knife issues

A colleague who is seriously into cooking and is also a Baroque oboe player (and hence is used to sharp knives) told me that a professional sharpening service tuned up his kitchen knives so they became like new. Apparently they (the sharpeners) serve chefs all around the south of Sweden. This is good news. Many people don’t even seem to know what a sharp knife feels like – hopefully so. Many people don’t even seem to know what it feels like to work with a sharp knife.

Now, if you have the right equipment and some experience, sharpening a good kitchen knife so it actually becomes sharper than it was when new is really not such a big deal at all. So in part, this story is also bad news. No traditional carpenter (and ‘hand’-cooking is tradition too) would give his planes, saws and chisels away for sharpening. The assignments of a tool influence the way it has to be sharpened. The ability of a tool’s steel to keep its edge will influence the way it is used. This circular system will only yield useful practical information to those who do all of the following: choose a tool, use a tool and sharpen it. It would hence be better if someone would earn money by teaching all the chefs how to sharpen their knives.

Equipment: a bunch of Japanese water stones for grinding and honing. I have stones with 800, 4000 and 6000 grit. The stones can be kept in a closed plastic container in clean chalk-free water all the time. This is a good resource.

Grinding: It is a good idea to practice with a cheap knife, even if cheap steel never gets all the way sharp. Buy a magnifying glass (10x magnification or more) so you can see what you are doing. Prepare the edge on the 800 grit stone. A constant angle along the whole blade is easiest to achieve if one moves the knife lengthwise across the stone instead of perpendicular to the blade (as one would do with plane irons or chisels). Never cut into the stone, however, it would instantly ruin your work and the surface of the stone. Try imagining that sharpness is two planes meeting at an angle and nothing else. Keep to the angle you chose at the beginning, alternate sides and stop only when you are done, that is, when both newly ground faces extend all the way to the edge of the knife. Most Japanese kitchen knives ought to have a very flat grinding angle: I elevate my vegetable knife just enough to free the wooden handle from the surface of the stone. Western-style knives usually have somewhat steeper grinding angles. One should choose varying angles for varying tasks. A knife that is likely to be used for chopping hard goods ought to be sturdier, with a blunter angle, than a knife used for soft goods.

Honing: one method to achieve edge sturdiness is a secondary bevel. This is what most people do when honing the knife: they elevate the blade a little more and hone only the very edge of the blade. Most of the time it is okay to directly start using a 6000 or 8000 grit stone. A secondary bevel is what most of the whispering about the benefits of professional sharpening is about. It should be noted that a secondary bevel is not a requirement or a sign of a special quality treatment. A knife is well sharpened if it does its assigned job well and doesn’t get blunt after 2 minutes of use. In my Japanese knives, which in any case are too hard and brittle for cutting hard materials, I keep the single-bevel edge slim. Most of the time, I actually just touch up the edge with the 8000 grit stone, that is enough. Robin sharpens her marvellous German Chef’s knife with two bevels and it works fabulously like that.

Stropping. A barber’s strop or at least an old piece of leather belt, sized with some fine stropping paste (see the resource above) gives the ultimate finish to your edge. It also introduces, according to some, a micro-bevel that preserves the edge better. I have been a-travel using a woodworker’s knife for hours daily, cutting and scraping plastic elements. I only used the strop for keeping the blade in shape and at the end of the trip, it was still perfectly sharp.


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