The elasticity of the nib is different: the strengthening of the brush is to add a slightly hard material to the nib, so that the nib has moderate elasticity and is convenient for writing. Double-handle brushes are made of wool and other bristles in a certain proportion. The combination of rigidity and softness not only keeps the water storage of wool, but also has the strength and elasticity of bristles. It can be dyed, scratched, hooked and easy to master.
Different materials are used: weasel hair or old rabbit neck hair is added to the soft brush to make the brush tip soft and hard, thus strengthening the brush. Double double brush often takes soft hair as the core, and hard hair is long and covers it.