After cleaning a brush with thinner, you’ll notice that the heavier solids eventually settle to the bottom and leave the clear thinner at the top. Here’s a trick that will allow you to put that solvent to good use again and create a handy brush cleaner while you’re at it. Cut off about the top third and spout of a half-gallon milk jug, leaving most of the handle intact. Fill it partway with thinner and soak your brush as usual. Then go ahead and set the jug aside and wait several hours. When the thinner separates, use the jug like a funnel to pour the solvent off into a storage container, leaving the solids behind.