Question: how to unyellow white shoes?
Answer: Mix 1 tablespoon of baking soda with 2 tablespoons of white vinegar and a cup of water. Use a cloth or old toothbrush to scrub your sneakers until clean. Works on leather and canvas. This method also apparently works with 1 tablespoon baking soda and 1/2 a tablespoon of hydrogen peroxide/water combo.