The main purpose of a shave brush is to transport and incorporate water with the shave soap into a frothy lather that will moisten and soften the beard. How you get this job done with as little effort as possible depends on the quality of the bristle.

There are three types of bristles used in making shaving brushes:

Synthetic bristles, usually nylon, or mixed with boar or badger, do not do a good job of transporting water to the shave soap because the bristles are usually non-absorbent. They are typically stiffer than natural bristle. Due to their stiffness and lack of absorbency, a foamy lather is hard to obtain and is not easily applied to the face. One advantage is that they are easy to keep clean of soap residues and dry very quickly.

Boar bristle brushes are more flexible, but yet, can be a little stiff because they come from the upper back of the animal. Boar bristles may become brittle over time and may result in splitting away with uneven tufts. Overall, boar bristle brushes can do a good job and are in the middle to lower price range.

Pure Badger bristles, especially the silver-tipped bristles, are best suited for the job of incorporating water (very absorbent) and the shave soap into a thick, frothy lather, which when applied to the beard, does the best job of getting the beard ready for a close and comfortable shave. They can tend to be a bit pricey, especially the silver-tipped, but do the job very well and with proper care, can last for years.