Kitchen knives: Toothy edge vs Polished edge

[Sharpco]

My customers told me that "The knives dull too quickly" I thought about it and eventually came up with this idea.

"Maybe Honing is the cause?"

As you all know, kitchen knives are more often used for slice cuts than push cuts. So, in this case, the toothy edge is better than the polished edge. Perhaps just after sharpening, polished edges may be good for slice cuts too. However, even if it gets a bit dull, it doesn't do slice cut properly.

But this is not a simple matter. I faced three problems here.

1. Does the toothy edge help with the edge retention of the kitchen knives?(At least two weeks to a month)
(https://forum.tormek.com/index.php?topic=3240.0)

2. How coarse is the best for edge retention?

3. What type of abrasive is appropriate to make the toothy edge? I think compound & PA-70 are not good.

This is all about the regular stainless steel kitchen knife, but it could be extended to all other knives used for slice cuts.

What is your opinion?

[cbwx34]

My customers told me that "The knives dull too quickly" I thought about it and eventually came up with this idea.

"Maybe Honing is the cause?"

As you all know, kitchen knives are more often used for slice cuts than push cuts. So, in this case, the toothy edge is better than the polished edge. Perhaps just after sharpening, polished edges may be good for slice cuts too. However, even if it gets a bit dull, it doesn't do slice cut properly.

But this is not a simple matter. I faced three problems here.

1. Does the toothy edge help with the edge retention of the kitchen knives?(At least two weeks to a month)
(https://forum.tormek.com/index.php?topic=3240.0)

2. How coarse is the best for edge retention?

3. What type of abrasive is appropriate to make the toothy edge? I think compound & PA-70 are not good.

This is all about the regular stainless steel kitchen knife, but it could be extended to all other knives used for slice cuts.

What is your opinion?

I think step one is obvious.  If you think the honing wheel is the issue... stop using it.

I use a ceramic rod to finish most knives, especially kitchen knives.  Here's another thread you might find interesting.... Knife question for Stig ... and in particular this quote:

I have seen the same results. I used to give every knife a polished edge until a customer showed me that while it shaved it slid on a tomato skin. I gave that knife a couple of swipes on a ceramic steel and it sliced like it was meant to. We use that same ceramic steel in our kitchen to touch up between sharpenings and I now finish 90% of my knives with a 1500 grit ceramic wheel. High-end Japanese knives with 15% bevels I still polish.

Another thread you might find of interest.... How sharp is sharp?

If you need to use the honing wheel... use it just enough to debur... not to refine the edge.  There's a difference.  You can also use it on just the side of the knife with a burr... make sure the burr is on one side, and make 1-2, higher angle pass to remove it.  (This works best if most of the burr is removed on the sharpening wheel first).  Do just enough to remove the burr.

(A search for "ceramic" will give you other threads you might find of interest).

[grepper]

The problem with polished edges is that they roll into one even, round dull roll of steel at the edge.  From my experience this happens quickly.

I prefer a 150 grit finished edge, debured without compound.  Remove the burr but don't remove the tooth.  As you have noted, compound is an abrasive and will smooth out the "toothy" edge.  IMHO, smooth edges are good for shaving and push cutting.  For slicing and general useful edge retention a toothy edge is the way to go.

You might enjoy this entire post, but here is a comment from a guy who sharpens/rents knives into restaurants:

http://bessex.com/forum/showthread.php?tid=68&pid=614#pid614

[Ken S]

I would like to add that Grepper is not just a computer guy. He has put a lot of time and work into studying knife edges. He has very generously shared this information. He is a leader in using USB microscopes and BESS measurement with knife edges.

Ken

[cbwx34]

The problem with polished edges is that they roll into one even, round dull roll of steel at the edge.  From my experience this happens quickly.

I prefer a 150 grit finished edge, debured without compound.  Remove the burr but don't remove the tooth.  As you have noted, compound is an abrasive and will smooth out the "toothy" edge.  IMHO, smooth edges are good for shaving and push cutting.  For slicing and general useful edge retention a toothy edge is the way to go.

You might enjoy this entire post, but here is a comment from a guy who sharpens/rents knives into restaurants:

http://bessex.com/forum/showthread.php?tid=68&pid=614#pid614

Nothing new about a "toothy" edge... particularly on low end steels.  Think Ginsu, or Cutco's "Double-D" edge, (or any knife that advertises "Never Needs Sharpening!")

If you're sharpening lower end steels and/or for users that abuse their knives... might be worth considering keeping your stone graded "coarse", use a minimal debur method, and see what feedback you get.

The tradeoffs are obvious... rougher cuts, and less precise cutting being the main drawbacks.

[Sharpco]

Thank you, everyone.

SJ stone seems to be the problem. This seems to remove the knife's teeth very effectively. Even more than honing wheels.

[Stickan]

Hi,
I don't agree at all.
If a knife get dull to quickly it's more likely that there was to much burr left on it. To then use a steel on it, if you don't know how to use it, will get it even worse.

I sharpen my knifes at home 1-2 times a year and I use the honingwheel 3-4 times to keep them in shape. There is no burr at all on them and they stay sharp better than a new expensive knife.
My opinion about steels are that there is very few "home chefs" who actually knows how to use them correctly and even highly professional chefs struggles with it. The experts are butchers and staff on fishing industries. I am now very generalistic so take no offence if you actually master this.

A SJ stone cannot make a knife dull. There is no logic in this statement.

In general, sharpening has 3 variables that needs to be considered.

1. Quality of steel on the tool being sharpened
2. Correct angle for what the tool/knife is being used for
3. A sharpening system that don't burn the edge and is consistent at getting the same angles time after time.

If a customer complains that the knife gets dull after a short while, I would have a look at the quality of steel and what angle I had put on the knife. Then ask what he or she is using the knife for so I could adjust the angle so the knife would stay sharp longer.

I am a happy hobby knife collector and have knifes in the range between $30-$500 and have to many of them. I don't put the same angle on all of them, some have harder steel and some softer so I have found what works best for us in my family. We keep our knifes in a special knife draw and handwash them every time they are used. Except my Mora kitchen knifes which I am long time testing with our dishwasher, 5 year and on going and they are still in great shape.

So when it comes to taking care of the knifes, there will be differences how long a knife will stay sharp.

Our Forum member Magnus told me a story some years ago which I found very good.

A customer who bought two expensive kitchen knifes, same model,  for his daughters for Christmas called him up and made a complaint for one of the knifes. He wanted a new on warranty because one was so dull he could hardly use it. Ha had been visiting both daughters after Christmas and found two different knifes when using them.
Magnus who are an expert in knifes asked him some questions and they found that one of the daughters was very good at keeping order in the house and taking care of things and the other daughter had completely the way around and washed the knifes in the dishwasher and had no feeling of taking care of her stuff. The father came to the conclusion that it had always been that way and said politely that there was not anything wrong with the knife, it was how it was handled.

Many times when I answer questions about our product and that there is a opinion that something is wrong, the user have not had the idea to check the quality of tools they are using. I have had jigs sent to Sweden and measured them and found them to be ok, then contacted the customer and we have discovered that the tool has been bent, burned or have metal that is way to soft (cheap tools) so therefore they have had problems getting the tools sharp or in shape.

My short answer would be : Please check the quality of the steel so you can set up an angle that will keep the knife sharp as long as possible and give the customer some advice how to take care of the knifes.

Best,
Stig

[cbwx34]

Hi,
I don't agree at all.
If a knife get dull to quickly it's more likely that there was to much burr left on it. To then use a steel on it, if you don't know how to use it, will get it even worse.

I sharpen my knifes at home 1-2 times a year and I use the honingwheel 3-4 times to keep them in shape. There is no burr at all on them and they stay sharp better than a new expensive knife.
My opinion about steels are that there is very few "home chefs" who actually knows how to use them correctly and even highly professional chefs struggles with it. The experts are butchers and staff on fishing industries. I am now very generalistic so take no offence if you actually master this.

A SJ stone cannot make a knife dull. There is no logic in this statement.

In general, sharpening has 3 variables that needs to be considered.

1. Quality of steel on the tool being sharpened
2. Correct angle for what the tool/knife is being used for
3. A sharpening system that don't burn the edge and is consistent at getting the same angles time after time.

If a customer complains that the knife gets dull after a short while, I would have a look at the quality of steel and what angle I had put on the knife. Then ask what he or she is using the knife for so I could adjust the angle so the knife would stay sharp longer.

I am a happy hobby knife collector and have knifes in the range between $30-$500 and have to many of them. I don't put the same angle on all of them, some have harder steel and some softer so I have found what works best for us in my family. We keep our knifes in a special knife draw and handwash them every time they are used. Except my Mora kitchen knifes which I am long time testing with our dishwasher, 5 year and on going and they are still in great shape.

So when it comes to taking care of the knifes, there will be differences how long a knife will stay sharp.

Our Forum member Magnus told me a story some years ago which I found very good.

A customer who bought two expensive kitchen knifes, same model,  for his daughters for Christmas called him up and made a complaint for one of the knifes. He wanted a new on warranty because one was so dull he could hardly use it. Ha had been visiting both daughters after Christmas and found two different knifes when using them.
Magnus who are an expert in knifes asked him some questions and they found that one of the daughters was very good at keeping order in the house and taking care of things and the other daughter had completely the way around and washed the knifes in the dishwasher and had no feeling of taking care of her stuff. The father came to the conclusion that it had always been that way and said politely that there was not anything wrong with the knife, it was how it was handled.

Many times when I answer questions about our product and that there is a opinion that something is wrong, the user have not had the idea to check the quality of tools they are using. I have had jigs sent to Sweden and measured them and found them to be ok, then contacted the customer and we have discovered that the tool has been bent, burned or have metal that is way to soft (cheap tools) so therefore they have had problems getting the tools sharp or in shape.

My short answer would be : Please check the quality of the steel so you can set up an angle that will keep the knife sharp as long as possible and give the customer some advice how to take care of the knifes.

Best,
Stig

Good post.  I don't disagree with it.  The burr issue is one I addressed in another thread.  I do think, however, there's a bit more to add.

To your "3 variables" of sharpening, I would add a 4th...  how the customer uses the knife.  While you can make some effort to educate the user, for the most part, especially in a commercial sharpening environment, where you may never even meet the user, you have to sharpen based on use/abuse.

You might have indirectly hit on it in your example from Magnus.  Imagine if the daughter who received the "bad" knife, had been given a knife with a coarse edge that basically sawed thru whatever she wanted to cut.  She probably would have been perfectly content, and if noone came along to demonstrate the difference between a coarse and refined edge, would never know the difference.  The coarse edge will "hold up" to abuse longer.

I agree with your use of the honing wheel, provided it is properly used.  If used incorrectly, it can "dull" an edge (which many translate to the edge was "rounded" or "will no longer cut").  It's easier in this case, to eliminate the honing wheel, and use a method that is more forgiving for the sharpener, and/or leave an edge with a bit more "tooth".  (It's also why I usually recommend not to "overuse" it... especially when learning, use it just enough to remove the burr).

I use to get involved in the "coarse vs. fine" or "toothy" edge debate... for the most part now I avoid it, once I learned that how the user makes cuts, and/or their "expectations" of what "sharp" is... influences this (probably more than any other factor), and you really can't change the perception over the internet.  (I do think a 150g edge is a bit of a stretch though, but will leave it at that). 

Totally agree with your statement about the SJ stone.  (I was actually going to recommend it over the honing wheel, but knew he was already having issues with it).

Glad you chimed in (you should more often).

[Stickan]

cbwx34,
I agree on the honingpart. In the handbook there is a picture of how to hone planeblades freehand. Same technique for knives so there is a chans for everyone to do it correctly.
And also your suggested part 4, if you are in a business with sharpening. I have done numerous demos sharpening knifes and since I don't know how they are taking care of their knifes, I go a little safe and ad some degrees so they have a sharp knife that would for me personally feel a little "stubby", still sharp though.
When I first started at Tormek I thought that knifes would be the easiest thing to sharpen. I was wrong. It took me only some knifes to get it sharp but to get a knife to look factory sharpened with a nice consistence edgeline and tip, with the correct curve, that took me a while. I have sharpened some thousand knifes over the years and feel pretty confident with it.
I must admit that I went "all in" earlier with the SJ stone and different angles on different material. These days, for me, I get a very good result with the regular stone and the honingwheel.
Its good enough. I do sometimes take the time to do some knifes with the SJ stone, not because I find it necessary but because I find it relaxing doing it.

Best,
Stig

[Sharpco]

Hi,
I don't agree at all.
If a knife get dull to quickly it's more likely that there was to much burr left on it. To then use a steel on it, if you don't know how to use it, will get it even worse.

I sharpen my knifes at home 1-2 times a year and I use the honingwheel 3-4 times to keep them in shape. There is no burr at all on them and they stay sharp better than a new expensive knife.
My opinion about steels are that there is very few "home chefs" who actually knows how to use them correctly and even highly professional chefs struggles with it. The experts are butchers and staff on fishing industries. I am now very generalistic so take no offence if you actually master this.

A SJ stone cannot make a knife dull. There is no logic in this statement.

In general, sharpening has 3 variables that needs to be considered.

1. Quality of steel on the tool being sharpened
2. Correct angle for what the tool/knife is being used for
3. A sharpening system that don't burn the edge and is consistent at getting the same angles time after time.

If a customer complains that the knife gets dull after a short while, I would have a look at the quality of steel and what angle I had put on the knife. Then ask what he or she is using the knife for so I could adjust the angle so the knife would stay sharp longer.

I am a happy hobby knife collector and have knifes in the range between $30-$500 and have to many of them. I don't put the same angle on all of them, some have harder steel and some softer so I have found what works best for us in my family. We keep our knifes in a special knife draw and handwash them every time they are used. Except my Mora kitchen knifes which I am long time testing with our dishwasher, 5 year and on going and they are still in great shape.

So when it comes to taking care of the knifes, there will be differences how long a knife will stay sharp.

Our Forum member Magnus told me a story some years ago which I found very good.

A customer who bought two expensive kitchen knifes, same model,  for his daughters for Christmas called him up and made a complaint for one of the knifes. He wanted a new on warranty because one was so dull he could hardly use it. Ha had been visiting both daughters after Christmas and found two different knifes when using them.
Magnus who are an expert in knifes asked him some questions and they found that one of the daughters was very good at keeping order in the house and taking care of things and the other daughter had completely the way around and washed the knifes in the dishwasher and had no feeling of taking care of her stuff. The father came to the conclusion that it had always been that way and said politely that there was not anything wrong with the knife, it was how it was handled.

Many times when I answer questions about our product and that there is a opinion that something is wrong, the user have not had the idea to check the quality of tools they are using. I have had jigs sent to Sweden and measured them and found them to be ok, then contacted the customer and we have discovered that the tool has been bent, burned or have metal that is way to soft (cheap tools) so therefore they have had problems getting the tools sharp or in shape.

My short answer would be : Please check the quality of the steel so you can set up an angle that will keep the knife sharp as long as possible and give the customer some advice how to take care of the knifes.

Best,
Stig

Thank you for your reply, Stig. 

Since I've been using SJ, a lot of customers have claimed that the knife quickly gets dull. But after I received the knife and checked it, it was still able to cut the paper. But this is a knife to cut food, not paper.

I thought about it. Why? And I searched on the internet and here on the forum and concluded that the reason was that SJ removed the knife teeth too effectively.

The knife sharpened by SJ showed the same result even after finishing with the honing wheel.(Honing wheel will not make teeth on the knife)

As you know, kitchen knives are more often used for slice cuts than push cuts. So I think teeth are very important in knives. Some tests have also shown that proper teeth can help edge retention.

Is the reason that the knife quickly dulled is burr not properly removed? But I used SJ. I think SJ is a stone that effectively removes the burr.

I want to ask you a question. Are there any problems with edge retention in cutting food with a knife sharpened with SJ?

[Ken S]

One of the things I find fascinating about sharpening is the variety of methods used by experienced sharpeners. My favorite Mark Twain quote comes to mind, " Man is the only animal with the one true religion, all seven of them."

I have had the good fortune of meeting Stig several times, including two dinners which afforded us a good measure of enjoyable conversation time. What he wrote in his post is exactly what he says. He is not only very knowledgeable about knives and sharpening, he knows numerous experts in the field like Magnus. He also has a love for knives and sharpening, which shows. I regard him and his expertise highly. I consider him and Steve Bottorff two of the seven true religions, and perhaps not the only true religions on the forum. (For the record, I am not one of them.)

So many members ask one question and then disappear. This is unfortunate. I joined the forum in 2009 and continue to learn much.

Keep asking questions and keep learning.

Ken

[Ken S]

Sharpco,

I did not mean to ignore your last post. It came in while I was typing.

Good questions.

Ken

[Sharpco]

One of the things I find fascinating about sharpening is the variety of methods used by experienced sharpeners. My favorite Mark Twain quote comes to mind, " Man is the only animal with the one true religion, all seven of them."

I have had the good fortune of meeting Stig several times, including two dinners which afforded us a good measure of enjoyable conversation time. What he wrote in his post is exactly what he says. He is not only very knowledgeable about knives and sharpening, he knows numerous experts in the field like Magnus. He also has a love for knives and sharpening, which shows. I regard him and his expertise highly. I consider him and Steve Bottorff two of the seven true religions, and perhaps not the only true religions on the forum. (For the record, I am not one of them.)

So many members ask one question and then disappear. This is unfortunate. I joined the forum in 2009 and continue to learn much.

Keep asking questions and keep learning.

Ken

You are absolutely right. Ken.

Anyone can buy musical instruments, but great music is only possible through great performers.

Likewise, the tormek is a great sharpener, but the results depend on user's abilities.

I wanted to be a good expert sharpener and so I came into this forum. I need your help.

thank you very much.

[Ken S]

Sharpco,

I have found that I learn best when I concentrate on just one thing. That's why my chisel idea has been so beneficial for me; it makes things as simple as possible. Through frustration, I finally mastered the TT-50 Truing Tool. I consider it an essential Tormek skill. I suspect many of us put off really learning it, or even using it at all. I was that way. I think I am almost where I need to be with the stone grader. The leather honing wheel is coming along well. The real secret of learning is focused practice.

When learning to sharpen any tool, begin with a size which fits well. The Tormek knife jig is very comfortable with an eight inch chef's knife or a six inch slicer. Help yourself by learning on tools which fit naturally on your Tormek. Once you become skilled, larger or smaller knives become easy to with with.

Several years ago we had a frustrated member who had difficulty sharpening chisels. He insisted on beginning with the small quarter inch chisel, a very difficult tool to sharpen. If he had begun with three quarter inch chisels and eventually reached the small tools, he would have been fine. The Tormek can sharpen a wide variety of tools, however, some are easier than others. Learn with the easier tools whenever possible.

You mentioned the large number of scissors you sharpen. What an excellent learning opportunity! If possible, I would try to sort them and do all the like ones together. Repitition is a great learning technique, especially if we keep our mind focused.

One of my father's favorite sayings was, 'We can be bold in doing something if we are first humble in learning it." You and I share a common desire for depth in learning. I am always learning from forum members, both old and new. I hope that never changes.

Ken

[grepper]

Mr. sharpco,  I agree with you on one point.  If a toothy edge is what you are going for, a 4,000 grit abrasive won't get you there and honing with compound will remove tooth.  The SJ will produce a beautiful polished edge.  Great for chisels and woodworking tools, but, at least in my humble experience, a toothy edge will last longer for things like cutting tomato skin.  With almost any amount of rolling of the edge, a polished edge will ride on the skin of a tomato, while a toothy edge will continue to break the skin. 

You know, play with it yourself.  Grind a toothy edge and carefully deburr so as not to remove the "toothy".  Grind a smooth edge and then compare how each cuts a tomato after chopping up some potatoes.  You may well arrive at a totally different conclusion that I suggest.  Nothing wrong with that!

I think the most important thing is to actually take the time to run the experiments yourself, and form your own conclusions based on your own findings.  If you don't do that, you are at the mercy of the opinions of others, and in the knife sharpening world that can be very confusing!

A microscope can be very informative.  If a blade just rides on the skin of a tomato, you can actually check out the edge and see why.  It won't answer all questions, but it's not a bad tool to have in your tool box. 

Your customers are providing you with valuable feedback.  You have a unique advantage insofar as your customers are running tests for you!  How cool is that?  Experiment with different edge finishes, bevel angles and the like and see what works.  That would be some real world, empirical data that most folks don't have access to.  Personally, I'd love to hear what you discover!