Shave brushes are what you have to use to create lather from a shaving cream, as I mentioned in my last article. They come in different models. I'll go into some detail in the next paragraphs.
Firstly, you have to differenciate between the kind of hair that the brush uses. There is badger, horse, boar and synthetic. The first kind of hair that you will hear a lot about is badger, because it has been the standard and most used kind of shave brush for a long time. Badger brushes vary a lot in the price range, they can go from only 10 dollars up to over 1000!
Next, there is the boar brush. Those are usually moderately priced, with the cheapest ones going for about 7 dollars. Still, this does not make them worse shave brushes than badger brushes. They are a bit stiffer, which makes the feel on the skin a bit rougher in the beginning, but after some use, the bristles will get softer.
Horse hair brushes are much less common, but are still used. They are a kind of brush that has been used for a long time, next to the boar brush. They feel about the same as boar brushes, but not as stiff.
Finally, there are synthetic brushes. Those are also very differently priced, depending on how good they are manufactured. I would not recommend to buy a cheap nylon brush. They do not feel very nice in my opinion, and you can get badger or boar for not that much more (whoo, rhymes!). The more expensive synthetic models are indeed very good, and nicely fabricated. Those are particularly interesting for those among us who do not want to use animal products.
Another thing that differentiates brushes is the kind of handle they have. In recent years, those handles are mostly made from synthetic material. The more expensive or antique ones are often produced from wood or metal, sometimes even ivory (this applies to antiques).
I think this should be a nice overview of what shave brushes are, and how they work. If you have any questions, please do not hesitate to contact me!