Boumy leather slippers can best be cleaned with a damp cloth. The slipper and boot styles can even be washed in lukewarm water. In this case however, you should add some fabric softener. After you have washed them, hang them up and let them dry (do not put them in a clothes dryer). Once the slippers are dry, it is advisable to rub some neutral shoe polish on them.
After the slippers have dried, they tend to be somewhat stiffer but they will become soft and flexible again after wearing them for a few hours.
You can also clean these with a damp cloth. It is recommended that you brush the slippers with a suede brush, after you have washed them.
The soles tend to become a little smoother after some time. In order to make them a little rougher again, you can brush them with a suede or steel brush, after you have washed them.