A closer look at sharp.

A sharp knife that leaves a smooth surface after a cut is essential for carving. I have been having a look at some of my edges with 40x magnification to get a better understanding of the meaning of "sharp", and thought I`d share my findings. 

Lets begin with the edge of my Victorinox Huntsman. This knife is in my pocket/backpack everyday and is put to regular use. It passes my paper-test, but it is not shaving sharp at the moment. The paper-test for me is as follows: Does the knife smoothly slices through a standard sheet of A4 paper that is losely held at the corner? If the answer is no, then I consider the knife blunt. I have to say I was surprised to see the state of this edge: 

Victorinox huntsman

Sections of the edge are quite ragged, and there are grooves and nicks in the bevel. Having seen this I have to say that it cuts better than I should have expected by the looks of it, but perhaps it is more like sawing then cutting at some places. Compared to my Opinel #8 it is quite a mess.   

Opinel #8

Here is an image of the edge of my Opinel at 40x magnification. I once reset the secondary bevel of this blade to 17 degrees, and have since then only maintained it with a strop. I am a little more careful with this edge than with the Victorinox one (i.e. I do not scrape with it and do not cut where there is a high risk of hitting metal/stone etc) but I have certainly not shied away from using it. I am very fond of the friendly appearance of the Opinel and therefore I often have it on me. It regularly cuts boxes, fruits and vegs, wood, tape, rope and all other things one cuts on a daily basis. I`ve had it for more than two years now, and am seriously impressed with how it keeps up! Especially for the price. Anyhow, as you can probably guess from the image, this blade is seriously sharp. It shaves with ease and currently puts my SAK to shame.

I am a bit reluctant to show the next one, as it shows what a poor job I have done in sharpening the EKA folder. The Lansky-kit I have has 5 different grids, and to reprofile this blade I started on the coarsest one. Then either in the step from coarsest to the next, or the step after that, I have not been thorough enough in grinding out the grooves of the previous stone. This results in this bevel that is relatively smooth, but ploughed through with deep grooves left by one of the coarser stones. At the edge this produces the effect of tiny saw-teeth. The knife will cut well, and feel sharp, but it will not last long and it most certainly is not a pretty sight to me. Needless to say I want to redo this one soon. 

EKA swede 10

On to two of my carving knives. First I`ll show the edge of one of my Mora 120s, because it has something interesting going on. If you look at the bevel here, you see that toward the edge it gets smoother and the angle of lightreflection changes. This is due to the fact that the bevel is slightly rounded towards the edge. This rounding is caused by my stropping the blade a lot. Initially it is not really a problem, but from time to time a rounded edge has to be set straight again on the stones, as I will do with this one. I will also spend more time on the 800 grid waterstone before moving on to 2000 and 5000. This is to get rid of the same problem I described with the EKA.

Mora 120

 The last one I  have here is the best example of sharp I had to put under the microscope. It is my Mora 711 blade that is my main carver. I use this knife all the time and keep it in good shape. There is some slight evidence of rounding, but this is far from causing a problem on this knife. The bevel is smooth and the only grooves you see are caused by the fines stone I own.

Rehandled Mora 711

 Of course sharpness of a blade is also defined by other factors like Edge Geometry and material, and not only how the bevels look. It is, however, the main factor for the sharpness of all edges. I will now not go into edge geometry, or the fact that for some cutting tasks a coarser edge is actually better. Looking at some edges in such detail increased my understanding of sharpening, and it also showed me that some of my blades need a bit of attention soon! If you want to understand your own knives better, have a look at the edge in detail. Using a microscope to achieve 40x magnification is fun, but with a small lens like this one you can already see all you need to see.