What should you do if a client with red highlights wants to return to her natural brown color?

When a client with red highlights desires to return to her natural brown color, the best approach is to use a tint back with a green base color. This is because red is opposite to green on the color wheel, which means green can effectively neutralize unwanted red tones. By applying a green-based tint, the red highlights will be toned down, allowing for a more balanced and natural brown result.

This method considers color theory, which plays a crucial role in achieving the desired hair color outcome. Using a green base color can help in minimizing the visibility of the red highlights and bringing her hair back to a more natural brown.

The other methods outlined are less appropriate in this case. A bleach wash could further lightening the hair, which might intensify the reds rather than neutralize them. Using a blue base color may not be as effective since blue typically neutralizes orange tones, and the predominant concern here is removing and toning down red. Applying a color remover first could be an option, but it might not provide the precision needed for a return to brown without additional steps, such as re-tinting to achieve the exact desired shade.