White like the first day: How to clean your tennis without using a drop of chemicals?

You walk like on a walkway, you take care of them more than your cell phone, and you even avoid puddles like quicksand. But inevitably, with the passing of days, dirt slips between the seams, stains appear as if they had a life of their own, and that pure white turns into a dubious tone that could be described as “grey Monday.” At that time, many of us run to chlorine, to powerful detergent or to those products with unpredictable names that prom…