How important is it to clean your oil brushes? And what's the best way to do it? I suppose painting everyday would take care of it. The paint in your brushes wouldn't have time to dry and ruin your bristles. The problem with just rinsing your brushes in turpentine is that turpentine, paint thinner, turpenoid or any mineral spirits leaves your bristles brittle. There are oily paint thinners that soften your bristles but they are not good for thinning your paint while painting. Plus the smell is very strong which tells me it is toxic to some degree. , a Gamblin product, is non-toxic and has no odor. About twice a week at the end of a day I rinse the brushes out very well in Gamsol. This should get the paint out of the bristles. I then use Dawn dish detergent and wash the Gamsol out of the brushes which keeps them from getting brittle. You can always dip the brushes in walnut oil or lard to keep the brushes suple. If you paint a lot your brushes will probably wear out before you have to do much washing.