The Hamon - Parts of a Japanese Katana
The Hamon is recognized as the sharpened section of the blade and is a result of differential hardening. In a traditional Japanese katana the blades spine is coated thickly with a special clay and thinning out greatly before the edge. This enables a master sword smith to control the speed in which different areas of the blade change temperature during the heating and cooling process of tempering. The result is a harder cutting edge and a softer spine. The hamon is revealed through expert polishing and will show itself as a slightly different shade from the rest of the blade. This is difficult for some people to see, so it is a common practice in modern day to acid burn the hamon to make it more visible. This shouldn't be mistaken for an artificial hamon even though the technique is similarly used. Artificial hamon's are sometimes produced on mono-steel or through hardened blades. These swords are made for beginner to intermediate martial artist but aren't differential hardened which is the only way a hamon is produced. An artificial hamon may be applied to the blade so it looks aesthetically correct to the traditional tempered blades.
These are some photo's of several different Hamon found on the Japanese katana that we offer.