Brushes use synthetic or natural filaments to create bristles which are typically clamped to a handle via a ferrule. Testing the mechanical strength of this connection is vital to making sure that the bristles can withstand extensive use over time without falling out.
Another key attribute of brushes is the ability to bend or flex whilst applying materials such as pastes, powders and paints, so brush stiffness is tested to ensure that the filaments are not permanently deformed with usage.
Tensile strength, bend and friction tests are commonly used to check the quality of toothbrushes, cosmetic make-up brushes, paintbrushes .. and even the brushes used on industrial road sweepers !
