To remove pen stains on a white cotton cloth, dab with an ear bud moistened with lemon juice
On wool or white cotton fabric, dab the stain with a white cloth dampened with acetone, surgical spirit, methylated spirits or lemon juice
On other fabric, remove these stains with a mixture of equal parts of white vinegar and methylated spirits.
You can also dab the stain with a cloth soaked in hot milk. Repeat this process until the ink disappears.
Hair spray is also very effective at removing pen stains. Once the ink starts to foam, sponge and rinse thoroughly.