Editing Blade (section)

===Dulling===
Blades dull with use and abuse. This is particularly true of acute blades and those made of soft materials. Dulling usually occurs due to contact between the blade and a hard substance such as ceramic, stone, bone, glass, or metal.
[[File:Common Edge Deformations.jpg|alt=First, spiral shearing occurs when a soft edge forms a metal ribbon, stripping away material but allowing the blade to be re-sharpened. Second, impact deformation happens when the blade strikes a hard object, creating divots, rolling metal, and potentially stressing the backbone of the knife. This often requires material removal to restore the edge. Third, scrapes appear on the sides of the blade after use. While initially cosmetic, these can lead to stress fractures and blade failure if significant material is lost. These examples demonstrate how a blade's material and sharpness degrade over time.|thumb|The figure illustrates four common blade deformations that can occur due to use or misuse. Images captured using a stereo microscope. ]]
The more acute the blade, the more easily it will dull. As the blade near the edge is thinner, there is little material to remove before the edge is worn away to a thicker section. Thin edges can also roll over when force is applied it them, forming a section like the bottom part of a letter "J". For this reason, [[straight edge razor]]s are frequently stropped to straighten the edge.

Drawing a blade across any material tends to abrade both the blade, usually making it duller, and the cut material. Though softer than glass or many types of stone used in the kitchen, steel edges can still scratch these surfaces. The resulting scratch is full of very fine particles of ground glass or stone which will very quickly abrade the blade's edge and so dull it.

In times when swords were regularly used in warfare, they required frequent sharpening because of dulling from contact with rigid armor, mail, metal rimmed shields, or other swords,<ref name="thearma.org; edge damage"/> for example. Particularly, hitting the edge of another sword by accident or in an emergency could chip away metal and even cause cracks through the blade.<ref>Yang, Jwing-Ming (1999). ''Taiji Sword, Classical Yang Style''. YMAA Publications, p. 20. {{ISBN|978-1-886969-74-2}}</ref> Soft-cored blades are more resistant to fracturing on impact.