MAC Brush Cleanser to clean all of my brushes. I don't have the product in it's original packaging because the bottle comes with a pouring head rather than a spray top so I bought a spray bottle and use it in that instead.
The spray is 233ml and £8.50 (current price) but lasts forever as you don't need much at all! It is really effective, smells nice and not clinical smelling but not overpowering either, and will clean even the dirtiest eyeliner brushes really quickly.
Step by step of how I clean my brushes
First I get a cotton pad and spray about 3 sprays on it. I like to have enough on that the brushes clean straight away, but not too much that the brushes get soaked.
Then I find a used (or very used in this case) brush..
..and then sweep it across the cotton pad with the cleaner on it. I basically just move it around as if I was painting and keep doing it on both sides until it's clean..
You can really see how much it cleans off! This was one eyeliner brush with Maybelline Lasting Drama Gel Liner on it.
After my brushes are clean, I reshape them and leave them to dry. Within 5-10 minutes (depending how much cleaner I put on) they are ready to use!