White leather sofas, car seats, purses and jackets with the telltale blue streaks from denim are the result of a dye transfer. The strong blue dye from jeans or other denim products passes on to the white leather from friction; dry cleaning professional refer to this as a dye transfer. You can prevent this from happening in the future by spraying your white leather with a leather protector. You don't necessarily have to resort to using harsh chemicals that might ruin your leather. Instead, you can remove such stains with certain household items.
Place a generous amount of petroleum jelly on the stain. Rub it in with the back of a plastic spoon. Cover and saturate the stain.
Leave the petroleum jelly on the stain for two to three days. Allow the jelly to soak into the leather.
Wipe the petroleum jelly away with a soft cloth. First, wipe away the surface covering of jelly. As you continue to wipe, rub against the stain. It should wipe off very easily.
Wipe the stained area dry with a new, dry soft cloth.
Add a 10 pence-sized amount of leather conditioner to a soft cloth. Buff the area with the leather conditioner and the cloth. A good leather conditioner will not only moisturise the leather, but it will remove any remnants of dye. Allow the leather to air dry.