Which factor is essential for achieving long-lasting results with hair color?

The factor that is essential for achieving long-lasting results with hair color is proper pH balance. Maintaining the appropriate pH level in both the hair and the coloring products is crucial because it affects the cuticle's ability to open and close during the coloring process.

When hair is at the correct pH level, it ensures that the cuticle remains healthy and can effectively absorb the color molecules. If the pH is too high or too low, it can result in improper color absorption, leading to faster fading or uneven results. Products formulated with a balanced pH help maintain hair health while ensuring that the color penetrates deeply and holds effectively.

Other factors such as hair texture, length, and scalp type may influence the application technique or the choice of products, but they do not directly impact the chemical process of color retention and longevity like proper pH does.