How do you care for the milk glass bowl that Tabac (and others) shaving soap comes in? Surely it isn't dishwasher safe? Or is it?
That bowl has a dome in the bottom where the soap rests on leaving a huge void underneath where moisture accumulates and forms a soapy soup like goo. That can't be good and I never understand why it's made this way instead of using just a flat bottom.
I wouldn't worry about it. just leave the soap in and forget about what builds under it. If it bothers you that much, however, then take the soap out and pour in some hot water to sit there for a while.
Why would you put this in a dishwasher? Just wash it by hand under hot water with or without a little dish detergent.
You can scrub it like you would a glass of wine or a porcelain dish.