It is there for the life of the hair. Semi permanent color washes out significantly over the course of 8-12 weeks. However, semi-permanent color can permanently stain very damaged or porous hair, or gray hair. Redken Color Fusion and Shades E-Q are two products by Redken that actually improve the quality of your hair. Both leave deep conditioning agents in the cuticle of the hair shaft that increases the luster and softness.
Heavy conditioners coat the hair and prevent the color from penetrating completely.
When in doubt, call the toll free help number on the box if you have any questions.