If you want to keep sharpie ink on your clothes for a longer time, you need to follow some suggestions. Firstly, you should immediately iron the area written with sharpie. You will have to make sure that the piece of cloth remains dry for about 5 to 6 hours at least. Now, you may hand-wash that cloth with a mild shampoo. Spraying a hairspray over the ink is another good option. You should not bleach your clothes as it lightens the sharpie ink.