On set and between clients I use aprofessional brush cleaner that evaporates out of my brushes quickly so I can use them straight away. However, every night I give them a good wash with plain old shampoo and a thorough rinse to make sure there's no build up of product. Here's how to get the job done. Grab a bunch of brushes that have the same length hairs so you can rinse them right down the the root. The metal band that connects the hairs to the handle, called the ferrule, is designed to protect the base of the hairs and keep it attached to the handle, so don't let water any higher than this band of metal!
Dampen the hairs under the tap and then swirl and glide your brushes around in a blob of shampoo to lather them up. NEVER scrub in the opposite direction to the hairs as this will distort their shape. I use Sigma's GENIUS washing glove (€25.92) that features different textures to help you lather and rinse your brushes in various directions. The mitt also makes sure my hands don't dry out from washing everyday and I can get the water really hot too!
Once you've gotten your brushes nice and soapy, rinse them through and decide if you need another bit of soap depending on how much colour you see in the water.
When you've rinsed them fully, give them a little squeeze to get them back into shape. I lay my brushes on a towel as I'm working and then press the hairs together before they go on my windowsill to dry. Make sure you leave your brushes somewhere that air can get all around the hairs and avoid standing them up in a pot as the water will soak through to the base and loosen the hairs over time.