Lightening or completely bleaching out your denim jeans gives them a lived-in, worn look. Because of the complex dyeing process of denim, however, lightening or bleaching it involves more than simply placing your jeans in your washing machine's bleach cycle. For best results, combine a few different methods to remove as much of the colour from your jeans as possible before you try to bleach them.
Because the denim threads are so thick the cotton absorbs a lot of dye, which needs to be loosened up and removed before the bleach will have any effect on your fabric. Use a colour remover, which is available from most dye-making companies and usually is found in the laundry section at your local grocery store, to remove as much of the dye from the jeans as you can. As each colour remover works differently, read the directions carefully and follow the instructions exactly. Always use the maximum amount of colour remover recommended for best results with denim. You should see your denim fabric lighten up by at least two shades. If your jeans are any darker than a sky blue after this treatment, repeat the process until they are a sky blue colour. Rinse the denim in hot water until the water runs clear.
Many dye manufacturers make a product specifically for jeans that causes the fibres to swell and loosen, and this releases the dye and fades the jeans. You can find this product in either the laundry section of your grocery store or in the dye section of your local sewing or craft shop. After you remove as much colour from your denim as you can, follow the manufacturer's direction to fade the denim until it is at least a shade or two lighter than it was before you faded the jeans. Rinse the denim in hot water until it runs clear.
Set your washer on a hot-wash setting with the water high enough, so it will cover the denim entirely. Place one cup of bleach in the hot water and let it agitate for at least two minutes. Place the jeans in the hot bleach water and set your laundry on its longest wash cycle. Adjust the cycle time as it runs, so the jeans are submerged in the bleach for at least one hour. After an hour, let the washer continue through its rinse cycle.
Bleach often leaves a yellow tinge to denim, and many find this unappealing. If you want a whiter look to your denim, run the fabric through a cold-wash cycle with one capful of bluing, which you can find in the laundry section of your grocery store. Dry your denim when done.