We recommend dedicating a brush to wax/salve. When you are done using it, offload it as much as you can onto a paper towel. Then store it in a zip lock bag until the next use.
If your brush gets dirty, or you want to wash it, soak the brush for about 20 minutes with hot water and our Bad Ace Brush Soap and Preserver. Then give it a good lather and rinse well. The Brush Soap is awesome—smells great and it’s an all-in-one solution to wash all of your paint brushes (and your hands) after paint, primer, and topcoats too!