How should I apply it on light, bleached, or mostly gray hair to avoid an overly strong result?

If your hair is bleached, highlighted, very light blonde, or more than 50 % gray, the cuticle is more open and will take up pigment quickly. Start with a strand test: apply a small amount to a hidden section, leave it for just one minute, rinse, and check the tone. If the plum looks too intense, you have two practical levers. First, cut the leave-on time to 30–60 seconds for subsequent full-head uses. Second, dilute the colour shampoo 1:1 or 1:2 with your regular mild shampoo in your hand before applying — this spreads the pigment more thinly and gives a softer, more controllable deposit.

Apply on wet hair, distribute the foam evenly from roots to ends, and watch the colour develop in the mirror rather than relying on a fixed timer. Rinse as soon as the tone reaches the level you want; you can always reapply a few days later to deepen it, but you cannot easily remove excess pigment without a clarifying wash or a salon visit. After rinsing, follow with a conditioner or mask to close the cuticle and slow down fading. Avoid using the product on the same day as a chemical service (perm, relaxer, fresh bleach) because the hair surface is already compromised and may grab colour unevenly. If you have a sensitive scalp or known contact allergies to hair dyes, do a patch test 48 hours before first use and consult a specialist if you are pregnant, breastfeeding, or under medical treatment for a scalp condition.