Brush hair material, mainly divided into badger, hog bristle (boar/hog bristle), horse hair (synthetic). As a shaving brush this is naturally the most important distinction, but also the basis of shaving brush classification and fundamental.
Backbone, resist the force is not easy to bend, keep straight, straight ability, brush to the attribute of the stronger the better. It should be noted that some people call backbone rebound and describe it as the ability of the bristles to restore the original straight and straight shape after a short stress, which is different from the original concept of backbone. In fact, the bristles that are easy to bend and restore to original state are poor bristles of backbone.
The degree of softness (softness)/scritch (scritch) is not an objective technical parameter, but is a common factor in reviewing brushes, namely the literal meaning, the degree of softness of the brush, and whether or not the face is shaved. Soft nature is good without affecting other performance.
