Here is the absolute best paint brush cleaner recipe known to man:
I take a sherbet-sized plastic container filled 2/3 with water and I add 2-3 drops dishwashing liquid.
Now the secret ingredient: Add I Tbsp. of liquid fabric softener. Mix together (it will take 30 seconds or so for the fabric softener to mix nicely in the water)
Now, take your brush (which you should have already scraped much of the paint off into the can) and dip into the "Wonder-Mix" (I just made that up). Swirl it around, then put your hands in and watch the paint simply disappear from the brush.
See, the laundry softener is a surfactant and pulls paint right off the bristles. Now, remember, never put the metal ferule of the brush in the water or you will have a rust problem.
To clean a 6 inch brush, it takes about 1 1/2 minutes. Rinse the brush in cool water, lay flat on a fluffy work towel to dry and feel the softness of your hands.
Next time you use this brush, the bristles are super soft and will hold more paint without dripping, another benefit of a surfactant.
I've washed plenty of rollers in the exact same proportioned mix, but used a higher bowl and had to dip both ends in the mix - the the paint simply said "bye bye". Isn't it nice not to use those nasty chemicals or spend 2 hours rinsing and rinsing your brush until your hands are all wrinkly and dried out?
Source: I've been painting for years and have tried just about everything to make this tedious task less awful. Then I fell into this. It was a total accident. I thought I'd put liquid clothing detergent in the mix - then found out if was the 99 cent fabric softener!