A three step system for cleaning oil painting brushes without the use of toxic solvents.
Step 1: Carefully remove as much oil paint as possible by squeezing the brush between folds of a lint free paper towel. My favorite paper towels are the blue shop paper towels from Home Depot.
Step 2: Swish the brush in the Silicoil jar containing 85% shampoo and 15% water. The pigments fall away from the brush hairs to the bottom of the jar. Periodically wipe and swirl the brush on a clean part of the paper towel. (I use Everyday Shea shampoo because it does not contain a lot of additives that are harsh on the brushes like SLS, or silicone that could coat the brush hairs and end up in my painting.) The shampoo works really well. After all, shampoo is designed to remove oil and dirt from hair.
Step 3: Under running water, swish the brush back and forth on the bar of da Vinci soap until no more pigments are visible on the brush and soap. Dry the brush on the paper towel and shape the tip. Lay flat to dry.
I've tried a lot of soaps over the years. Ivory, though touted as very gentle, damaged the finish on the handles of some of my favorite brushes. Escoda, Irish Spring and Master's Brush Cleaner and Preserver in the tub didn't seem to clean all the oil out of the bristles. The daVinci brush soap is more expensive than a lot of other soaps but I find that it removes the oil completely while being very gentle on the brush. With the daVinci soap I don't end up with hardened brushes or wear them down prematurely. Finally, a perfect combination.