Final answer:
The recommended product for tinting back to natural hair color from a lighter color is demi-permanent hair color due to its ability to darken hair and blend grays without causing excessive damage.
Step-by-step explanation:
When performing a tint back to natural hair color from a lighter color, the recommended product to use is demi-permanent hair color. Demi-permanent hair colors are ideal for this process as they are less damaging than permanent hair color and do not contain ammonia, which means they do not lighten the natural pigment of the hair. Unlike semi-permanent hair color, which washes out after several shampoos and is not designed for complete gray coverage, demi-permanent hair color lasts longer and can blend gray hair more effectively.
While permanent hair color is used to change the hair's structure and is necessary for lightening hair or covering grays entirely, it is not always required when returning to a natural shade from a lighter tone. Demi-permanent colors are often used to darken hair, add shine, and enhance the natural pigment without the commitment of a permanent change. The outcome will look more natural and will cause less damage to the hair. Moreover, due to the gentle nature of demi-permanent coloring agents, they can also be a better choice for maintaining hair health.