When you love the dark color of a new pair of jeans, you might be afraid to wash them for fear of changing the look. Denim certainly has a tendency to fade in the wash, but a vinegar soak combined with a salt wash can set the dye and keep your jeans looking new.
Soak and Wash
To set the color of your jeans, place the pants in a clean bucket. Pour enough white vinegar over the jeans so that they're completely submerged, then swish them around with your hands to make sure that all of the fabric is covered in liquid. Let the jeans soak for an hour, remove them from the bucket and wring them out lightly. Turn the jeans inside out and wash them in the washer with 2 tablespoons of table salt.