Honing vs Sharpening: What's the Difference? | CRATEX Abrasives

There are a lot of people out there who are not really sure what the difference between honing and sharpening is or might think they are the same thing. You just might be one of them. There is a short and a long explanation to this matter, so we'll do our best to provide both.

Short explanation: Sharpening is removing material from the workpiece to create a sharp edge, while honing is just straightening out the edge of a blade that is already sharp. You can say that sharpening is grinding, while honing is truing.

Long explanation:

Sharpening

Sharpening is the process of creating a sharp edge on a tool designed for cutting. It is done by grinding or removing the material with an abrasive substance of higher hardness (according to the Mohs scale than the material that is being sharpened.

The most traditional materials for sharpening are sandstones and granite, but most commonly used today are flat sharpening stones and various grinding wheels. Diamond is a very hard abrasive, but also very expensive one, while synthetic abrasives and natural Japanese waterstones are cheaper, but also less hard.

Honing

On the other hand, honing is the process of creating a precision surface on a metal workpiece by using an abrasive stone called honing stone. Honing stone is similar to a grinding wheel , but is more soft and friable, so it wears in and conforms to the shape of the workpiece.

Unlike sharpening, honing is just the process of preparing or maintaining an already sharp edge. Preparing the surface involves removing burrs or wire edges after you perform sharpening and maintaining the blade edge by polishing out small imperfections or marks caused by regular use. Honing should be done on regular basis, as it will keep the microscopic edge straight and make the need for sharpening less frequent.

Burr and Wire Edge

There are two phenomena that you should know about that are directly related to the process of sharpening. Namely, the sharpening process causes two things to occur: a burr and a wire edge. Many are not aware of the difference, but it does exist, and we'll try to explain what that is exactly.

Raising a burr is an essential part of the sharpening process. For all those who don't know, a burr is a small metal fold or piece that forms at the tip of the cutting edge, on the opposite side of the grind. Raising a burr is important because it is a signal that you've ground the edge thin enough and that you should proceed and start sharpening on the other side of the bevel.

If the burr doesn't form during the sharpening process, it means that you haven't sharpen the blade fully, so it's not as sharp as it could be. Forming the burr can be particularly difficult in case you are using coarser stones to sharpen the blade.

Namely, if you use too much pressure on a coarser stone, you may either create a much larger burr than necessary or not create one at all. The higher the pressure, the less the possibility to keep a consistent angle when sharpening which will affect the ability to raise a burr. This is why using a light pressure is key for chasing the burr. The process might take longer, but the results will be perfect.

Wire edge also falls out of the geometry of the edge. It is a continuous round wire of metal that is formed on the blade by the sharpening process. When you are back-stroking the blade or sharpening it in the spine-to-edge direction like you would by using a belt sander, you'll crate a metal buildup on the blade, resulting in a rolled round edge. Note that if you use wetstones and go in both directions as you sharpen, the wire edge won't appear.

A wire edge can begin its life as a larger burr that gets polished down instead of being ground away. It can also occur on thin blades when the edge flexes away under the pressure of the grinding tool.

Wire edge may look sharp, but it's not – it is fragile and prone to chipping. It takes time and patience to go from a burr to a wire edge and then to a clean, sharp blade. This is why you'll use progressively finer abrasives until the final burr or the wire edge can be polished off with a high-grit stone.

Sharpening Stones

Whetstones or wetstones (nothing to do with being wet, but word "whet" which means "to sharpen a blade") can be natural (typically formed of quartz) or artificial, that usually come in the form of some bonded abrasive made of a ceramic, usually silicon carbide or aluminum-oxide. As you might imagine, artificial stones provide faster cutting action and are more efficient than the natural stones. They are often found as double-sided blocks that have coarser grit on the one side and finer grit on the other.

Other common forms are bench blocks, that are intended for installation on a bench, and pocket stones, that are smaller and portable (thus the name). Although using pocket stones might make it difficult to maintain a consistent angle and pressure when drawing along longer blades, they still can form a good edge and are excellent asset for "field work" honing.

Steel plates are available in various grits and sizes and are sometimes mounted on a resin or plastic base and coated with diamond grit (better known as diamond stones). Coarser grits are used for coarser grinding or removing larger amounts of metal more rapidly, for example, when forming an edge or restoring a damaged edge. On the other hand, finer grits are used to remove scratches created by coarser grits and to refine the edge.

Sharpening Angles

The angles on each side of the blade need to create an edge that is sharp enough to cut through a certain material. The rule is simple: the smaller the angle, the sharper the cutting tool. Greater angle means more metal to be cut, which provides more durability in the field and a longer lasting sharpness.

For example, you would consider a knife very sharp in case it is sharpen at 10 degrees per side (knife's edge includes a 20-degree angle). The sharpest cutting tools, such as razors, fillet knives and paring knives are sharpened at an angle between 12 and 18 degrees, while most kitchen knives (carving and boning knives, chef's knife, etc.) are sharpened at 15-25-degree angle (Japanese knives go between 14 and 16 degrees).

Pocket, survival and hunting knives or (sporting knives)are usually sharpened at 25-30-degree angle. Extremely durable edges of about 30-40 degrees can be seen on a machete, ax, chisel or a draw knife.

In case you are not dealing with a straight edge instruments, sharpening angles and tools might be different. For example, drill bits are sharpened at 60-degree angle from vertical (120 degrees total), typically on a grinding wheel.