Introduction: Save Your Paintbrush in the Paint Can
The proper way to wash a brush is first with solvent if it's an oil-based paint or varnish, then with soap or shampoo and water.
It is hair after all.
No one actually does this. In practice people wrap the brush in a plastic bag and pretend they'll clean it tomorrow. Some time later they throw it away.
Here's a better method. Just leave the brush in the paint can. It'll stay good as long as the paint does.
This is what commercial painters do with their brushes, rollers, etc.
We have a be nice policy.
Please be positive and constructive.