How to remove yellow stains from travel shoes

Travel shoes are yellow, and the method to remove them is as follows:

The shoes already have yellow spots or gray spots. If you want to remove these stains, you can first mix potassium permanganate with a ratio of 1:2 Soak the stain in water at a ratio of 1:10 and apply it on the stain. When the stain turns light yellow, use another brush to dip a dilute solution of oxalic acid and water in a ratio of 1:10 and soak it in the solution. Then rinse away the oxalic acid and wipe it with a soft cloth. Once dry, stains can be removed.

If it still can’t be eliminated, just pay attention when brushing other white shoes in the future. Shoes will turn yellow easily if washed with washing powder. Use soap to brush and cover with toilet paper after brushing. Do not even use shoe powder. It will be as white as new. In addition, this has something to do with the local water quality.