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Knife Sharpening ... what am I doing wrong

11K views 78 replies 19 participants last post by  kolokotroni 
#1 ·
Ok guys so basically I have started trying to sharp my own knives.

I currently own a normal victorinox chef knife and a combined sharpening stones. I have barely any knowledge in this field and I consider this an experimental phase before I purchase better knives in the future.

Basically my issue is this, after I sharpen my knife I manage to cut through paper and slice tomatoes very thin but (this may sound disgusting to some) I usually try to shave of some hair of my arm to see if its razor sharp and I never manage, I seen this in some videos on youtube. 

For sharpening what I do is first start on the dark side then finish of on the lighter side, I do around 10min on each side. I have never tried with a different knife but I am assuming that I am doing something wrong.

Any suggestion or pointers?
 
#4 · (Edited)
Firstly understand that you have a Vic. Without too much effort it can get very sharp, to where it will easily shave [arm] hair, but because the steel is relatively soft and stainless it cannot hold that sharp for long, and actually the first few strikes on the board will wipe it away.

If you just want to impress yourself then, after you have thoroughly deburred (a fairly recent post shows Jon Broida using the best technique I know of) and the knife is sharp as you know sharp, then take a few stropping strokes per side at a time, and very lightly, a dozen or so per side total. Make your initial edge relatively acute as you will need to raise the spine a bit to be sure your stropping strokes are hitting the edge.

But be warned! This may give you the urge for a new and considerably more expensive knife. And possibly the need of bandaides.

Rick
 
#5 ·
I use an old (about 20 years) 10" vic cimeter once in a while in my kitchen.  I've carried this sword around all over the place and it always comes in handy.  I upkeep the knife the same way as you've described.  It is easy to sharpen on a double sided stone.  I've found that once sharp,  a smooth sharpening rod realigns the blade nicely with about a dozen strokes per side.  In a pinch I can run it along a medium grit diamond sharpening rod, and then back to the smooth rod for a few more strokes.  The knife is actually closer to 30 years old but sat around at my grandfather's house before I began using it (he bought it in Germany in the 80's).  I'm pretty sure that the knives are manufactured the same way as 30 years ago unless recycled steel is in the mix. These knives (I've used a bunch over a couple of decades) are easy to have rebeveled when dull and come back to life afterwards. You want an approximate 20 degree angle when sharpening on the stone with a vic knife.  Go form tip to heel back and forth while alternating sides after about 5 strokes per side.  I feel the blade on my thumb after every dozen strokes to check for the micro bevel. After you feel the toothy micro bevel is about even on both sides, sharpen it only  from tip to heel while alternating sides at each stroke until the blade starts to feel smoother to touch.  Once you feel that the blade bites evenly is when you hone it on the smooth rod.  These blades are easy to get a scalpel edge on.  I hope this helps. 
 
#6 ·
Hi Keith, I too own a victorinox and it's as they say very easy to sharpen. I just sharpened mine yesterday and it is very very sharp and the angle I'm using is about 12 degree each side. I sharpen on a 800grit ceramic stone and a fine stone I bought from a Chinese store. My sharpening technique is based on Mino Tsuchida of global knives and I can also say that the edge can last a month or two of heavy use if you're not hitting the cutting board too hard. Watch Mino Tsuchida and try to use his technique, I learned a few sharpening techniques and that is the one I prefer.
 
#7 ·
Hey guys, I checked out the videos you told me cysoon, damn that technique looks a bit hard, yes my knife cuts paper and tomatoes very thin with ease, I also asked my friend to get his knife(just like mine) which is brand new and it to cannot shave and it has a factory edge which I assume it should be good.

I will now buy a new stone as I have no idea what grit mine is and will start practicing the Mino technique.

Thanks for the help
 
#8 · (Edited)
Hey guys, I checked out the videos you told me cysoon, damn that technique looks a bit hard, yes my knife cuts paper and tomatoes very thin with ease, I also asked my friend to get his knife(just like mine) which is brand new and it to cannot shave and it has a factory edge which I assume it should be good.

I will now buy a new stone as I have no idea what grit mine is and will start practicing the Mino technique.

Thanks for the help
I suggest getting some low end knives and practice sharpening on some Chinese sharpening stones before attempting to sharpen your better knives on your better stones. It's actually very easy Keith, steady hands and keeping the right angle is all you need. Oh and make sure you use the whole surface of the stone, the way I do it is I use the middle of the stone for the belly to the heel of the knife and the sides for the top part of the knife
 
#11 ·
If it's basically sharp and cuts well but either 1) won't shave hair or 2) will only shave hair on one side of the blade then you almost certainly haven't removed all the burr.  You can do this on the stones but it generally takes more grits and/or more time, you can use felt or the end of a wood block, and often you can deburr on a ceramic hone.  A brass rod works if you're careful.  With felt you just slice through it lightly, same with wood.  On a brass rod you need to use a stropping motion.

It's best to work the burr mostly off on the stones.  As you sharpen some steel will kind of "flow" like frosting while you ice a cake. That peak of steel flowing off is called a burr.  Each time you flip the knife and work the other side the burr gets work hardened and weakens a bit.  Eventually it will peel off (and hopefully you're going light enough at this point not to create a new burr).  You don't want to rip off a big honkin' burr because you'll leave the edge somewhat jagged; it's best to refine the edge and work the burr a bit.
 
#13 ·
I don't know if anyone said it, but skimming the thread it didn't seem like it, but the first 2 posts mention something similar...


It doesn't matter if you can slice hair, or paper.  A lot of people mention that it isn't a good indicator if you do those things.  It's just something people seem to do in order to test it out, but it seems it can also KILL your edge to cut papper and such, but I don't know much, as I'm a newbie.


The real indication is if you can slice, what you intend to slice, you're golden.  If you cannot slice that tomato, that's your issue, not the arm hair.
 
#15 ·
Well, I know but I need a comparison :) its not easy to explain sharp over the internet so I just gave an example ...

Anyway I re sharpened my knife, using the method showed by Mino, I can say it much sharper now, tested it on a piece of paper and able to cut strands easily again I cant shave any hair :p I am saying this as about 4years ago I owned a 30cm Global chef knife and it was amazingly sharp but I never sharpened it so I am wondering if its the blade or my technique ... I know practice makes perfect but I need to make sure my practice is correct and not get into any bad habbits.
 
#16 ·
You better get a very good Japanese waterstone. Its difficult to sharpen any knife with a mediocre stone.

Besides a good stone will last you for years and is a good and necessary investment.
 
#17 · (Edited)
So you go buy expensive fine stones, polish up your victorinox's edge and maybe it now shaves hair.  Maybe you cut yourself or get razor burn, poetic justice for doing dumb stuff IMO.  Does that make it a better chef's knife? Cut food better? Does it last longer between sharpening? The polish won't hold on that steel, and the geometry hasn't changed.

Never tried shaving with a kitchen knife, and I never will
 
#20 ·
Flatten with something you know is flat.  Diamond plate is a metal plate coated wtih diamonds.  They come in a few different price ranges.

I use the one from japanese knife imports and it works fine.

If you flatten with something not necessarily flat, then the surfaces will at some point align to each other, but may or may not be flat.

If your stone has low spots, you'll get a convex bevel, which is not the worst, but maybe unintended depending on what you're doing.
 
#22 ·
Sharpness testing

Paper. Printer paper has clay and such to create a good surface for the ink. It can be informative, but is a bit tougher on the edge compared to other tests. There are two paper tests. A draw stroke, probably the most intuitive and common test and a push cut.

The draw stroke is particularly useful for finding flaws in your edge. As you perform the draw stroke, when you get to said flaw, the cut will often turn into a tear.  However, technique is important to consider as you use this test. Generally, people give the paper some stiffness to help them start the cut. The common method is to curve the paper in your grip a bit. The stiffer you have to make the paper to start the cut, the duller your edge. You can also do this test more horizontally or more vertically. Horizontal is easier but masks the edge quality a bit. Vertical cut is more prone to tearing out and so is more revealing. 

The push cut can be difficult to get started. It takes a fairly refined edge to push cut paper readily. The paper will usually deflect some at first. 

The paper itself matters some too. Newsprint is much more difficult to test your knife in that printer paper or magazine paper. It's more fibrous and prone to tearing. Being able to cut a free hanging piece of newsprint is tricky, but there are some technique tricks here too. mostly about coming in at a downward angle to use gravity and the edge catching the paper to stiffen it up against the grip point. A highly refined edge is important so there is no tearing. 

Clearly then, technique, paper and the edge all play into what a paper cutting test can reveal. The paper test can be used to deceive a bit  even. It's useful to examine the cut of paper too. how cleanly is it cut. Is there rolling of the edge on the cut, how feathered is the cut and so one. 

I'll post some more about the shaving test in a bit. Have to go for now. 
 
#23 ·
Shaving. As with paper, there are variables. I have very thin and fine arm hair. It will resist shaving in many cases. However, the right technique and you can shave with much less than optimal edges. Most people go flatter to the arm if it's not shaving. That just lets hair bend out of the way in my case. You have to go more vertical and scrape to shave my arm hair. Definitely no draw in the stroke, that's just asking to get cut. Shaving impresses people but isn't particularly revealing about the edge

Some printer paper test images to consider from a few years back.


This is a short paring blade, maybe an inch and a half in length, hollow ground. Really rough start and as it rounded the belly towards the tip, it went bad fast. The feathering in the clean cut is pretty clean. A little roll at the edge of the sheet but not bad.


This blade cuts printer paper quite well. Again, some flaring of the paper, but some of that is unavoidable.

Cutting a potato will tell you about the state of your knife edge. A sharp edge creates a smooth slick cut surface when you touch it. A dulling blade leaves a wet pebbly surface to the touch.
 
#24 ·


Does some angling to get maximum stroke to avoid any push cutting on the tissue. So it's pretty sharp, but he's cheating a bit.

Hair whittling. Notice that his blade edge lacks bite. The hair skates and he has to get pretty close to his fingers before it will cut.



If he had cut into it at an angle towards the end so it would bite and be in tension between the knife edge and his grip we might have seen some "better" cutting.

Some tissue paper cutting. It gets more interesting at the midpoint where he brings out a knife with some polish to the edge.



Would have been more interested in how it did free hanging or vertical
 
#25 · (Edited)
Oh Murry, you're so full of drama. I don't know that I'd care to wet shave with that knife.

Even though it's a good grade of white steel there is only so much you can do with a 6K King stone and a few swipes on news paper (which really doesn't do much more than give some shine to the edge). In another video he shows what looks like a 5oz max knife piercing a tomato skin with its own weight. He then eases the knife just over the initial cut and draws down rapidly the finger he balanced the blade on, resulting in the blade sinking about a half inch into the tomato. Granted it was a very ripe looking tomato, but most folks never had an edge that can push cut a tomato skin, at least not without squishing things considerably.



Rick
 
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