This is what I consider to be my 'deep cleaner' what I used to power clean all my brushes at once to give them a good cleaning to remove all traces of makeup. I only do this every three months or so because in between this I clean all my brushes every one of two uses with just alcohol.
1 First thing to do is fill up a bowl with 2 cups of lukewarm water, it's very important not to use warm or hot water for two reasons, 1 the alcohol will evaporate and 2 hot water can loosen the glue holding the bristles together and attached to the brush ferrule.
2S2 Secondly add 1 tbs of dishwashing liquid, I don't have a specific brand I just use water is in the kitchen. Add 1/4 cup of Alcohol, I use 91% because it's the strength I use to spot clean my brush.
The last ingredient in this little concoction is coconut oil but you can also substitute it with Olive or Almond oil. The oil really helps in my foundation brushes the most because it's great at breaking down the makeup. I only use a dime size amount or 1/2 tsp because too much can leave the brush greasy.
3 After all the ingredients are in the bowl you can start cleaning!
I just give the brushes a dip in the mixture then massage them against the palm of my hand and once I've done that with all of them I give them a final rinse in the sink with lukewarm/cool water.
I rest them upside down to dry. Its very important not to dry them in a upright or even sideways position as it allows water to sit at the base of the bristles and loosen the glue.
If you prefer a ready made brush cleaner my favorite is TheBodyNeeds2, it's absolutely amazing I used it on my beauty blender and it was as neon pink as when I first purchased it!