How is a sharp edge formed on steel?

At Scissorfix, we constantly preach the merits of correctly sharpened hairdressing scissors. The value to the hairdresser is clear; correctly sharpened scissors cut hair cleanly, with less effort, resulting in greater productivity and less wrist stress. These attributes are not limited to scissors; it is the case that all edge tools, such as knives, woodworking chisels, straight razors etc, require a sharp edge to work efficiently. It may be of some benefit therefore to examine the science behind sharpening in more detail.

The key to any cutting implement is the tip which contacts the material being cut. This edge is formed by grinding away steel on the sides of the cutting implement (knife, scissors etc), with a material which is harder than the material the implement is made of. In this way, an edge is formed, an acute angle, uniform to the tip.
A vital factor in forming a sharp edge on any steel cutting device is the type of alloy the steel contains. All good ones contain higher carbon content, and have a high number (55 Рupwards), on the hardness scale. The higher carbon content hardens the steel and means it will hold an edge for longer. I will explain these principles in greater detail in a later article, but for the moment, it is sufficient to note their important roles in the sharp edge. When the tool is new, the geometry of the edge is uniform, as mentioned above. Continued use rounds the tip over, evidenced by a dull cutting edge. When a sharpening stone is used to resharpen the tool, typically it is only the very tip which is worked, resulting in an edge which is now sharp again. This changes the origional  honed edge angle however, from a sharp V angle to a wider one. After a period, this needs to be restored using a grinding stone. This is a vital point of relevance to hairdressing scissors, as many of the problems the stylist encounters with poorly sharpened scissors stem from precisely this process, in that the scisssors are often grinded to the incorrect angle. In our next article, I will explain the finer points of how the sharp edge process relates specifically to scissors, details which allow Scisssorfix to correctly service your scissors.