How can I maintain the dark brown shade and keep hair condition good between colorings?

Permanent color fades primarily through shampooing, heat styling, and UV exposure. Switch to a sulfate-free shampoo formulated for color-treated hair; sulfates strip the lipid layer that holds pigment. Wash with lukewarm or cool water — hot water opens the cuticle and accelerates color loss. Limit washes to 2–3 times per week; dry shampoo on off-days extends the interval. Once a week, apply a rich hair mask (the same type of conditioning base used in this dye or any deep-conditioning treatment) for 10–15 minutes to replenish lipids and keep the hair glossy. Before blow-drying or using hot tools, apply a heat-protectant spray; excessive heat oxidizes the dye molecules, turning brown tones brassy. In summer or during holidays, wear a hat or use a leave-in product with UV filters — sunlight breaks down both natural melanin and artificial pigment. If the roots become visible before you want to re-color the full head, use a root touch-up powder or mascara for a temporary fix rather than overlapping permanent dye on previously colored lengths, which causes uneven darkness and damage. Schedule full re-application every 5–7 weeks depending on regrowth speed, and always repeat the allergy test each time.