What is 1055 Carbon Steel?
1055 steel is right on the border between a medium and a high carbon steel, with a carbon content between 0.50%-0.60% and with manganese between 0.60%-0.90% as the only other component. The carbon content and lean alloy make this a shallow hardening steel with a quenched hardness between Rc 60-64 depending on exact carbon content. These combination of factors make this one of the toughest steels available because, when quenched, it produces a near saturated lathe martensite with no excess carbides, avoiding the brittleness of higher carbon materials. This steel is particularly suited to applications where strength and impact resistance is valued above all other considerations and will produce blades of almost legendary toughness.

Q: What is SK-5 High Carbon Steel?
SK-5 is the Japanese equivalent of American 1080, a high carbon steel with carbon between 0.75%-0.85% and 0.60%-0.90% manganese. As quenched, it has a hardness near Rc 65 and produces a mixture of carbon rich martensite with some small un-dissolved carbides. The excess carbide increases abrasion resistance and allows the steel to achieve an ideal balance of very good blade toughness with superior edge holding ability. Due to these characteristics, this grade of steel has been used traditionally for making a variety of hand tools, including chisels and woodcutting saws, and has stood the test of time and use over many years in many countries.

Q: What is Rockwell Hardness?
The hardness of steel or other metals is usually measured on a scale called the "Rockwell Scale", this scale gives a number value to the hardness. This number is preceded by the letters Rc (for example Rc58). High numbers indicate harder material. If a knife is too "soft" meaning it has too low a Rockwell hardness, it will probably not hold an edge and will bend quite easily. If a knife is too "hard" meaning it has too high a Rockwell hardness, it will probably be very brittle and difficult to re-sharpen. When a knife is designed, it is important to determine from the beginning what kind of hardness will be required for its ultimate purpose. This will affect the choice of steel. Once the steel is chosen, a heat treatment sequence must be devised to result in the exact hardness needed in the final knife.

Q: What is the difference between a Saber Grind and a Flat Grind?

 These two grinds are quite similar. They are both actually "flat", as opposed to concave (hollow ground) or convex. However, a "Flat ground" blade is typically ground uniformly from the blade back right to the edge. Where as in a "Saber ground" blade, typically only half the width of the blade is ground. The rest remains full thickness, like a traditional saber, hence the name.

Q: What is the difference between a Rolled Edge and a Cantled Edge?

 Cantled Edge is the most widely used edge configuration. It consists of a final grind along the very edge of the primary grind. This final grind forms the sharp edge of the knife. One of the main reasons for its popularity is that the cantled edge is fairly simple to apply by hand or machine. It is also relatively easy to control the angle of the cantle to achieve a desired degree of sturdiness or fineness to the finished edge.
The Rolled Edge has been in existence for over 1,000 years and has been used by bladesmiths all around the world. But today it is qui te rare in the knife industry. Some of the finest examples of this edge can be found on early Japanese Katanas. It consists of a continuous curve from the primary grind right to the edge of the knife. There is no "cantle" at the edge visible to the naked eye. The only knife that Cold Steel currently makes with a rolled edge is the Stainless Trail Master. A rolled edge is quite difficult to produce in custom quantities and practically impossible in full scale production. The reason for this is that it must be applied by hand, using a "slack belt". The honer must constantly monitor his progress very carefully to develop a perfect rolled edge.
However, the result is a cutting edge that will easily outperform a standard cantled edge, because it offers almost no friction during a cutting stroke. It slips effortlessly through the cutting medium. Apart from the difficulty of manufacture, the drawbacks to this type of edge are that it is typically very fine. This means that it is subject to chipping if it comes in contact with very hard materials such as bone. It is also difficult to re-sharpen by someone inexperienced with rolled edges. The only recourse for this individual would be to send the knife back to Cold Steel for factory resharpening or to develop a cantled edge in place of the original rolled edge

Q: How can I re-sharpen my serrated knife?
With care, your new knives will remain sharp for a very long time and may never need to be resharpened. If they do start to need resharpening it can be done in one of two ways: First, the back of the serrations can be lightly honed with a standard sharpening system to bring back the edge on the points and flats of the serrations. This method is fairly quick, but if done too aggressively or too often, it will damage the serrations.
Alternately, a sharpening system with very fine angles can be used to sharpen between the serrations on the front of the knife. This technique is quite time consuming but it is the only way to restore the edge properly. At the moment, we recommend the Sharpmaker system by Spyderco.

Q: How do you sharpen a knife?
The theory of sharpening is quite simple, although in practice it requires patience and experience to become proficient. The basics are as follows: Start establishing a cantle with an abrasive (stone, sanding belt, etc.). Then further define the cantle by refining the scratch pattern with a series of progressively finer abrasives. A good way to see whether your edge is almost done is to look for the burr that forms along the edge and see if it is consistent all along the length of the edge. Once you have a consistent burr, remove it with a finer abrasive or a strop and your edge is finished.
For stainless steels: If the edge requires repair (to remove chips or dinks) or if the cantle has to be reestablished one should begin with a coarse silicon carbide stone (Norton's Crystolon Bench Stone). Initial sharpening should be done with a medium silicon carbide (Norton's Crystolon) or medium aluminum oxide stone (Norton's India Stone). To further refine the edge a fine aluminum oxide stone (Norton's India Stone) would be the next step, followed by a Soft Arkansas for final sharpening. If an extremely refined edge is desired, follow the Soft Arkansas with a Hard Arkansas or 6000-8000 grit Japanese Water Stone. Any ceramic system will work if there is not going to be a lot of material to be removed along the edge (the Sharpmaker by Spyderco is especially good for serrated models).
For carbon steels: The same procedure as listed above will work for carbon steels but we have had better results using only the Japanese water stones (Japanese water stones can be found at most woodworking supply stores and catalogs). We suggest beginning with an 800 or 1000 grit water stone and progressing through a 1200-1400 grit and finishing with a 6000-8000 grit stone.
Rolled edges: A rolled edge can be sharpened to its original configuration by using a slack belt on a belt sander (320-400 grit belt) to get a consistent burr and then polishing the burr off with a buffer or leather strop. One can also simply redefine the edge by establishing a cantle on it as outlined above.