Cleaning oil-based paint out of your brushes leaves you with a murky pool of paint thinner or other solvent that you must somehow dispose of. Dumping it down the drain or tossing it in the trash is unsafe and often illegal, since thinner and mineral spirits contain VOCs (volatile organic compounds), toxic chemicals that are dangerous to humans and the environment.
Try this tip to help you skip the trip to your nearest hazardous waste facility—plus the one to your local home center for more paint thinner.
Create a Dedicated Container
It turns out that the solvent you used to clean your brushes or roller covers can be reused. So the first thing needed is a container for the reclaimed liquid. The container the paint thinner came in works, whether it’s the gallon-sized plastic bottle or rectangular, quart-sized metal can. (You’d just need a small funnel to get back in the can.) Otherwise, any heavy plastic bottle with a tightly fitting lid will do, such as a cleaned-out plastic applesauce or peanut-butter jar. Clearly label your reclaimed solvent bottle with a strip of masking tape and a Sharpie.
Reclaim the Paint Thinner
After you’ve cleaned your brushes, let all the murky material in that dirty pool of solvent settle at the bottom of your cleaning container. This may take a day or two sitting undisturbed in a garage or other location, where fumes will not ignite or pollute your home’s indoor environment.
Then, pour your relatively clean solvent off the top into the used paint thinner container (using that funnel, if necessary), leaving the collected residue at the bottom of the old container. Tightly cover and store with your painting supplies, where it will be ready to clean more paint brushes and roller covers in the future.
Prepare Residue for Disposal
Before you can trash that layer of sludge at the bottom of your brush-cleaning vessel, you must allow the remaining solvent to evaporate. Use the same care in choosing a location for this as when you were letting the sediment settle, as this sludge produces the same fumes that can ignite or pollute the air in your home. Once completely dry, the container can be thrown away in your common trash receptacle.
Reusing your brush-cleaning solvent hits the trifecta: Benefiting the environment, costing you a little less money and saving time and effort. In our book, that’s a win.