JMG SteelWorks

​Craftsman Knives & Razors. Handmade. With No Compromise. 

The Hamon

I love finding simple beauty in things. It’s that final touch that nature puts to a rose, or the giant tree that Bob Ross places into his painting. It’s th simple beauties, that have a way of capturing my attention. And it is that way with my handmade chef knifes and razors. I put into each, a unique and signature Hamon.

The Hamon is created by use of a hardening process that is mostly employed in sword smithing, and has recently been receiving greater attention from handmade craftsman knife makers.

But, what IS the hamon?

The Hamon is a visual demarcation line that separates the hardened cutting edge of the blade from the softer spine. Knives that use this technique for heat treating  are commonly known as differentially hardened. Their cutting edge, when done properly, is harder than the back of the knife or the spine.  There are several ways to achieve this, but my way is the process of applying a special clay to the blade just before heat treat, so that when it is clenched the part of the blade covered in clay will cool slower than the uncovered part. This difference in cooling rates is what hardens, or does not harden the steel. It is in utilizing an exceptionally fast speed of quenching the steel when it is at its terminal temperature, that gives it, it's hardness. And to obtain a hamon a very, very fast quench is needed.

For my handmade knives the quench is done in oil. It might seem surprising as most would expect that the fastest quench of hot steel comes from water. But in truth, when you need it done lighting quick oil will actually cool your terminal temperature blade much faster than cold water. In fact it's best if the oil is warmed somewhere around 152°F to 170°F.

So why is that?

Because as you place the glowing hot steel into the water, it creates a barrier of steam around the steel preventing the cold water from touching it, thus slowing the quench process. Whereas the oil doesn't do this, and will completely cover and encompass the blade drawing out the heat much faster, which is the crucial thing necessary for drawing out the Hamon and hardening the cutting edge of the steel.

I see the Hamon as the physical representation of the transition between the harder martensitic steel and the softer pearlitic steel. It also doesn't hurt that the Hamon can be beautiful, adding a quality and a signature to the blade that is representative of a particular artist who creates that steel.

Modern-day factories are always trying hard to replicate the craftsman, but to do so at a savings of time and costs and in many cases without actually doing the craftwork. These reproductions do not have a natural Hamon because they are fully hardened mono steel. In other words, hardened to the same amount throughout the entire blade. They try to reproduce the appearance of the Hamon with various types of sandblasting, etching or even the horrible wire brushing. (Sends a little shiver down my spine...) A true natural Hamon can be easily identified by the presence of a, “nioi” which is a bright spectral line a few millimeters wide following the full length of the Hamon. It is best viewed at long angles and cannot be faked by sandblasting or other methods. When viewed through a magnifying lens the nioi appears as a sparkly line, being made up of the many bright martensite grains in the steel, which are surrounded by the darker softer pearlite.

Upon close inspection of all of my Hamon blades you will always be able to see the, nioi. I purposefully and only harden my blades using a special clay and a Hamon design and pattern that to my eye best suits the blade. It is beauty and function rolled into one showing the owner of my blade exactly where the demarcation line is between the hardened cutting edge in the softer spine steel allowing that the blade can be dropped without shattering and can be sharpened to cut like a razor, that will hold its edge far longer than any stainless steel knife ever could.

The Haman is for me, true simple beauty. It is functional art. It is my personal touch as the maker, on every blade I make.

 
John Glueck
The Maker