Cleaning your brushes can either be a pretty toxic process (think fumes from turps) or a costly one; environmentally friendly brush cleaners are expensive! It's a necessary evil for artists, however, especially us oil painters. Luckily, there's a cheap (and easy!) process for cleaning your brushes that won't have you in a coughing fit nor break the bank.... let me introduce to you, your new best friend....
Brh-duh-daaah! Soap to the rescue!
SOAP!
Yes, that's right. Not some secret magical product. Not special soap especially for oil paint. I personally just use Palmolive's bar soap, which I can get 4 bars of at my local shop for €1.50 (about $1.70).
BEST METHOD
Before cleaning, I'll generally wipe the brush on a rag or paper towel to get as much paint as I can off the brush before I start. I swirl the brush around the bar under warm water to get the paint out, rinsing the brush after a few swirls once it's full of soap. I repeat this a few times until no colour comes out on the soap when I'm swirling it. Then, on the bar of soap I gently brush the bristles back into place so that the brush is in perfect shape again, rinse off and leave to dry; I use an instant coffee jar to keep them upright, bristles facing up. I find this method not only leaves my brushes perfectly clean, but also helps the brushes keep their shape (ever had a brush go a bit wonky after leaving it bristles-down in turpentine?) because the soap is great for reshaping the brush after cleaning. It's also handy and takes less than a minute per brush, depending on how much paint is on them. Check out the quality of my two favourite brushes after about half a year of painting (plus a few times of forgetting to clean them for a day or two after painting- nobody's perfect!):
My beauties fresh after cleaning
Notably, other bars of soap will do the trick, I just generally go for the cheaper option that's readily available to me, and I encourage you to do the same. It's also worth noting that I use golden synthetic brushes, but if you use expensive brushes with delicate bristles (such as sable hair) and you're concerned about harsher soaps affecting the bristle quality, you can use a soap that's designed to be more mild on the skin and unscented, or a gentle shampoo (such as baby shampoo) and swirl it on your hand.
Keeping your brushes clean can be an annoyance, but this method saves it from being an annoyance to your wallet and health at least! Happy painting!