Use an old fork to clean a paintbrush. They're good at getting between the bristles and whisking out every last drop. thisoldhouse.com Photo: Wendell T. Webber | thisoldhouse.com | from Best of 10 Uses for Common Household Products
When using latex paint, you can use a product called Floetrol (affiliate link). You add a few tablespoons to your paint and it's basically like a conditioner for your paint that leaves barely any brushstrokes behind.
Paint Brushes For the artistic variety, by dipping the bristles of a paintbrush into a hardening resin, here is another common household product that is now serving an entirely different function than it was originally intended.
Save a Dried Up Paint Brush Soak it in a cup of vinegar until the bristles loosen up. Then wash it in warm, soapy water. Still stuck together? Boil it in vinegar for 10 minutes and follow up with another soapy water bath.
At about $10 apiece, paintbrushes aren’t disposable. On the contrary, quality paintbrushes can be of service over and over. If your synthetic-bristle brush is caked with dried paint, you can restore its usefulness with a good long soak in vinegar. Let the brush sit in the liquid for a couple of hours, then proceed to wash it with warm, soapy water. Once done, you should find that a salvageable brush will have returned to pliability.