CHOOSING A KNIFE
Identifying the Tasks the Knife will Perform
Most of the tasks in a kitchen involve breaking down soft vegetables and boneless meats. Cutting motions doing these tasks range from rock chopping to push cutting to slicing to chopping. None of these motions is better than the other, though everyone will favor one of these motions over another.
Knives can be tailored to a certain cutting style by modifying their profile. The profile of a knife is the shape of the knife while looking at the blade from the side. Just like the profile of a person. Knives with more belly/curve do better as rock choppers while knives with a fairly flat profile do well with slicing and push cutting.
Other tasks in the kitchen include cutting or peeling fruits and vegetables in hand. This is typically done with a paring knife. Paring knives have much shorter blades, giving them more control in the hand. Some chefs even use paring knives for breaking down chickens, as a short thin blade easily fits between joints.
Serrated knives usually do well with hard crusty breads
Slicing large roasts is done better with long thin blades, as they create less drag moving through the meat.
Cleavers are meant to break hard bone, and crush. Being thicker behind the edge, and often with larger angles used in sharpening. Cleavers do great at being abused, but don't do well with fine cuts.
Part of identifying what tasks one will be performing in the kitchen, is knowing how the knife will be used. Will the knife be hitting the cutting board with force, or does the user use lighter, more gentle cuts. One must also think about the surfaces the knife will come in contact with during use.
Mainly, when deciding what tasks are going to be performed, it's nice to know what shape feels good in your own hand, and knowing how you're going to use the knife. Most tasks can be performed with a single knife, which is why most professionals will try and persuade you from purchasing a set.
Ergonomics - What Handle is Best for You
There are handle shapes and sizes of all sorts. Don't listen to someone telling you one shape is better than another. The only person you should listen to is yourself when actually holding the knife in your hand.
For more experienced users, those that have handled many different types of handles and knives, one can start to know whether a handle will feel good by site. But, nothing compares to holding a knife in your hand.
Western handles are usually contoured, and shaped to be held comfortably in a hammer grip. This doesn't mean that one can't hold the knife in a pinch grip, but also allows a firm grip while holding the knife just by the handle.
Traditional Japanese handles, or "wa" handles, are typically tapered octagons or d-shaped. These handles are mainly used for balance, and offer a range of hand positions with the same grip.
Beyond shape, the texture of a handle can also play a large role in how the knife feels in hand. Some may like a polished handle, as it feels like it disappears in hand, while others may hate a polished handle because it feels slick. Those that prefer texture in their handles often lean towards molded plastics, untreated woods, and burnt woods. These textures help users feel confident in their grip, and not feel like the knife will slip out of their hands. It isn't for everyone though, as textured handles can lead to blisters and hot spots on the hand during long hours of use.
Mainly, hold a knife in your hand. If you can try multiple handles to see how they feel, then go for it. More knowledge gives you better feedback for making a choice that will better suit your needs.
Important Properties and Tradeoffs
To really understand knives, we need to first talk about steel. Steel is iron with added carbon . Typically, high carbon steel for knives has between .6-1.45% carbon per mass. Other elements can be added to give the steel slightly different properties, but what makes a steel is the added carbon to iron.
Even the same steel can have different properties based off of how it is heat treated. The process of heat treating steel can be explained in simplest terms of heating the steel to a critical temperature, and then cooling it rapidly. This process hardens the steel, and then further steps are taken to reduce hardness to give extra toughness to the blade. Each steel has a maximum hardness, at which it is not very tough (very brittle).
Hardness vs. Toughness
High hardness knives are able to hold an edge longer than even the same steel at a lower hardness. The higher hardness also allows for thinner grinds, allowing the knives to cut with much less force. The downside to high hardness is less toughness. Higher hardness knives have a tendency to break, rather than bend when encountering extreme forces.
Toughness in a steel means that it is less likely to break under extreme conditions, but will bend instead. Too soft, and the steel can fold over with too thin an edge. This can be remedied with a honing rod, which straightens the steel. However, a steel with a lower hardness will lose its edge faster than the same steel at a higher hardness.
If a knife is going to be used heavily, and come into contact with harder materials, then it's best to lean towards a tougher steel. If a knife is only going to tough softer product, i.e. vegetables and boneless meat, as well as be used more delicately, then it's better to pick a harder steel. This allows for a thinner grind that cuts much more easily, also producing a knife edge that lasts longer. Both knives will need to be maintained, but how they are going to be used, and what they are going to be used on are drastically different. There's no, "one magic knife" that does everything well.
Edge Holding vs. Ease of Sharpening
The two largest factors for edge holding, given the edge is the same thickness, are steel hardness, and the type and quantity of carbides in the steel. The harder the steel, the longer the edge is going to last. Carbides are formed with different elements, and some of them are harder than others.
The main take away, is that the longer an edge lasts, the harder it will be to sharpen. What is more important to you?
Carbon vs. Stainless
Carbon is a generic term for a non stainless blade. Carbon steel knives rust much faster than stainless, and also react with foods. The reaction with food can discolor the food, and it also discolors the steel with what is known as a patina. A patina, after sufficiently built up, will help protect a knife from rusting and discoloring food. Still, a carbon knife takes more time and care to insure it doesn't rust. While honestly, even stainless knives should be treated in the same manner, it is one of the choices one must consider when buying a knife. In most instances, a carbon knife will also sharpen more easily than a stainless knife.
Stainless is the generic term for a steel that is resistant to reacting with water and acids. Stainless knives can still rust if left wet for a long time, but it is less critical to baby them around water. Stainless knives will not discolor food either, as there is no patina building up on the surface. The chromium content in a steel is what defines a steel as stainless or not, and there is a range of how stainless a knife can be. There's a difference between a kitchen knife, and a knife being used at sea in salt water. So while stainless is easier to care for in a kitchen, since you don't necessarily have to keep it bone dry, it will take longer to sharpen, as chromium carbides are harder than carbides present in simple steels.
I'd recommend casual users to get stainless, as it takes away one more thing to worry about. Also, you have connections with a professional sharpener who can sharpen either one ;).
Heavy vs. Light
We all have different preferences when it comes to length and weight of knives. Long vs. short and heavy vs. light are neither right nor wrong, but based off of what feels good to the user. If you want a lighter blade that feels like nothing in hand, then go for it. But if you want something that feels substantial in your hand, then get something a little heavier. Lighter knives will usually require a little more force to cut through food, but may not fatigue the hand as much as a heavier knife that must be lifted over and over again. Whereas, a heavy knife will fall through food much more easily, but requires one to lift that weight to make the next cut. In all, it's important to feel knives in hand and make your own judgment, rather than relying on someone else's opinion.
Cutting Ease vs. Food Release
The thinner a knife is behind its edge, the easier it will cut. However, make a knife too thin, and the user may experience troubles with foods sticking to the blade. If you've ever had a potato stick to the side of the blade, and feel like it was glued on, you'll know what I mean.
On the opposite side, have a knife too thick, and while foods may not stick to the side of the blade, you may find harder produce like carrots and potatoes breaking apart, rather than being cut.
There's often a good balance between cutting ability and food release, but ask yourself what's more important to you. Most makers will specialize in one direction, so finding a maker that can create what you want should be your main concern.
The amount of time that it takes to make a knife will be a large factor in its total cost. Making knives in bunches, or taking as little time to complete a part of the production can dramatically reduce the cost. Knives that cost as little as $11 are usually made with the least amount of time possible, relying on machinery to complete a large majority of the work. Companies also can have machinery run multiple knives at the same time, increases production capacity.
On the other hand, making a blade by hand can take a lot of time. Depending on the level of fit and finish, the number of people working on the knife, as well as the complexity of the build, a handmade knife can take weeks to complete.
Just like making knives, the time that goes into making steel ultimately decides the price. Mass produced steel is relatively cheap, and smaller and smaller runs of different steels cost more and more. Further, more can be done with steel after it is produced to add to the cost.
Machines are expensive, but have the ability to be very fast and consistent at performing the same tasks over and over again. The downside, machines don't respond well to change. Each new type of knife takes a complete design before it can be started. This locks companies into very few designs, built for the average.
There are different levels of handmade. One is like a production line, where there are multiple people involved in producing a knife. An example of this can be seen in quite a few handmade Japanese knives. Where there will be one forger, a number of grinders/sharpeners, handles made by someone else, and a different person that assembles the knives. Shops like this can produce quite a few knives as compared to a single maker. The downside to this approach, is that often there will be a lack of consistency between knives.
One the other hand, single makers usually focus on every aspect of the knife from start to finish. Much more time consuming, but quality control is usually much more exhaustive, as one person was involved from start to finish. The ability to customize a knife to exact standards is much more realistic in this situation, but comes at a premium price.