What is a primary cause of hair color fading when using strong shampoos?

The primary cause of hair color fading when using strong shampoos is the alkaline pH. Shampoos that have a higher alkaline pH can open up the hair cuticle, which is the outer layer of the hair shaft. When the cuticle is raised, it allows color molecules that have been added to the hair during the coloring process to escape more easily. This leads to color fading more rapidly compared to using a shampoo with a balanced pH, which is formulated to maintain the integrity of the hair and the coloration.

In contrast, lower temperature, high humidity, and excessive conditioning do not primarily contribute to the fading of hair color. Low temperature generally refers to the heat applied during styling, which can affect the hair's moisture retention but does not significantly alter the chemical composition of hair color. High humidity can influence hair texture and frizz but does not have a direct impact on the chemical integrity of hair color from a shampoo perspective. Excessive conditioning may help in maintaining the hair's moisture levels and providing shine but does not address the pH balance necessary for preserving hair color.