With some care, a quality shaving brush will last for years.
Squeeze, rather than shake, a water-soaked brush.
A natural tendency when you have a brush dripping with water is to give a flick of the wrist to shake the water out. Many natural hair brushes hold considerable amounts of water and are designed to trap water inside. When you shake the brush, there’s a large amount of centripetal force applied to the heavy, water-soaked bristles and this can cause the bristles to loosen from the handle over time.
Gently squeezing the brush in your hand will wring out most of the water. If the brush still feels damp, a quick shake at this point can safely remove the remaining moisture.
Rinse out the soap after each use
Allowing soap to dry on your brush will result in soap film building up on the bristles. Over time, the brush will start to feel stiff and won’t hold water as well as it did when it was new. After every use, rinse your brush out under running water, squeezing it a few times to release the soap that’s deep inside.
Let your brush breathe
After washing out your brush, allow it to dry out in the open. Putting it in a drawer, or closing it up in a shave kit can encourage mold and bacteria growth. You wouldn’t shove a damp towel in a bag, and you shouldn’t do it with a damp shaving brush either.
It’s best to leave your brush sitting out on the counter where it can get plenty of dry airflow around it. Standing it up on the handle with the bristles facing up is OK, although it won’t dry as well that way. Hanging it bristle-side down from a shave stand is best, as this allows any water droplets to drip out of the brush.
This has the added bonus of helping your brush keep its shape. When you sleep with wet hair, your hair is unmanageable in the morning, and the wet hair on a shaving brush will fare no better when left resting against the contents of your bathroom’s junk drawer.
Bonus tip: Drying a brush during travel
I travel extensively, and often need to pack my shaving stuff up to check out of a hotel before my brush has a chance to fully dry. I travel with an inexpensive boar hair brush for two reasons. First, It’s cheap enough that if I accidentally leave it behind at a hotel, it’s easy to replace. Second, boar doesn’t hold water as well as badger, so it dries more quickly.
To aid in the drying of the brush, after I’ve rinsed out the soap and squeezed out the water, I place a hand towel on the counter and dry my brush on it, using a motion just like I’m lathering up some soap. Then I can put the brush away in my shave bag. When I get home, I’ll take it out and allow it to dry fully.