After decades of following the traditional instructions and washing my brushes after a good rinse I now do it by very thorough rinsing only, same as I've done for years with the paintbrushes I use with water-soluble paints.
A swish in one jar of white spirit doesn't cut it! You have to rinse in more than one container, preferably three or more. The final rise can be in brush cleaner or cellulose thinners instead of white spirit for a little extra oomph. So wipe the brush well, rinse drain rinse drain rinse drain in container #1, dry off, rinse in #2, dry, then rinse in #3, dry, reshape bristles and put brush aside to dry. The solvent in the last container should stay clean for
ages if you do the preceding steps properly.
The above works equally well with natural bristle (hog bristle and softer like badger and goat hair) and synthetics.
Foam brushes are widely considered completely disposable in the US, often used once and tossed in the bin, but that's only reasonable for pros I think. Foam brushes can be washed out and kept going same as foam rollers can, but don't expect them to last ages. And you have to be careful about rinsing them in brush cleaners as some solvents in the mix can dissolve foam.
transatlantic":cipg7mgw said:
Same with water based finishes. I find that even after washing with soap and water, it's not as flexible as when I first got it.
Sorry, probably obvious but you're not washing out long enough or thoroughly enough. This usually takes at least three latherings IME with paint brushes of the type I assume you're using because they have large internal reservoirs.
Best way to see just how well these reservoirs can hold on to traces of finish is after applying white paint, 10 minutes stood at the sink and you can still be seeing milky swirls come out of the brush when you fan out the bristles
Any wonder why some prefer to keep their brushes wet constantly!