Thoroughly cleaning mac 190 brush?

i use baby shampoo to clean all my brushes which does a good job. but with my 190 (which i use for liquid foundation) i will put some soap in my palm, swirl and really work the soap into the bristles, rinse and end up doing this multiple times till it runs clear. but there is still product inside the bristles! i just want my brush to be like the day i bought it