Carbon steel is typically defined as an alloy of Iron and Carbon in which the main interstitial alloying constituent is Carbon (Ranging between 0.12–2.0%). Some definitions also state that their total mass should contain no more than 1.65% Manganese and no more than 0.60% Copper. Unlike Stainless Steel, Carbon Steel contains either little or no elements that reduce corrosion, which means that it can discolor and rust relatively easily. Consequently, it requires more care and maintenance than Stainless Steels.
We recommend that you do not leave Carbon Steel knives in wet conditions or in contact with water for any significant length of time because it can cause discoloration and eventually lead to rusting. If you often work with wet foodstuff, please keep a soft absorbent cloth or towel nearby so that you can frequently dry the knife whilst working. We similarly recommend that Carbon Steel knives that come in to contact with salty foods or liquids should be cleaned as soon as possible in order to prevent corrosion. It is normal for an oxidized ‘patina’ to develop on knives which are used with acidic foods or foods which contain a lot of protein. Some people like this discoloration and it does not affect cutting performance, but it can easily be removed using cloth and some mildly abrasive cleaning powder, such as Bar Keepers Friend. This cleaning method will minimize the chance of damaging the appearance of the knife. To remove more serious corrosion and rust we suggest using the ‘rust eraser’ type of abrasive rubber blocks, starting with the finest abrasive version first, to minimize damaging the appearance of the knife.
It is also especially important to dry the blade and handle of Carbon Steel knives after hand washing because any remaining water might lead to discoloration and eventual rusting. Before storing the knife, we advise that the blade is given a very light coat of a non-perishable oil that is relatively P.H. neutral, such as camellia oil (Tsubaki Oil), jojoba oil, Ballistol All-purpose Oil, or mineral oil. Place a small drop of the oil on a soft clean cloth, kitchen paper, or a disposable tissue. After oiling, please put the blade back inside the folded piece of corrosion-inhibiting paper that it was originally shipped with, as it will help to prevent corrosion.
Having read about the special care and maintenance that Carbon Steel kitchen knives require, you might wonder why some people prefer them to Stainless Steel knives. Some people continue to use Carbon Steel knives due to their respect for cultural traditions, whilst others believe that they offer a better balance of edge sharpness, edge retention and ease of sharpening than Stainless Steel knives. Indeed, because many culinary professionals need a knife that retains maximum sharpness throughout their long working day that is also easy to sharpen, they prefer to use High Carbon Steel knives. This is why they are very popular with professionals who make dishes that use raw ingredients, such as Sashimi (Raw fish) and salads, since the ingredients have to be cleanly cut in order to retain the best possible texture and flavor (Roughly cut surfaces frequently suffer from excessive oxidation, which can spoil the flavor of the food). Many knife enthusiasts also prefer Carbon Steel knives because, unlike Stainless Steel knives, they can build up a patina which they believe adds personality, history and beauty to a knife.
Just as the legendary cutting performance of Japanese swords made of Tamahagane (“Jewel Steel”) is known worldwide, Japanese Carbon Steel kitchen knives also offer excellent cutting performance. In fact, the high purity Shirogami ("White Steel”) group of steels, which are made at the Yasugi steel works of Hitachi Metals Ltd., were originally developed to emulate many of the desirable qualities of Tamahagane (“Jewel Steel”). Hitachi use White Steel No.2 as the starting point for creating many of the other steels which they produce, including White No.1 steel, the Aogami ("Blue Steel”) range of steels and also Aogami Super steel.
A Note About Laminated Carbon Steel Knives and the "CarboNext (ES) Series”
For customers who would like to try the benefits of a High Carbon Steel blade, but are worried about corrosion, we recommend trying a knife with a laminated blade that features a High Carbon Steel blade core and outer cladding layers of either soft Stainless Steel or beautiful 'Stainless Damascus Steel'. Because only the central core of these laminated knives has the possibility of discoloring or rusting, these knives are much easier to care for than regular Carbon Steel knives. Alternatively, please consider our innovative “CarboNext (ES) Series” of knives, which offer the same advantages as High Carbon Steel knives but also better corrosion resistance.