Question: how long do you have to wait to dye your hair after washing it?
Answer: It's best to shampoo 12-24 hours before coloring with a Semi-Permanent (lasts through 8-12 shampoos) or Demi-Permanent product (lasts through 28 shampoos); shampoo 24 hours prior to using Permanent color (lasts until your hair grows out or you recolor).