Updated: a day ago
Caution! All oil, oil paint, and solvent-soaked rags/paper must be disposed of in a sealed metal container or fire may occur. Special containers are sold for this purpose.
1. Wipe paint off brushes with newspaper, paper towels, or rags.
2. Emerge wiped brushes in mineral or baby oil that is at least 2 inches deep. The primary ingredient (98%) in baby oil is a highly refined/food-grade mineral oil that costs less than 20 cents per ounce…if purchased by the gallon.
3. Agitate brushes to loosen paint. Some people stir the brushes in a figure 8. You can go to the next step now or wait a few days depending on your time schedule.
4. Wipe oil off with paper towels. A non-lint paper towel like Viva or the blue shop towels and lint-free rags are all great.
5. Rinse with paint thinner or a dish soap like dawn brand, but you must decide if you want the brushes cleaner with solvent rinse, or whether you want to continue with a nontoxic method using dish soap and water. If you clean with paint thinner solvent, do this in a well-ventilated area, preferably outside. I recommend that you clean with solvent at least every few months to keep any residue paint from hardening.
6. Wipe brushes dry then lay brushes down at a slight angle so the remaining cleaner runs out away from the brush’s ferrule. (Note: If using dish soap and water to clean, it may cause early deterioration of a wooden paintbrush handle but I do not find this a problem with better brands of paint brushes.)
7. Although the paint brushes will dry faster if you clean them in paint thinner, the brushes will smell for a few days. Because of so many synthetic fibers being used in oil painting brushes nowadays, I would not recommend using a hairdryer to quicken the drying time. Of course, “never” use a hairdryer if you've used a solvent like paint thinner for the final rinse.
8. Brushes need to be very dry to get their spring back.
9. Shape brushes: If the tips of the brushes are not as pointy as you like, use a little hairspray or basic hair gel on them. Then run your fingers over the tips to shape the brushes. In bad situations, you can put a thick paper over the brush and put a clip or hairpin on the tip to point the brush. This is not recommended for flat shapes. Also with synthetic brushes, you can dip them in very hot (not boiling) water, then dry and hang or lay them down to dry.