurfacing with coarse SiC brings it back to original, but only for a few strokes.


btw, so does the naniwa pro 400 (which many seem to love around here). Looses it coarseness extremely fast aswell.
In contrast to the chosera 600, which stays the same forever.
Day and night difference

 

[Bigbbaillie]

The more modern way of flattening stones is to use a diamond plate. You can also use the diamond plate to resurface/dress a stone and simultaneously generate slurry. Personally, I have not noticed the difference between resurfacing the shapton 120 with SiC grit versus an Atoma 140.

Appreciate how thorough your response was. I have been using the Atoma 140 to flatten the sg120 and while I found it definitely helps, as you have mentioned I feel like I need to lap it every 30 seconds in use otherwise it gets really glassy. I ended up purchasing some 60 grit sic powder in hopes that would create large enough scratches to give me a little more time before the surface of the stone gets glassy, we will see how that goes. Starting to think I might just want to get another coarser stone to replace the sg120, at times I feel like my sg500 cuts faster after factoring in all the time spent lapping.
Was thinking about going Shapton Pro 220 as a replacement, any thoughts? Mostly for thinning and removing lots of material.

The higher the grit and the harder the stone, the more likely the surface will glaze/clog. At that point the action moves more from cutting and abrasion to burnishing. Not only will you likely feel a subtle difference in honing, the surface will change. On synthetics you might see metal/swarf embedded in the surface. On naturals, you might see the glazed surface look shinier (when dry)! You can use your preferred method to refresh the surface.

For kitchen cutlery I dont believe you need to worry too much about the scratch pattern left by diamond plates (or SiC bricks). Edge finishes above 3-4K are not so necessary... nor do kitchen knifes really need to be that sharp. In the spirit of completeness... the surface quality of a whetstone (e.g. diamond plate scratches) can matter for other sharpening tasks like razors or chisels/planes. You way well choose to create a super flat whetstone surface to chase a higher level of edge finish.

Lastly... to make things more complex... there is honing for shaping the edge... and polishing the bevel for aesthetics What you are doing will dictate how you manage the flatness, surface condition and slurry of your stone.

I know Inferno mentioned above that he felt sic powder resurfacing, as long as the powder is rinsed off, doesn't really effect polishing at all. Wondering if you had any thoughts/experience with that in particular since you mentioned that.
Also you mentioned the proclivity of higher grit stones to load and start "burnishing" the edge as opposed to removing material. I have an sg6000 which makes it really easy to see this happening. I find with my knives I don't love the feel, but this would be a good thing for sharpening razors where you want to burnish the edge right?

Definitely enjoying the learning process though, before I joined the forum I felt like I was good at sharpening, then through reading and the search bar quickly realized how little I knew. It's a very niche hobby so it's hard to find people around me remotely interested so it's great to hear from others who have so much more experience.

 

[Kawa]

Appreciate how thorough your response was. I have been using the Atoma 140 to flatten the sg120 and while I found it definitely helps, as you have mentioned I feel like I need to lap it every 30 seconds in use otherwise it gets really glassy. I ended up purchasing some 60 grit sic powder in hopes that would create large enough scratches to give me a little more time before the surface of the stone gets glassy, we will see how that goes. Starting to think I might just want to get another coarser stone to replace the sg120, at times I feel like my sg500 cuts faster after factoring in all the time spent lapping.
Was thinking about going Shapton Pro 220 as a replacement, any thoughts? Mostly for thinning and removing lots of material.




I know Inferno mentioned above that he felt sic powder resurfacing, as long as the powder is rinsed off, doesn't really effect polishing at all. Wondering if you had any thoughts/experience with that in particular since you mentioned that.
Also you mentioned the proclivity of higher grit stones to load and start "burnishing" the edge as opposed to removing material. I have an sg6000 which makes it really easy to see this happening. I find with my knives I don't love the feel, but this would be a good thing for sharpening razors where you want to burnish the edge right?

Definitely enjoying the learning process though, before I joined the forum I felt like I was good at sharpening, then through reading and the search bar quickly realized how little I knew. It's a very niche hobby so it's hard to find people around me remotely interested so it's great to hear from others who have so much more experience.

Yes, I have the Shapton pro 220 aswell and it is a very good alternative for sg120. It is sliiiiiigghtly slower then the sg120 for the first few strokes, but the 220pro keeps its gritt! Maybe not exactly the same as original, but it doesnt get glassy, it just stays very coarse. Also, it doesnt dish that fast. For me, with my pressure it has the exact right balance between releasing particles without getting that crisping sound while sharpening from the loose particles and getting slick. I'd recommend it as a first in line coarse stone

 

[Luftmensch]

Appreciate how thorough your response was.

Pleasure! Your welcome!

Was thinking about going Shapton Pro 220 as a replacement, any thoughts? Mostly for thinning and removing lots of material.

I haven't used the Pro 220 (only 120 - as above). But I have used the Glass 220. It is fast stone - nice to use. I think it would be great for doing heavy work on really blunt bevels and removing small chips. For heavy thinning or regrinding/profiling, I don't think the value proposition is great. Although it works fast and is nice to use, it is probably the fastest wearing glass stone. It is also only 5mm!

I know Inferno mentioned above that he felt sic powder resurfacing, as long as the powder is rinsed off, doesn't really effect polishing at all. Wondering if you had any thoughts/experience with that in particular since you mentioned that.

I agree with that.

I think the term polishing is used fairly loosely. Everybody has their own personal definition of what it means.

As you go up the grit levels you are making the cutting edge less rough and more 'refined'. A side effect of doing this is that the scratch pattern becomes smaller and the edge becomes more polished. That is never my intention on the secondary bevel. I prefer to think about it as edge 'refinement' - after all that is why I am increasing the grit scale!

I dont find a need to go above 3-4K with kitchen knives. Depending on what you are cutting, a well done 1K can be perfectly serviceable. Kitchen knives simply dont need the same level of edge refinement as a razor or finishing plane. Grit contamination on kitchen knives? So long as it is negligible, I am not too concerned about it on the secondary bevel. Your edge might be an imperfect 3K with a minority of 400 scratches in it... but you wont notice. I would be upset if there was a rogue 60 grit SiC grain on the stone... but I dont see that happening.

What about the secondary bevel? That is a different story. Say you have thinned a knife you are proud of and you want to remove the scratch pattern from the primary bevel. You will move up the grit scale to achieve a smaller and smaller scratch pattern. Because this part of the bevel does not form the cutting edge everything you are doing is for aesthetics. I'd say this is 'polishing'. Depending on your objectives grit contamination can give you a really, really bad day. If you are trying to achieve a really uniform surface finish, one errant scratch can stick out like dogs bollocks. Bad luck... this might force you to take two steps back! Again, this wont affect the cutting edge... but the aesthetics might not be what you want...

Also you mentioned the proclivity of higher grit stones to load and start "burnishing" the edge as opposed to removing material. I have an sg6000 which makes it really easy to see this happening. I find with my knives I don't love the feel, but this would be a good thing for sharpening razors where you want to burnish the edge right?

Instead of working a glazed stone, I prefer to modulate my pressure or go up another grit level. Keep the stones cutting. The only times I might deliberately use a glaze stone is to debur an edge or to polish a bevel.

But you could potentially use it for refinement?? I dont know! I havent really tried

Definitely enjoying the learning process though, before I joined the forum I felt like I was good at sharpening, then through reading and the search bar quickly realized how little I knew. It's a very niche hobby so it's hard to find people around me remotely interested so it's great to hear from others who have so much more experience.

Hehe... well youre in good company! There are some gurus in these parts!!

 

[Bear]

I use 90 grit sic on my SG220, SG320, and SG500, I resurface my Ark with 400 grit

 

[Benuser]

This is what I use with the SG120.

 

[inferno]

i ran an unhardened hss piece on my 120 shapton for about 20 minutes. no loss of bite. it was finished on 60 grit powder.

every 5 minutes or so i scratch it up with my "norbide" boron carbide stick. seems to work.

 

[Luftmensch]

every 5 minutes or so i scratch it up with my "norbide" boron carbide stick. seems to work.

Does scoring the surface work? I had thought about cutting a cross pattern into the surface but decided it might not be worth the effort? If it helps prolong cutting, I will reconsider the option!

 

[M1k3]

Does scoring the surface work? I had thought about cutting a cross pattern into the surface but decided it might not be worth the effort? If it helps prolong cutting, I will reconsider the option!

It helps for me. I'll use the stone for grinding the spine for fixing broken tips. I try to make a criss cross pattern. In the end I just try to evenly spread it out.

Also works when breadknifing the edge.

It's not magic for the stone though. Just helps.

 

[inferno]

Does scoring the surface work? I had thought about cutting a cross pattern into the surface but decided it might not be worth the effort? If it helps prolong cutting, I will reconsider the option!

for me it seems to dislodge just enough abrasive from the 120 so the stone becomes self refreshing for a few minutes. its also done very quickly.

i guess the real test will come when i put hardened steel on there.

 

[Luftmensch]

It helps for me. I'll use the stone for grinding the spine for fixing broken tips. I try to make a criss cross pattern. In the end I just try to evenly spread it out.

Also works when breadknifing the edge.

It's not magic for the stone though. Just helps.

for me it seems to dislodge just enough abrasive from the 120 so the stone becomes self refreshing for a few minutes. its also done very quickly.

i guess the real test will come when i put hardened steel on there.

Thanks!

I might give it a go then... I was thinking about using an angle grinder blade with a thin kerf ~1mm... or perhaps a Dremel something... I'll give it some thought!