Specifically, I was interested in buying something sort of in between a small paring knife and a chef’s knife. I find my chef’s knife to be too big and clunky for working with smaller products like shallots, a bit to broad for taking apart small poultry. But my paring knife doesn’t have any knuckle clearance for chopping, so it’s not particularly useful for these tasks either.
Some chef friends recommended I consider Japanese “petty” knives, which are similar in size to Western utility knives but are thinner and lighter. In general I find I prefer Japanese knives to Western ones, so I started investigating. ChefSteps has a page mentioning some of their favorite knives, and they include a small selection of petties amongst these. But beyond a cursory and somewhat-generic description of each knife, there’s little information provided to suggest what differs one from another. What makes one petty knife cost twice as much (or more) than another? What’s the difference between damascus steel and ‘carbon’ steel (and what does that latter even mean)?
The slope grew quickly slipperier beyond this. The lower-priced damascus steel petty mentioned on ChefSteps is relatively easy to find online; the highest-priced one is not. This seemed strange; I’d always heard of damascus steel’s purported awesomeness, and had never heard of the maker of the more expensive carbon-steel blades. Some online searching for the highest-end brand (“Yoshikane”) on ChefSteps’s page intersected with forums in which members either seemed to be asking where to find one of these knives or announcing excitedly that they had nabbed one. They seemed to be almost like collectors’ items.
I started researching so-called “damascus” steel. Originally referred to as “wootz steel“, its variegated pattern (reminiscent of a flowing river) was a result of a combination of alloys and a tempering process that yielded a steel that was particularly durable and could hold its sharpness well. It was developed in South India; as word of its durability began to spread, forged ingots began to be imported to the Syrian city of Damascus, which was home to a thriving weapons industry. Bladesmiths in Damascus adopted and perfected the technique of forging this steel directly, and the reputation of the durability of Damascus steel became nearly legendary.
Unfortunately, the original method of producing this steel is now largely unknown. Differences in raw materials and the evolution of manufacturing processes have made attempts to recreate the steel mostly unsuccessful. Most “damascus” steel that’s widely available today is a bit akin to something like the ‘butter flavoring’ you might squirt onto your movie popcorn…it gets the job done, but isn’t the real thing by a long shot. Since modern folks rarely need to cut through pieces of armor, we understand the steel’s striking visual appearance more than we have a need for blade durability, and we’re generally content to leave it at that. Modern bladesmiths address this by creating steels with “Damascus patterns”: they fold together multiple steel alloys like layers of a croissant, and etch the final blade to highlight the variegated pattern. It looks similar to the wootz steel of legend, but the similarities typically end there.
I realized that understanding the true character of the original wootz steel–as well as that of this ‘carbon steel’ that I kept coming across as I was exploring this–would require some understanding of metallurgy. To try to uncover more information, I started visiting knife shops in the Bay Area. The owner of Town Cutler guided me to one of his favorite manuals for getting an introductory understanding of how steel is made. Time to put your learning pants on:
A knife blade typically begins life as iron ore, which is simply rock impregnated with enough iron to make it interesting for us to want to extract it somehow. This “somehow” is accomplished by building a very hot fire inside a large, narrow chimney which is packed with iron ore. The ore eventually melts and drips down into a large container (the “hearth”), with the rock matter (“slag”) and the molten iron settling into two different layers (like oil and water). A tap draws off the iron, which contains some unknown percentage of carbon from the rock matter. This iron (called “pig iron”) is guided into a large, flat pool lined with iron oxide. The oxygen atoms in the iron oxide lining react with the incoming carbon atoms in the pig iron, forming carbon dioxide; the pool of molten iron bubbles vigorously during this stage as the carbon dioxide gas is released, leaving behind pure iron.
To this iron, a very specific amount of carbon can be added to yield what we call “steel”. The carbon contributes greatly to the hardness/durability of this metal. Below about 0.75% carbon content, this steel is not sufficiently hard enough to take/hold a cutting edge. In the range of 0.75% to 1.5%, the steel is referred to as “high-carbon” or “tool steel”; it’s within this range that steel can be forged into a tool used for cutting: rasps, files, axes, mill/drill bits, and knives. Above 1.5% or so, the alloy becomes too brittle to be used for bladesmithing; it’s then referred to as “cast iron”.
To high-carbon steel, other metal alloys can be added (tungsten, molybdenum, vanadium, nickel, and, in the case of stainless steel, chromium) to provide various qualities that might be desired for a given steel depending on its intended use.
How does stainless steel differ from high-carbon steel when it comes to knife blades? Stainless steel gets its name from its high resistance to rust and corrosion. In terms of kitchen knives, it’s incredibly convenient; a stainless steel knife doesn’t need to be washed immediately after cutting a lemon; it can be left out dirty overnight or sent through the dishwasher without fear of overt rust damage. But stainless is also difficult to sharpen to a razor edge, and doesn’t hold its edge particularly long.
This is where carbon steel excels, and is why carbon steel tends to be the preferred material of choice for most professionals and serious home chefs, who use (and need to sharpen) their blades frequently. Carbon steel can be sharpened easily and holds its edge much longer than stainless. This excellence comes at a price, however. Carbon steel is not corrosion or rust-resistant, so it’s typically a more finicky, high-maintenance blade. There’s a learning curve for someone moving from stainless to carbon blades; the blade will tarnish in minutes if not washed and dried immediately, and it needs to be stored properly.
After absorbing some of this, I went to visit another cutlery shop in San Francisco. Bernal Cutlery stocked most of the knives mentioned on ChefSteps’ site, and I wanted to get an understanding of their differences in person. With the help of one of the cutlers there, I checked out a Tadafusa petty, comparing it to a petty of similar size by Yoshikane. The latter was nearly twice as much as the former. The differences between these two knives is completely opaque on ChefSteps’ site (and, indeed, not easy to grasp based on any internet listing alone), but were obvious when handling the knives in person.
Both blades are carbon steel. The less-expensive Tadafusa blade has a central core made of something called Blue Steel, which is high-carbon steel to which some tungsten has been added for extra edge retention capability. This core is ‘jacketed’ by layers of low-carbon steel. The resulting blade is notably thicker than most Japanese blades, and the whole knife feels ‘top heavy’ and poorly-balanced as a result. This isn’t to say it’s a ‘bad’ knife by any means; the blade indeed holds a keenly-sharp edge and is easy to sharpen.
But it only takes a moment of holding the more-expensive Yoshikane to understand the differences. The Yoshikane blade is much thinner by comparison, and feels notably more balanced. The fit and finish on the blade feels more considered, and a feature I greatly appreciate on it is a rounded back edge of the blade, which makes it much more comfortable when sharpening (the typically-square and often-crisp rear edge of most knives can cause blisters or calluses if one sharpens them frequently).
By this point, I felt like I had a decent enough understanding of how to shop for a knife. But now I was fascinated by how to actually MAKE a knife.