to flatten or not to flatten?

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Be EXTREMELY cautious about applying the info you read on BF to kitchen cutlery. I used to hang on there a lot and am familiar with most all of those posters. Member HeavyHanded is an excellent sharpener and I always paid attention to his inputs. You'll note, he may not strongly advocate using a flattening stone, but he is advocating that you learn to you use the stone in such a way that you keep it pretty flat in that way.

But, most of those folks are sharpening short knives that are also not very tall and many of them are sharpening simple steels. Further, the needs and expectations of their edges are often drastically different than what we want in our kitchens.

Benjamin of Baryonyx is another person I have a lot of respect for but again, he's focused on field tool use.

Flattening your stones is fast and easy and worth doing.
 
I am of the camp that you should try your best to minimize dishing in use, which leaves me flattening LESS (Tips and Heels on the corners, rotating the stone occasionally). That being said, i believe a flattening method is non-negotiable. To me, doesnt have to be expensive nor fancy. Just needs to be able to flatten your stone

I disagree largely with the members here who suggest flattening before and after each use, though its their money and they stone life.

It should be mentioned, that I am newer to natural stones so I cannot speak on the merit of fancy flattening methods for Naturals.
 
Flattening your stones is fast and easy and worth doing.
Not sure about fast and easy. I find it to be such a PITA, the second least favourite part of sharpening after heavy thinning. I agree that it worth doing though, 100%.
 
I try to use all of the stone. Keeping it mostly level. I do flatten my stones with a diamond plate every now and then to prevent them from being overly dished though.
 
I’d argue that the hilltops aren’t getting used anyway — if they were they wouldn’t be hilltops! So when the valley hits rock bottom all the hilly bits end up in the trash. That’s a lot of stone. If they’d flattened regularly, much of those hills would actually have seen use. So flattening means you get more out of your stones, not less! QED
 
I try to use the stone as evenly as I can...that being said I still have my stones dish... though not horribly...I do flatten... but not obsessively...if I can see it is dished I'll do something about it...if I can feel that it's sharpening unevenly than I'll do something about it....it depends on how much use the stone gets I find...

Before I begin... I'm not talking about a very dished stone...very lightly to lightly dished I think you can get away with...the ones where it's obviously dished need help...

Now...if I were to flatten every time I used would I be saving time... maybe...way faster to remove a tiny amount than really correct a badly dished stone... thought I try to not get there...I don't think that flattening very regularly decreases the life expectancy of the stone any more than having to spend longer when it is dished...

I think it's personal preference and that's about it...if you're free hand sharpening there's way more variations it's the nature of the beast...arms are meant to move...they do...so a stone slightly dished isn't as huge a deal as proper technique and angle retention...

Yes a perfectly flat stone does remove one of the variables...but I don't think it's the most important variable...

So yes by all means flatten those stones...but don't get obsessed...

Take care

Jeff
 
For sharpening I prefer quite flat stones. Im not fanatical about it in terms of flattening before, during, and after each session (at least not for kitchen knives), but I want things flat. I do my best to use the full surface of the stone, but inevitably over time some flattening is needed.

For polishing the story is a bit more complex. If I'm working on setting a crisp shinogi or flattening a hira, I may flatten every minute or two on my coarser stones. If I'm polishing a fully convex gyuto or reshaping the tip of a knife, I actually like slightly convex stones (like a toned down version of a sword polishers). But never do I see a benefit to using something dished.

Can you get a good edge off a dished stone, almost certainly. Do I see a reason to let stones get dished? Nope.
 
I flatten all my stones that are for edge sharpening. I don't really flatten my thinning stones though, even the fine ones. For thinning, I always start with or only use edges so my thinning stones are all like arch. Even my chosera 800 and 3000, I keep one side flat for edge and one side arch-ish.
 
I flatten all my stones that are for edge sharpening. I don't really flatten my thinning stones though, even the fine ones. For thinning, I always start with or only use edges so my thinning stones are all like arch. Even my chosera 800 and 3000, I keep one side flat for edge and one side arch-ish.
Similar approach actually. 1/3 of my synthetics have some convexity worked in and 2/3 kept quite flat.
 
Very interesting thread. Presents every point of view on the subject.

I’ve been sharpening since I was a kid … over 60 years. For the first thirty years I used a soft Arkansas stone (still have it) and old jeans or cardboard for stropping. I never gave a thought to flattening my Ark. My edges were good enough but I never considered myself anywhere near to being a “pro”. I retired about 25 years ago and got more serious about my knives, stones and sharpening. I started sharpening for others and developed a bit of a client following. I pretty much limit myself to kitchen knives. Top end knives get stones and lesser but good knives, and chisels get my Tormek T8.

I don’t reject the idea of flattening stones, but personally I don’t do it for the double edged blades I sharpen. I think it would be advisable for stones used for single edged blades but I really don’t get much call for sharpening them. When I do I’ll touch up a stone with an Atoma if I think it needs it.

Mostly I sharpen the parts of the blade that needs attention and wander around the stone to get the results I want. Tips will generally get the ends of whatever stone I’m using. I wouldn’t even think of saying that working with a flat stone isn’t a good idea. Obviously it is. I just think the subject is a bit more complicated than that. At some point I feel that I developed the fine motor skills in my finger tips and hands to obtain the results I was happy with. For me that took a couple of years ruining my mothers kitchen knives before I really got the hang of it.

I did enjoy watching Murray Carters sharpening videos. At that time I don’t think Carter was a strong proponent of flattening stones. I liked his idea of using an economical 600/1000 King combo stone. I used that combo for awhile but though I got satisfactory results I found them too slow for my liking. I also wanted a coarser stone to deal efficiently with knives which were damaged or very dull.

Carter then hooked up with Nanohone and changed his tune. I didn’t find his presentation convincing for me. But then again I can’t really argue with the idea that a flattened stone isn’t desirable. I just don’t find it necessary to get the results I want.

I think the subject gives truth to the thought that the most expensive equipment isn’t really a pre-requisite to obtaining great edges. Experience, practice and developed skills are probably more important factors.

Just my .02.
 
i try to use the whole stone surface when it suits me, but i'm not a master sharpener. if it's easier to just focus on sharpening itself, that's what i do.

i keep stones flat. it's easier for me to get good results on flat stones.
i grind them down like they owe me money.

i don't feel bad about burning up a stone. i'll be surprised if i burn up even a few stones in my lifetime.
 
Worried the stone will wear fast, is not a good argument in my opinion to determine if you flatten or not.

Lets say you are an average sharper, that's like 1 knive a week or so? Although I dont think the average home sharpener will do 1 knive a week for over 40 years, but lets say you do. Your stone will survive you, and your kid.
See @Brian Weekley 's soft arkansas for example, which he used for over 30 years and still has.
 
Worried the stone will wear fast, is not a good argument in my opinion to determine if you flatten or not.

Lets say you are an average sharper, that's like 1 knive a week or so? Although I dont think the average home sharpener will do 1 knive a week for over 40 years, but lets say you do. Your stone will survive you, and your kid.
See @Brian Weekley 's soft arkansas for example, which he used for over 30 years and still has.
no i am not worried the stone will wear fast i just don't have a method to flatten my very coarse stone 140 grit
 
jayfai1.jpg


I personally flatten, but apparently Ms Junsuta from Bangkok aka "Jay Fai" has been skipping it for forty odd years.

That didn't stop her from being recognised by michelin.

[These days she calls her michelin star a curse for causing long queues and selfies. A nuisance to other street vendors in her neighbourhood]

Different people different noises, just do what works for you.
 
Be EXTREMELY cautious about applying the info you read on BF to kitchen cutlery. I used to hang on there a lot and am familiar with most all of those posters. Member HeavyHanded is an excellent sharpener and I always paid attention to his inputs. You'll note, he may not strongly advocate using a flattening stone, but he is advocating that you learn to you use the stone in such a way that you keep it pretty flat in that way.

But, most of those folks are sharpening short knives that are also not very tall and many of them are sharpening simple steels. Further, the needs and expectations of their edges are often drastically different than what we want in our kitchens.

Benjamin of Baryonyx is another person I have a lot of respect for but again, he's focused on field tool use.

Flattening your stones is fast and easy and worth doing.
I'm on there a good bit now days. Though I generally stick to the knifemaking section a lot of good makers there. I've found this site is generally better for sharpening stuff, and tend to not really go venturing out of that particular section of bf.
 
As far as flattening.

I'm not religious about it, but I can say a couple things. On the coarse stones that are a pain to flatten (even with the right tools). It's pretty important to try to use it evenly so you can avoid flattening as often. I did that with. My 120 kuromaku until it was worn away. But with my bryxco manticore it's easy to dish the middle, and it does need a flattening every once in a while (not fun).

I can definitely say I get noticably better results from my edges with as flat as possible of a stone, and for that reason I will tend to make sure the stone Im finishing on is pretty near flat, it's also part of why I think I've moved on to finishing on my venev stones a lot more often than any other. They're always if not perfectly flat, close enough to not make a big difference.
 
i am afraid of the silicone carbide getting airborne that stuff is very nasty to inhale
You really don't need to worry about it when using it to flatten stones. You're doing it wet, which will generally keep anything from becoming airborne.

Also the size of these abrasive particles, are pretty big, although anything that breaks off will surely be smaller, but the water keeps in from flying into the air, and the surface tension helps it stay put, and form a slurry. Really much like when using a stone, or any other general wet abrading tasks.
 
Don't worry about inhaling SiC.
Those are big and heavy grains, way bigger then your average sand in your garden. When wet and windy, that doesnt smack in your face, right?
 
no i am not worried the stone will wear fast i just don't have a method to flatten my very coarse stone 140 grit
I have one of those Chinese grey stone that got really dished back in the days when I didn't know better. Brought it outside to flatten on the concrete street 🤣 Let's just say it wasn't worth my time.

I didn't even know about flattening my stones until I came onto this forum. I notice that I get better results and faster results with a flattened stone than not. I do the sharpening for my colleagues as well so it does get a bit dished ever so often. I flatten maybe once a month? Like others have said, try to use the whole surface of the stone.
 
You really don't need to worry about it when using it to flatten stones. You're doing it wet, which will generally keep anything from becoming airborne.

Also the size of these abrasive particles, are pretty big, although anything that breaks off will surely be smaller, but the water keeps in from flying into the air, and the surface tension helps it stay put, and form a slurry. Really much like when using a stone, or any other general wet abrading tasks.
what about when you pour it on the glass can it go airborne ?
 
If you’re worried about it, I’m sure you can get behind one of those facemasks that have become suddenly ubiquitous in the last couple of years… don’t hold your breath!
 
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Generally speaking, the coarser the stone the more often it will need flattening. But it depends a lot on your own style and what you're trying to accomplish. I tend to let my coarse knife stones get pretty dished out. But my razor finishing stones I lap all the time. The rest are somewhere in between. I have an atoma 1200 now for raising slurry and conditioning fine stones. Three stone method and/or SiC slurry on granite tile for everything else
 
what about when you pour it on the glass can it go airborne ?
These are not small pieces of sic. Much too large to go airborne. Especially the grits needed to flatten a 140 grit stone. They're like grains of sand or larger. Not a risk. Even if you are worried put water on the glass first. Also as suggested you can wear a mask. Though I don't think in this particular case it's necessary.
 
Generally speaking, the coarser the stone the more often it will need flattening. But it depends a lot on your own style and what you're trying to accomplish. I tend to let my coarse knife stones get pretty dished out. But my razor finishing stones I lap all the time. The rest are somewhere in between. I have an atoma 1200 now for raising slurry and conditioning fine stones. Three stone method and/or SiC slurry on granite tile for everything else
do you use a mask when using the silicone carbide?
 

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