Silver refreshers require a sufficiently light base and precise cool-pigment direction, because porous hair can quickly shift violet, blue, gray, or dull.

Copper refreshers must balance gold, orange, red, and brown at the existing depth, with special attention to porous ends that can become too bright or too dark.

Red refreshers can restore vividness or change direction, so the plan must distinguish true red, cool berry, warm red, and deep red-brown while tracking porous buildup.

Brunette refreshers can restore depth or tone, but the plan must distinguish cool, neutral, chocolate, and warm brown while preventing porous ends from becoming too dark.

Color-depositing shampoo cleanses while adding surface pigment, so formula identity, wash frequency, lather distribution, dwell time, cumulative deposit, and removal must be tracked.