Toothy vs Polished Edge

[grepper]

I had learned, and intuitively it makes sense to me that a polished edge would have better edge retention than a toothy edge.   Fairly recently I was wandering around the ‘Net and saw some stuff saying that due to the way a toothy edge wears, that a toothy edge could have better edge retention than a polished edge. 
 
At this point I have no idea where I saw that info, but it ran contrary to my understanding.  I have always thought that a toothy edge was less stable because the peaks of the “teeth” were not well laterally supported.
 
What’s the real story?

[Ken S]

Grepper,

I was sitting in the dentist lobby below one of the too many television sets. I normally tune it out, however, the program was Ina Garten, the Barefoot Contessa, a cooking show. Ina made something with folded dough. She recommended cutting it with a sawing motion to avoid crushing the dough. 

Smooth or toothy? I believe a skilled sharpener should be sensitive to the intended use of the knife or knives. Just as a wood worker uses both chisels and saws, a chef should have different knives optimized for different cutting functions.

My ceramic "steel" adds nice tooth.

Ken

[Ankerson]

I had learned, and intuitively it makes sense to me that a polished edge would have better edge retention than a toothy edge.   Fairly recently I was wandering around the ‘Net and saw some stuff saying that due to the way a toothy edge wears, that a toothy edge could have better edge retention than a polished edge. 
 
At this point I have no idea where I saw that info, but it ran contrary to my understanding.  I have always thought that a toothy edge was less stable because the peaks of the “teeth” were not well laterally supported.
 
What’s the real story?

For knife blades in general toothy will give better edge retention overall. For other tools such as wood working tools I really don't know for sure, likely something balanced in the mid range.

[Bobbo]

Would someone mind explaining what you mean by smooth, polished or toothy edges? How do you create these edges?

[Ankerson]

In general it comes down to what grit the edges are sharpened and or micron level.

The finer the stone used to sharpen with the smoother or more polished the edge will be.

[grepper]

In general it comes down to what grit the edges are sharpened and or micron level.

The finer the stone used to sharpen with the smoother or more polished the edge will be.

Bobbo - I'll try to explain a bit more, as best I can, what he is talking about.

One way to consider it is that sharpening a blade is a lot like sanding a piece of wood with sandpaper.  If you have a very coarse (low grit number) sandpaper it will leave a very rough, scratched surface.  You can actually feel the roughness with your fingers.  But if you keep sanding with finer and finer (higher grit number) sandpaper, as you sand away the deeper scratches, the surface becomes very smooth ready for painting.

The exact same thing happens when sharpening a blade with some abrasive.

Here is a microscope image I took of the bevel of a blade that I sharpened with, if memory serves correctly, a brand new, 400 grit belt on my belt grinder.  A brand new belt can be pretty rough until you have used it a bit.  You can see the scratches created by the rough, basically sandpaper in belt form, belt. 

If you look carefully and/or zoom in on the image, you can see how the scratches go all the way to the edge.  These scratches cause the edge to have, for lack of a better term, little "teeth", like a saw blade.  Hence the term, "toothy edge".

These images are "thumbnails".  Click on them to view a larger image.

   

Now, compare that to this blade I sharpened with a very fine abrasive.  It is much more smooth and polished and therefore not "toothy".  Hence "polished" edge.

   

You can see how a toothy edge is sort of like a serrated knife blade only on a very small scale.  A toothy edge is generally better for slicing things like tomato skin than a smooth, polished edge is because the tiny "teeth" grab the skin rather than just riding on the surface.  For kitchen knives, a toothy edge is generally more useful than a very smooth, polished edge.

Hope that helps!  Ask away if you have any more questions!

[Bobbo]

Thank you very much Mr.'s Ankerson and grepper! I find this all very fascinating. I thought a sharpened edge was simply a sharpened edge until now. I've done a little more reading based on your comments. Apparently a smooth and polished edge are pretty much the same term for the same thing so the choices are toothy or polished and degrees thereof. Apparently a toothy edge might be great for carving up a rib roast but you wouldn't want to shave with a toothy edge.

It is becoming obvious to me that I need to upgrade my edge grinding capabilities to something beyond my electric sharpener. Would you gentlemen have a suggestion for me in consideration of my current skill level? Please don't suggest a sharpening stone. I bought one of those and my edge tester proves that I don't know what I'm doing. I hate to impose on you again and thank you very much for your help.

I don't mind spending a few hundred dollars for the right stuff especially since I have, apparently, wasted $150 on this glorified version of a mad bumblebee electric sharpener. I'm willing to pay more if a good result is pretty much guaranteed.

[Ankerson]

Thank you very much Mr.'s Ankerson and grepper! I find this all very fascinating. I thought a sharpened edge was simply a sharpened edge until now. I've done a little more reading based on your comments. Apparently a smooth and polished edge are pretty much the same term for the same thing so the choices are toothy or polished and degrees thereof. Apparently a toothy edge might be great for carving up a rib roast but you wouldn't want to shave with a toothy edge.

It is becoming obvious to me that I need to upgrade my edge grinding capabilities to something beyond my electric sharpener. Would you gentlemen have a suggestion for me in consideration of my current skill level? Please don't suggest a sharpening stone. I bought one of those and my edge tester proves that I don't know what I'm doing. I hate to impose on you again and thank you very much for your help.

I don't mind spending a few hundred dollars for the right stuff especially since I have, apparently, wasted $150 on this glorified version of a mad bumblebee electric sharpener. I'm willing to pay more if a good result is pretty much guaranteed.

I would recommend getting a Spyderco Sharpmaker to start with and see how that works out for you.

Then later on if you choose move up to one of the Guided systems like the Edge Pro or Wicked Edge, I use the Edge Pro.

[grepper]

Bobbo-

What electric sharpener do you have?  Before you get another sharpening system, I'd be curious to learn what you are currently using.  It may be just fine for your purposes and is just a matter of understanding how to use it correctly.

That said, if you want something else:

The Sharpmaker mentioned above is kind of like using a stone except that it's easier to get a consistent bevel angle.  With a stone you hold the knife at some angle as you move it over the stone.  This can be difficult because until you get a lot of practice it can be difficult to maintain a consistent angle.  With the Sharpmaker you hold the knife vertically and the "stone" is at an angle.  It's much easier to hold a blade vertically than it is to hold it a a consistent angel.

The Edge Pro and other guided sharpening systems are easier for the beginner because both the knife and stone are held in at a fixed angle to each other.  They also produce excellent results with perfect bevel angles every time with no guess work. Many professionals use and swear by the Edge Pro.  If I were going the manual route, I'd probably get the Edge Pro too.  I'm not recommending it, that would only be a personal preference.  With any knife sharpening system it's a matter of personal preference.  There is no right or wrong answer.

There are lots of YouTube videos.  Spend a little time researching to see how the different systems work and what appeals to you.

Another guided system is the Tormek T-8.  It's a great system, but starting @ $700.00 it may be overkill for what you are doing and more than you wish to spend.  Onion other hand, if you are a woodworker the Tormek has real advantages.  I have a Tormek.

Another option is belt grinders.  They work very well and have the advantage of being much faster then manual systems especially if the blade is dull and you have to remove a  bunch of metal.  Another advantage of belt grinders is that belts are inexpensive, available in just about any grit you wish and you can change belts in less than a minute.  Depending on the belt grinder you use you may need to fashion some sort of a knife rest if you don't want to free hand it.  When I want to use a belt grinder to sharpen, I use a Kalamazoo 1SM, 1" belt grinder with a home made knife rest.  Here is a picture of it.  The 1SM grinder is about $270.00 delivered and then you have to come up with some sort of knife rest.  I've used this for years and have been very happy with it.  Here is a picture of mine:

   


Another option in the belt world with a built in knife rest is the Work Sharp Ken Onion Knife Sharpener.  At $130 it's a more affordable, smaller and very portable option.  I have the less capable WSKTS model, and it can get blades very sharp, very quickly.  But if I were going to get another I'd go for the Onion model because it has an adjustable knife rest.  This might not be a bad way to go for a starter belt grinder.  I have not used the Onion model, but I'm guessing it works well and it gets good reviews.

If I was just starting out and wanted the manual method, I'd probably go with the Edge Pro.  For a starter belt grinder I'd go the the Kzoo 1SM or possibly try the Work Sharp.  The 1SM is handy to use as a general purpose grinder too, but as I said, unless you want to freehand sharpen you will need a knife rest.

Don't rush to make a decision.  Do your research.  Watch YouTube videos.  Try to get a good handle on what it all means.  We have only mentioned a couple of choices.  There are lots of different ones.

I know this is all pretty confusing.  Been there, done that!  I've wasted lots of money!  Everybody is a beginner at some point, and nobody is an expert at everything.  There is a lot to learn but that's why we are here.

Hope that helps!  If you have further questions please feel free to ask away!

[MaxtheKnife]

i am new here and mr rupert told me about this new forum, so i going to jump right in here.  i am new to sharpening knives compared to many here, but since 2012 i have worked farmers markets, local gun shows, whole foods, williams-sonoma and other locations from time to time.

i sharpen kitchen knives - pockets - hunting/fishing - fabric/household scissors and lot of yard gear.

started with edge pro in 2012 in may....july moved to wicked edge - only worked farmers market then....2013 business started to pick up and after most sat. mkts. i had homework.......i soon bought a HF 1x30 belt sander and pre sharpened all homework knives and then to WE.......the WE and EP both do great on knives...especially kitchen.

these days i used 4 belt sanders.....3 kelly's and 1 viel, 2 of which are variable speed and i used the WE as well, but i charge 20 bucks or more per knife for WE.........i have several restaurant accounts that i do, some i rent and replace every three weeks on the average.

also in my area of virginia, the coast in va beach, there is a greek family that sharpen knives for 80 years for restaurants and cover 3 surrounding states...big outfit........2 to 3 bucks per knife and replace weekly.

restaurants cut so many different things it is hard to sharpen all so they cut this and that......the WE makes a great restaurant edge after the 1200 grit paddles followed by ceramics........but slow, but they cut tomatoes.........restaurants LIKE KNIVES THAT CUT TOMATOES.  with my belt sanders i use to go up to 1200 grit trizacts and polish.......cut great.....celery, carrots...etc.....TOMATOES.....GO LUCK

Since 2012 i have made some good friends in the knife world and they have helped me through many questions and all sorts of things that i was not a rocket scientist with.........I'd like to thank all of you for the help......mark reich, rupert lucius, ken schwartz, james ammons, don daily, and two of my knife buddies....peter woolworth in ca  and a new guy named garry in tx...........THANK YOU.

the big commercial guys knives appear to be sharpened on a stone.....real toothy and they cut tomatoes  much nicer than the polished jobs i did.....they would call me up the next day and say....hey these knives will not cut our tomatoes.......i called some of the guys above and now at 73 years old my knives will cut tomatoes .......still using kallys...1 x 42"........80grit to 220/240   a few around 600, but 95% of the restaurant knives i stop at trizact A65..........i finish on leather........felt......compounds............i really have fallen in love with 3m non-woven belts......scotbrites.......maroon is med.......blue is fine and  gray are super fine.........they love serrated blades, mowers, axes, yard stuff.

i am reading and listening right now.......please comment

i am going to ask my three buddies to stop by.....peter.....garry and jeremy