Wash your makeup brushes with soap and water. Here's why...
To prevent the spread of viruses and bacteria and to achieve optimal makeup application results, it is important to have clean, dry makeup brushes... and the best brush cleaner is good old soap (or detergent) and water.
There are 2 main reasons why soap is the best brush cleanser.
1. Soap breaks down the outer membrane of germs, disassembling them and rendering them useless.
2. The slippery surface ensures that viruses and bacteria cannot adhere to the surface, and so the germs are washed down the drain during the rinsing process.
Not to mention...
The outer protective layer of your skin is made up of dead skin cells. When soap is used on the skin, it also removes some of the dead skin cells that make up the outer layer - causing any germs that were adhered to these dead skin cells to be removed also. While this process can strip your skin of it's protective layer (hence why it is not advised to use hard soap on your face!) you could say that soap's biggest negative is also it's greatest feature.
So how is soap different to brush cleaner or sanitiser?
Alcohol-based disinfectants are effective in breaking down most viruses and bacteria, but they don't wash them away. As a result, you must ensure that the sanitiser has reached every area where the germs could be present. If not, there is still the potential of infection.
With regards to makeup, sanitising a brush will not remove all of the pigment from the brush. So while the brush may be adequately disinfected, it may still transfer colour or product with it's next use - tainting your next application.
How often should I clean my brushes?
A professional makeup artist will use wipes to remove as much product as possible from their brushes and then work a sanitiser through the brush after each client. At the end of every job, they will wash their brushes with soap and water and leave them to air dry to ensure they don't harbour any product for their next job.
For personal use, it is not required to sanitise your brushes unless you have dropped one or it has been picked up by another person. It is recommended washing your brushes with soap and water and leaving them flat to dry (with the bristles hanging over the end of a bench so that they dry evenly) at least once per week. Don't pack away brushes whilst they are wet as the bacteria in the water can remain and your brushes will end up smelling like an old wet towel. But as long as they are washed and dry, they are germ-free and ready for your next makeup!