I found a technique that works pretty well to accelerate break-in.
- Soak the brush bristles overnight to get them thoroughly saturated. Room temperature is fine.
- Take your least expensive soap and palm lather to build up a large amount of lather.
- Rinse, hang to dry for at least 24 hours. Going from wet to bone dry helps the bristles to split.
- Repeat above steps four or five times. Now, the brush should be soft enough to use for face lathering.
- Finish break-in by using the brush normally.