Hi;

In the kayak building profession, we all wear red pants, so this is an easy question. Get a 2-1/2 gal container of chlorine from a pool supply store. Remove your pants and place them in the chlorine. Cotton is recommended, as fabrics such as Lycra will only dissolve. Leave the pants in the chlorine until they are bone white. Any slight discolorations can later be removed with hydrogen peroxide, an oxygen bleach.

When the pants are white, shake catsup all over them. Put the pants back on and go to work. You will have to reapply the catsup every few months, when you wash the pants.

Hope this helps, Spidey