I actually just cleaned my eyeliner brush today and it feels so soft and feathery. I wish I had more that needed cleaning!
Shampoo and Conditioner
I used this method of cleaning for my brushes because it is the simplest and the quickest one to use especially since these are usual household items.
1. Run some warm water
2. Run water over the brush, holding it as you would a writing pencil.
3. Use a drop of shampoo and very gently massage it into the bristles of the brush, be very careful.
4. Run the brush against the palm of your hand to release the bristles and release the paint trapped within them, then repeat step 3.
5. Completely rinse out all the shampoo, and apply conditioner. Repeat Step 3 but with the conditioner not shampoo.
6. Rinse, Dry with a towel or a cloth carefully and then you're finished.