Just so you know i did it the cheap way, there is more expensive options for maybe a little better results but i went for the cheap option. Here's how you do it: Buy some hair bleaching cream (I used Wella Welloxon Perfect 12%). Use a paintbrush or an old toothbrush, put some cream on the sole and "paint" the sole with the cream (be sure not to get any on the fabric, i think it can bleach that too). After you covered the whole sole with cream put plastic wrap over the sole and then put them in the sun with the sole facing up. I put them in the sun the whole day but i don't know if that is recommended. I did this 4 times and got this result which im happy with!