I've got some white Birkenstocks. They look almost brand new on the outside of them despite me wearing them a lot this year. But the sole of them are looking a bit manky...the inner sole where your foot sits. It is marked with almost a dirty imprint of my foot and because they are light soles it shows up badly.
How do I clean that bit, or is it impossible? Has anyone done this? Do you think i could risk them in the washing machine?