I use Japonesque (Parian Spirit), or Vincent Longo brush cleanser while on location to keep brushes clean/sanitized between faces/colors. I tend to shampoo my brushes a couple times a week, depending on how much work I have been doing.
For the deep clean:
>In a large stainless steel mixing bowl (2qt), I put 4oz warm (not hot) water, 1/4 cup 99% Alcohol and Aveda Sap Moss shampoo (about a tablespoon)
>In a stainless steel pinch bowl, I put a dollop of same shampoo
Helpers: 1 large empty stainless steel cup (lay on its side), 4-8 solid white sheets of paper towel, 1 clean cotton hand towel
1. I take the clean cotton towel and do a dry wash to remove much of the make-up residue that is there (wipe back and forth & in swirling motion)
2. Then I take each brush (one at a time) and swirl in the large bowl, gently pressing it against the side of the bowl to really get it saturated
3. Dip my finger in the pinch bowl to put a little shampoo in my palm to gently swirl the brush in (dip in large bowl and repeat until suds is white)
4. Brush gets one final swirl in the large bowl mixture, then a gentle squeeze to remove excess water. Clean brush is then inserted into the stainless steel cup (remember, lying on its side so the water doesn’t invade the ferrule)
5. Repeat steps 1-4 until every brush is done.
6. Empty large bowl and rinse well. Then refill half way with warm water, 1/4 cu alcohol and a tbl spoon of Pantene Relaxed & Natural Conditioner (or any moisturizing conditioner). Whisk with a fork to blend. (mixture will be slightly cloudy)
7. Take each brush and rinse under running water for about 10 seconds – a little longer for larger brushes. Squeeze out excess water
8. Swirl brush in water/conditioner mixture for a few seconds, then again squeeze out excess liquid
Lastly, use the paper towel to gently squeeze out excess water and lay brushes flat to dry overnight. I use solid white paper towel. As you squeeze out water, it is easy to see that you have cleaned the brush thoroughly if no make-up residue stains the paper towel
It takes me about an hour and 40 minutes to do my entire collection (300+ brushes)
Of course you can use whatever shampoo/conditioner you want. This method has worked for me over the years. I have many brushes that are in their late teens/early twenties and still in superb condition.