I soak mine while I shower, regardless of being boar or badger. I have learnt that one should, in order not to break the hairs(?) It also adds softness to the skin feel, of course.
I use synthetics most of the time and don't pre soak the brush, just run it under the water until it is warm. This may be why I sometimes have a problem with boar/badger brushes being dry when I go to make lather so I will try soaking them first and see what happens.
