Machine washing is rarely advised for any shoes, for canvas, leather
and fabric shoes machine washing can seriously damage them. Wet
shoes should be left to dry naturally. If you are drying shoes by
artificial heat it can separate leather and other materials from
their bonding. Again this can cause serious damage which cannot
be repaired. When scrapping dried mud from your shoes use a brush,
a sharp or dull knife can create deep scratches in the leather.