Choose Your Blade Material
Section 3: Choosing Your Blade Material
The material your shear is made from will determine how long it can go without sharpening and how fine the edge can be. Of course, how you care for your shears has an impact on their lifespan, so unless you are prepared to care for them carefully, you may not want to invest in the highest quality material.
Due to years of innovation and development, today’s shears can be crafted from a dazzling variety of different materials, the most common of which are explained below.
Forged vs Cast Blades:
For centuries, cutlery makers have known that forging, or using compressive force to shape metal, yields a material that will stay sharp longer. In the middle ages they would pound the sword with hammers to drive the molecules more tightly together. Today cutlery is drop forged with tremendous weight being dropped onto the mold to pound the steel into the shape desired. The steel is heated to about 1200F and then the forging is done. After forging, the steel is put into a cold oil bath to crystalize and harden the steel (see ICE TEMPERING). This will leave the steel compressed and strong and able to hold and edge well or stay sharp for a long time.
The other method to give a blade it’s shape, is to cast the metal. This involves heating the metal to a liquid form or around 2500F. The liquid metal is poured into a mold. The problem with this method is that when the metal cools in the mold, it expands. This leaves the molecules much more widely separated. As a result, cast shears do not stay sharp as long as forged shears. The second problem with casting shears, is that they often become brittle. Not only will they chip or nick more easily, but service technicians can not make adjustments to the arch of the blade without it breaking. Therefore, cast shears have an overall shorter life span than forged shears.
Note: It is almost impossible to tell cast from forged shears by sight. Unfortunetly it may also be difficult to get a reliable answer by asking the sales person since they often do not know the true answer to that question. Most shears from Taiwan and many from China are cast. Again the problem is many shears are not marked with a true country of origin. In this regard, it is often best to deal with reliable manufacturers with enough of a history to back up their warranty.
The Different Materials
Most shears are made using an alloy of some sort. Alloys are made by combining two or more metallic elements to give greater strength or resistance to corrosion. A shears’ life, sharpness and resistance to damage can be increased depending on the base metal used in the alloy and those it is combined with.
Health Note: Nickel is added to almost all the alloys, mostly to make the material shiny and to improve corrosion resistance. Some people are allergic to nickel which can cause skin irritations. The best solution is to dip the handles in a rubber tool handle dip you can buy on line or in some hardware stores. If you do this, you’ll need to remove the dip where the handles contact to keep the tips crossed properly.
Stainless Steel Alloy
One of the most popular and common alloys used in scissor manufacture is Stainless Steel. It is very easy to care for and holds a cutting edge well if it is properly heat treated. The two main types of stainless steel used in haircutting shears are 420A and 440C. The best stainless materials are those that come from Japan and Germany since both countries have long histories of cutlery making and both have focused on making very refined steel for this purpose. The 440C material holds the edge best because it has a higher carbon content and can be tempered to a higher hardness.
Cobalt Base Alloy
Cobalt Base Alloy is another extremely popular material used in today’s scissor manufacture. Cobalt has superb rust and chemical resistance. The problem is it can chip and nick easily and the blades cannot be adjusted after multiple sharpening. True cobalt alloy shears tend to wear out sooner than their Stainless counterparts and yet they cost more than Stainless alloy shears.
This is an ideal material as a step up from Stainless or Cobalt alloy. It can be hardened to a high level without becoming brittle because molybdenum is flexible. This material can accept a very fine or sharp edge and will hold up quite well compared to either stainless or cobalt alloy.
Cobalt Molybdenum Base Alloy
In order to overcome the brittleness and fragility of shears forged from a Cobalt Base Alloy, Molybdenum is added to the alloy, creating a tough, high strength, durable material which retains the chemical and rust resistance of a Cobalt Base Alloy without its fragility.
Sintered Steel & Carbide Steel
There are other exotic materials being used in some of todays most expensive shears. Sintered or powdered steel can have extreme hardness but can be brittle and hard to sharpen. Carbide steel can be extremely good at edge retention. Because it is very difficult to manufacture shears from these material, you will find the prices tend to be quite high. Only stylists who can afford these and also who are prepared to care for them carefully should consider these exotic materials.
Other terms related to the materials shears are made from:
Titan or Titanium Coating
This is a way to add color to shears. It has no positive impact on the edge retention since it is not on the edge of the shear. It is usually done to inexpensive shears to make them appear more attractive. It can be good for those with nickel allergies. It can flake off, damaging the edge.
ICE Tempering Process
Most hair shears are made with a process called ICE tempering. This method involves the steel being heated and then quenched in a ice cold oil bath. The quenching process crystalizes the metal making it harder and better able to hold a sharp edge.
Cryogenic Deep Cold Tempering Process
This method is used by several manufactures and it expands on ICE tempering by bringing the material down to approximately -300f. This pulls the molecules of the steel tightly together. Then the steel is slowly returned to room temperature. The molecules drift apart but now they separate according to physics in a controlled way. The result is a more organized structure to the steel that has been shown to improve edge retention by as much as 40%.
- Scissor Education (Section 1)
- Forged vs Cast Blades
- The Different Material
- Stainless Steel Alloy
- Cobalt Base Alloy
- Molybdenum Alloy
- Cobalt Molybdenum Base Alloy
- Sintered Steel & Carbide Steel
- Other Blade Material Terms