Good question ... I use this It's a asian rice bowl Like this one I picked up two at the goodwill for $1. the base makes it easy to hold and the higher sides hold the lather in nicely.
Not in my experience. Been using one for a couple of years and my badger, boar, and synthetic brushes are doing fine. Tapatalk Via Kyocera
Addendum; I assume by Japanese Bowl, you are talking about a Suribachi. It's a ceramic spice grinding dish made with an unglazed inner surface and a texture designed for grinding sesame seeds and the like.
That's just funny. Though I'm a little claustrophobic and use to be badly acrophobic, but had to do roofing for years and got over that.