What effect can shampooing before a color application have?

Shampooing before a color application primarily serves to remove any product buildup, dirt, or oil from the hair. While the presence of natural oils can provide a barrier that protects the scalp, washing the hair ensures that the color will adhere properly and penetrate the hair shaft effectively. By eliminating oils and residues, the hair becomes a better canvas for the dye, which allows for a more even application and potentially better color results.

However, removing these natural oils can also mean less protection for the scalp, making it more susceptible to irritation from the color product. This is why it's crucial to consider the balance between clean hair and scalp protection when preparing for hair coloring.