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You can use any colors you want, but darker and highly saturated colors will show up the best. This technique works best on blonde hair; markers probably aren’t the best choice if you have darker hair, but give it a try and see what results you get!  You can use a single marker color for this or dip-dye with multiple marker colors to get a rainbow effect. Washable markers are recommended, but you can try highlighters and other markers types if you want to experiment. This look usually lasts about a day. The washable markers will wash out of your hair very easily, even without shampoo. Keep this in mind throughout the day—rain and heavy humidity can cause the color to bleed, unfortunately.
Select your colors from a set of washable markers. Shampoo your hair to remove the color.