Can I use this on hair that has been bleached, highlighted, or chemically straightened?

The product information explicitly advises extra caution if your hair is very damaged, freshly bleached, or chemically processed. Bleached or highlighted hair is highly porous, which means it can grab pigment too aggressively, leading to a darker, flatter, or even greenish cast on a black shade, and the color may fade unevenly. Chemically straightened or permed hair already has altered protein structure, so the additional alkaline process of permanent dye can increase brittleness. If you still wish to proceed, perform a strand test first: apply the mixed dye to a small hidden section, follow the full timing and rinsing steps, then evaluate the result and hair condition after drying. The fixing balm with keratin and vitamin complex helps smooth the cuticle and restore some manageability after coloring, but it cannot reverse pre-existing structural damage. If the strand test shows excessive dryness, breakage, or an off-tone result, consider a semi-permanent or deposit-only formula instead, or consult a professional colorist for corrective work before applying permanent black.