Whether real or synthetic I always use a mild soap (usually baby shampoo). Simply rotate your brush in a circular motion on your hand or flat surface, repeat as needed, then rinse in cold/warm water with brushes facing the drain. Try not to drown the brushes in water because the hair is glued to the base and bristles will start to fall off. :-( If you are worried about using too much water while cleaning, use a bowl for cleaning and one for rinsing.
Next, genitally squeeze out moisture with towel or fingers, shape bristles back to original shape and either let them hang off the side of something or place upright in a brush holder.
Here is to clean brushes for beautiful flawless skin!
Love Sweet Candy Girl!<3 <3 <3