Which aspect is NOT affected by the color of a client's natural hair when choosing a dye?

The density of the client’s hair does not directly impact the choice of dye in terms of the hair's color characteristics. Density refers to the number of hair strands on the scalp and how thick or thin the individual hair strands are. It primarily affects the overall fullness and appearance of the hairstyle rather than influencing color selection.

On the other hand, the base level of a client's hair, the undertone of the hair, and the desired final color result are all significantly influenced by the natural color of the hair. The base level determines the starting point for any coloring service, the undertones can add warmth or coolness to the final dye result, and the desired final color will vary based on how these factors interact with the chosen dye product. Understanding these elements is essential for achieving a successful color application and ensuring the client's expectations are met.