Every knife user – professional or amateur, will have their own preference of handle design, weight, balance and overall appearance. These aspects cannot be contested as they are down to individual choice. However, there are facts governing knife design and sharpening methods, which apply to all culinary knives.

i. All steel is rated for hardness using a Rockwell ° rating system. The harder the steel, the higher up the scale it goes. The maximum level of hardness for stainless steel is Rockwell 62°. The higher the grade and therefore harder the steel used for the blade cutting edge, the higher the level of sharpness the cutting edge can obtain and the longer it will stay sharp.

ii. With increased hardness also comes increased brittleness. If the knife is dropped or used to chop bone, it is more likely to break or chip. Damascus knives are tempered and layered to a hardness of Rockwell 60 -61° to avoid brittleness. I.O.Shen have sandwiched soft steel around Rockwell 62° to protect the inner layer.

Most other knives are a single piece of steel with a limiting factor of Rockwell 58°.

iii. High quality knives can have an edge sharpened to razor sharpness (capable of shaving human hairs) but this high level of sharpness can only be maintained briefly if the knife is in constant use. However, the level of working sharpness (where the knife can no longer shave hairs but is still extremely sharp and will cut food items efficiently and effortlessly) will be maintained for far longer than a steel blade of lower grade.

iv. Low-grade steel blades (e.g. less than Rockwell 40° hardness) cannot ever sharpen to razor standard.

v. Any form of knife sharpening involves the removal of material from the cutting edge. Once the knife is as sharp as the blade steel and the sharpening method will allow, further sharpening serves only to remove excess steel and reduce the working life of the knife.

vi. Any form of knife sharpening involves the use of an abrasive contact with the cutting edge to remove steel. After a time an undesirable shoulder will be produced (a distinct angle change between the cutting edge and the side of the knife blade). A good sharpening system will allow the operator to remove a shoulder and re-create a gradual profile.

vii. Any hard abrasive object i.e. grinding wheel, steel, diamond steel, oilstone or whetstone; will impart scratches to the cutting edge. The coarser the abrasive, the more pronounced and deeper the scratches. The patented cushion contact system used on Nirey KE-280 & KE-168 produces a unique polished edge finish to the cutting edge

viii. A knife sharpened on a coarse abrasive can still feel sharp. Indeed, for cutting some food items e.g. tomatoes, the rough edge will be extremely effective but for cutting fibrous items e.g. meat, the rough edge will drag on the meat fibres, producing a rough cut and involving higher operator effort.

ix. Any sharpening method that does not guide the knife e.g. sharpening steel or plain whetstone, relies on the operator to set and maintain the sharpening angle (bevel angle on the knife edge). In practice, this is virtually impossible and although a sharp cutting edge can be created, the original profile of the cutting edge will be gradually lost, as will the durability of the edge. Both the KE-280 and the KE3000 have a guide system to assist the operator.

x. The bevel angle of the cutting edge varies according to different knife manufacturers. The minimum we know is 13°, the maximum 29°. The greater the angle, the greater the effort required to cut. Too narrow an angle would result in a fragile cutting edge. 15° is regarded by Knife Wizard as the best compromise.