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I know this sounds like a dumb question, but I am interested in any brush washing tips that help prolong the lifetime of my brushes.
Water-based paints are easy, but with paints that require thinners / white spirits things are a little trickier.
My personal method is to pour some white spirit into a small container, thoroughly 'swish' the brush around, then rinse it with hot soapy water. I repeat this around 3 times, with a clean tub of white spirits each time.
However, despite this, my brushes are still a little stiff when I come to use them next, and do not deliver the same even finish they did when new.