New jeans are often stiff and dark coloured. They tend to run in the wash and can ruin other clothes. Also, the fad of the day is always changing and faded denim is sometime more fashionable than dark jeans. Lightening denim fabric can always be done over time in the wash. Washing denim over and over in warm water will leech a lot of the colour out and fade it. However, there are quicker ways to achieve the shade you want in your denim fabric.
Wash your jeans with bleach. Add 1 qt. of bleach to the wash water and let it agitate to mix in the bleach.
Add the jeans to the washing machine.
Wash as usual. This is a classic way to lighten denim fabric, but be warned it will also weaken the fabric. It is best to do this just the one time to avoid stressing the denim, which can cause holes.
Hang the jeans to dry or give them a light tumble in the dryer and finish by hanging. If you have the shade you want, dry clean or wash with Woolite to keep the denim from further fading.
Wash the denim in lemon juice concentrate, which is filled with acidity that fades colours. Fill your washer and add 1 qt. of juice. Let it agitate for a minute to incorporate the juice further and expose all sides of the denim to the solution.
Turn off the machine and add the denim. Let it sit in the lemon water for two hours.
Turn the machine on to agitate a few times during the wait. The goal is to get each part of the denim soaked in the water so you don't end up with dark spots.
Set your washer to rinse/spin and remove the water. Restart the machine and wash the denim as usual. Hang dry or lightly fluff in dryer and hang dry the rest of the way
Rub sandpaper on the jeans. Get the roughest grit you can and rub just in spots or all over. You can do this with the denim laid out on a table or you may want to put on the jeans if you just want fading in spots.
Rub everywhere for all-over denim fading. The rough grit sandpaper should be abrasive enough to fade the jeans without scrubbing. A light touch is preferred, as you don't want to sand through the fabric and make holes.
Wash the denim normally. The new factory dye will leech further in the wash giving you a final faded look. Sanding the denim made much of the indigo dye come out and opened the fibres of the denim. You get the added bonus of softened fabric.