begin at the hem of jean by twisting small sections and then putting elastic bands around the twists.
Once you have completed one side turn over the jeans and repeat technique on the other. (there shouldn't be much material left by now)
Pour bleach into your bucket and add some bleach to a spray bottle(You should probably wear gloves for this part)
dip the bottom of your shorts into the bucket making sure all the banded sections are in the liquid.
-This will need to be left for approx 20 minutes.
When you can see the colour has changed remove the shorts from the bucket and lay them in the bath. Use the spray bottle filled with bleach to spray the rest of the shorts. (This will help to blend in the two shades of denim)
Remove the elastic bands and rinse off the shorts with water.Put the shorts out to dry or if you are impatient like me pop them in the tumble dryer.