So today I am back with the easiest way to clean them: pure soap and two towels.
Have one very soapy towel in your sink or in a tub.
Rub your first brush in a circular motion onto the towel.
Then once the soap seems cleared up, rince your brush very well.
Dry it into a second towel.
Lay it down to dry.
Proceed the same way for all of your brushes.