Sharpening Knives

Paul

Well-Known Member
I did a search and didn't really find anything on this so I thought I'd start a thread about sharpening knives.

Yesterday, while traveling from Louisiana to Texas, I talked to my wife a little bit about the history of coticules and also their versatility. Although she's not into straight razors for her legs, she has acted like she'd be interested in sharpening razors and kitchen cutlery (she's just into learning new stuff). She's a science-oriented woman (Biochemistry Major and Biology Minor), and is intrigued by our research here in the Mess as well as the other aspects of this site that I told her about. So, she said she's like more information about how to sharpen knives (I can teach her how to sharpen razors).

I can sharpen a pocket knife, but I've never tried it on a coticule, and I've never done much of anything with kitchen cutlery.

I know some of you fine gentlemen are experts at sharpening kitchen cutlery, and I was hoping that you'd be so kind as to share some quality information on the topic.

Thanks in advance. :)
 

kinematic

Well-Known Member
There really isn't much to it. Make sure you have a stone with a decent working surface. What I do is I take a wet towel wich I lay on the countertop and place my stone on it so it doesn't move around. For kitchen knives I would recommend a 20 degree bevel. Take the knife by the handle, place the blade on the stone at the correct angle, lock you wrist and stabilize the blade with your other hand. Now make long even diagonal strokes across the stone. You want to keep as much of the blade on the stone as you can because it helps to keep the blade flat on the stone, hence the diagonal motion. You can start out with more pressure than you would use on a straight razor because most kitchen knives are made of softer steel. Once the bevel is set you can gradually lighten the pressure. If done corrctly you should be able to shave arm hair with it.

So remember, grab the handle, lock your wrist and stabilize the blade with your other hand. I put my thumb on the bottom of the blade and my fingers on the spine so I can hold the blade firmly (pulling motion). On the other side of the blade I place my fingers on the bottom and my thumb on the spine (pushing motion).
 

geruchtemoaker

Well-Known Member
lets see if I get it right
you keep a finger between the knife and the stone this to fix the angle? and with this hand you pull the knife?
and with your other hand you hold the razor down on the stone pushing it forwards?
 

Paul

Well-Known Member
Also, how do you know that you are at a 20º angle, and do you dilute slurry similarly as when sharpening razors?
 

kinematic

Well-Known Member
No, that's not what I meant. I'm right handed so that's the hand I hold the knife handle with. When I pull the blade towards me the bevel is facing me so I put my lefthand thumb at the bottom of the blade near the bevel and I put my fingers on the spine, that way I can hold it firmly and lock my hand in place to keep the angel consistent (there isn't enough room between the blade and stone for your fingers). When I go to the other side of the blade the bevel is facing away from me and I put my lefthand fingers on the bottom of the blade near the bevel and my thumb on the spine. That way I can again hold the blade firmly and lock my hand in place to keep the knife in the same position. I only hold the blade with my lefthand to ensure pressure and the angle is consistent during sharpening. I also lock my right hand in place with wich I hold the handle, that's the hand I use to make a forward and backward motion, my left arm just moves with it keeping the pressure and angle consistent.
 

kinematic

Well-Known Member
richmondesi said:
Also, how do you know that you are at a 20º angle, and do you dilute slurry similarly as when sharpening razors?
I'm a carpenter and I almost always sharpen my chisels to a 20 or 25 degree angle. After 16yrs of sharpening chisels I know exactly what a 20 or 25 degree angle looks like. I also dilute slurry during sharpening. When I put some water on the stone I keep the blade on the stone with my right hand so that the angle doesn't change.
 

Bart

Well-Known Member
When sharpening things free-handed, the ability to keep a fixed sharpening angle is everything. On knives squeezing the last bit of keenness out of the Coticule isn't as important as it is with razors. For kitchen knives, cutting vegetables on a wooden board will remove shaving sharpness withing the first few cuts. That doesn't mean that shaving arm hair isn't a very good test for checking the results after sharpening a knife, chisel or some other tool. But I wouldn't be bothering with hanging hair tests.

If you are in the habit of maintaining sharp edges on your knives/tools, as any professional cook/carpenter/butcher/etc does, a Coticule will work quite well for sharpening and touch-ups. But, in most households, knives are notoriously dull. Being a sucker for sharpness most of my grown-up life, I can't help myself to sneakingly check the edges of kitchen knives, whenever I see one of those nice blocks filled with expensive cutlery in the homes of my friends. Almost without exception, these knives are dull. Not butter knife dull, but still... If you throw a tomato to the edge of a knife and it bounces back...:-/ And the owners of these knives use them like that. My friends do that, my parents do it, even my wife does it. And I don't think they're exceptions. One may wonder what the point is of buying premium quality knives, that can take and hold excellent edges, if we'll be using them dull anyway. But I digress.
The bevels on such knives, that haven't touched a hone in a year or more, need preliminary work, before a Coticule can do any meaningful work. Certainly if the knives are of decent quality. In these cases it's best to restore a decent cutting bevel with aid of a coarser sharpening stone. Carborundum in the 300-ish grit range, or a diamond hone of similar coarseness is fine for that.

The most used sharpening approach is this:
Normally you just hone one side, with back and forth motions, following the curve of the blade, till a bur folds over at the opposite side. This can be easily felt with the fingernail: try plucking the expected bur as if it was a string, if it's there, you'll feel your nail skipping over it. Make sure the bur is present at the entire length of the blade.
At that point, turn over the knife and work on the other side till the first bur is gone and a new bur folds over at the other side. Again, make sure this condition is met at the entire edge.
Now the knife has a decent cutting bevel.
[note]If the knife was well maintained, this can be done with a Coticule. In that case, it's important to know that the bur created by a Coticule will be extremely small and harder to feel than the large bur left by man-made sharpening stones.[/note]

As said, the result totally depends on your ability to keep the honing angle constant. You need to focus on that real hard, and as Kinematic already pointed out: lock your wrist and do not allow the angle to vary. I usually put the knife at 90° on the hone, divide that in half (45°) and once again, to find 22.5°, which is close enough for me.

In case you used a coarser sharpening stone to restore a decent bevel, repeat the entire process on a Coticule (raise bur on one side, flip the knife and raise bur on the other side.)
Flip the knife one last time and end with just enough "edge leading"-strokes to remove that last bur. It won't be more than 10-15 strokes, depending on the Coticule and its size.
Done. If your angle consistency is any good, you should be able to shave arm hair, but if not, the edge should still be good enough for decent kitchen-service. And by that, I mean that you can slice a tomato by throwing it at the edge.

As a rule, Coticule edges do not need to be steeled. Simply touch them up on the Coticule (water only), by making a few strokes on either side of the edge. Such maintenance strokes must be made frequently, at the first signs of performance loss.

Remember: keeping a constant honing angle requires experience. There are a few different tricks that can make it easier, but they don't replace practice.
You can fold a 22.5° angle with a sheet of paper, and use it as a visual aid to keep the correct angle.
Another possibility is to build a small angled support for the hone. This puts the Coticule at an angle and allows you to keep the knife horizontal, which is much easier for most people. But the downside is that slurry doesn't stay on the Coticule so easily.

Kind regards,
Bart.
 

kinematic

Well-Known Member
Bart said:
Remember: keeping a constant honing angle requires experience. There are a few different tricks that can make it easier, but they don't replace practice.
Listening is also an important part of it. If I don't hold the knife firmly enough I can actually hear if the angle changes during sharpening. The angle at wich I sharpen my knives makes a very specific sound because it's the only angle at wich the full width of the bevel makes contact with the coticule. If I change the angle ever so slightly only the tip or the part of the bevel nearest to the spine of the blade makes contact and the sound changes :) :rolleyes: :D :lol: :w00t: ;) :| :p B) :-/ :blush: :O :scared: :huh: :blink: :confused: :( :cry: :sneaky: :mad: :love: :sleep: :thumbdown: :thumbup:
 

tat2Ralfy

Well-Known Member
Outstanding chaps :thumbup:

now I want to sharpen our kitchen knives as well!

Best wishes
Ralfson (Dr)
 

sparq

Active Member
I'll play a devil's advocate here. I decided I did not want to dish/wear my cotis with knives so I got a large slab of dragon's tongue that is cheap and can take a lot of abuse. DMT 325 -> DMT 600 -> DT/slurry -> DT/H20 -> Moughton makes them scary sharp (they all shave arm hair now).
 

torbenbp

Well-Known Member
Pardon me gents...but waisting precious coticule for honing cutlery/kitchen knifes does seem to be a utter wast.

I have honed tens of thousands of cutlery knifes (old butcher and honemeister for some years)
and I do it this way :

A cheap ,slowly rotating water hone..that would be some 40-50 USD, 4-5 passes on each side of the blade or until burr can be felt or seen. Then 10 passes on a hard felt wheel loaded with white paste ( my felt wheel has got an almost mirrorlike,shiny black surface)

Voila! Arm hairs flying all over the place. And it takes max. 2 mins. for a knife.

Kind regards
 

kinematic

Well-Known Member
torbenbp said:
Pardon me gents...but waisting precious coticule for honing cutlery/kitchen knifes does seem to be a utter wast.
A coticule is a tool to me so I don't see it as waisting precious stone. Besides, Ardennes has something like a 100 year supply so if I wear one out I'll just order a new one :p I also don't want to have to go to an electrical sharpener every time one of my knives is loosing it's edge. A few strokes over one of my coticules and I'm good to go :thumbup:
 

mrmaroon

Well-Known Member
hoenstly, I don't see any problem with using a coticule on kitchen knives. Sure it does wear them faster, but if it gets down to a serious small thickness just reserve it for razors and buy a new one!

When I hone my knives, I always use a "Unicot" method. I don't use any tape of course, but I do up the angle a bit. I also start with thick slurry and dilute. You don't need to dilute like you would with a razor, because the knife will make slurry on its own. On a razor when I would dilute 10-15 times on my hybrid I dilute 4 times with a knife, if that helps. Also, if you fold a copy paper corner to the edge, and fold again(looks like half of an air plane) you will see a 22.5 degree angle.

I hone all my kitchen knives and my dad's boning/butcher knives. I go a little overboard and finish with Crox and a strop, but its all good! I have found that a steel is worthless to a point. If you lose a little sharpness, but not a lot, a steel will sometimes make the edge worse if it is a low quality steel. I do touchups instead.

Play around with it, knives are so big, you won't wear them down quickly! Do expect to spend more time than a razor depending on the size though.
 

torbenbp

Well-Known Member
I seem to have made myselff unclear...sorry. It was the coticule I was worried about not the knifes! ;) The coti surely wont wear the edge as much as a powered hone.

And as for the steel..that is something that really take loads of practise,even more than stropping a razor on a strop.

Sure didnt mean to offend you pleasure of honing on a coti,but I´m just too lazy for that in this case :rolleyes:

Kind regards
 

Bart

Well-Known Member
"Why waste a Coticule on anything else then razors?" is a bit of a silly question, in my opinion.

Let's say a guy has a few straight razors, of which he uses one daily. He also has a chefs knife and 3 or 4 smaller kitchen knives. Plus an everyday pocket knife. Let's presume he maintains all those edges himself. A Coticule could do it, and it's going to do that for several decades, probably even a life-time. I think Ardennes sells at least an equal amount, if not more, of their stock to knife sharpeners as they sell to razor sharpeners. The big sales argument seems to be that you won't easily find a whetstone that combines extremely fine results with a Coticule's outstanding abrasive speed.

Obviously everyone makes his own decision whether something is worth the price for the purpose it is going to be used for. But Coticules do have very peculiar advantages for sharpening tools, so the discussion whether it's a "waste" to use them for that or not, is a bit besides the issue here.

Sharpening knives is certainly not improper use for a Coticule.
That doesn't mean it's the only valuable solution.

Kind regards,
Bart.
 

Rosco

Well-Known Member
I'm getting quite interested in learning how to hone my own knives. I'm thinking that a coticule and/or a BBW would probably be the way to go for me. I have a few questions.
Is there a great difference between a BBW edge and a coticule edge for kitchen use?
Is there any general rule for recommended size for a hone for knives? I know a lot of this is personal preference but for razors I know most people would not recommend anything smaller than 6"x1" or so. Smaller is useable, but not ideal. What about knives?
Is it easier/better to use the coticule anong with the BBW, or does it make much difference?
 

kinematic

Well-Known Member
Rosco said:
Is there a great difference between a BBW edge and a coticule edge for kitchen use?
There's absolutely no difference between a BBW or coticule edge for kitchen use.

Is there any general rule for recommended size for a hone for knives? I know a lot of this is personal preference but for razors I know most people would not recommend anything smaller than 6"x1" or so. Smaller is useable, but not ideal. What about knives?
My prefered size for knife honing is at least 15x5 cm.

Is it easier/better to use the coticule anong with the BBW, or does it make much difference?
I only use my coticules. I also have a piece of bbw I bought a long time ago but I seldom use it because a coticule is much faster.
 

matt321

Member
I would recommend using a coarse hone like a 220 DMT or similar. Most folks fail because they only associate knife sharpness with super fine grit hones. Thus, they spend hours polishing "shoulders" and never actually establish a fresh bevel because their hone is too slow. You need to hold a constant angle and establish a flat bevel quickly or your angle grip will start to get sloppy. If you can't set a freehand bevel at 120, 220, or 325 grit, you sure won't do so at 4,000 grit. An knife edge set at 220 grit is very aggressive and feels very sharp. After you master the coarse grits then you can take it to the next level.

I like to hold my off-hand fingers against the spine to guide the blade and help hold a fixed angle. As I hone, the finger pads are brushing over the hone surface and the spine is elevated up under the finger nails. I change hands to hone the opposite side. So I make several sweeping strokes in one direction and then change hands to do several strokes in the other direction.

An expert can feel and hear when the blade is riding across the hone flat to the bevel, but that takes time to learn.
 

torbenbp

Well-Known Member
Gents

You are offcourse right..a coticule is very suited for honing knifes. Was feeling a bit grumpy the other day and in the light og that, my intentions were unclear. I apologize.

However, to me, a kitchen knife is a tool and nothing more;)
And as I only have one coti, I will use it only for honing razors. But if I had several cotis I might consider honing my cutlery knifes on one of them.

Kind regards
Torbs
 
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