Will this shade work on my current hair colour, and should I test it first if my hair is light or damaged?

The shade is formulated for a medium-brown to light-blonde starting base. On natural medium-brown hair it deepens the tone and adds a warm coffee richness. On dark-blonde (level 7–8) it shifts the colour toward a soft chestnut-brown with visible grey blending. On light-blonde or highlighted hair (level 9–10) the same pigments deposit much more intensely, often producing a noticeably darker, warmer result than expected — sometimes edging toward a red-brown rather than a neutral coffee. If your hair is heavily bleached, porous, or has had a recent perm, relaxer, or other chemical service, the cuticle is more open and will absorb pigment unevenly; a strand test on a hidden section (behind the ear or at the nape) for the full 10 minutes will show exactly how the shade develops on your hair. The same applies if you have a lot of grey: resistant grey strands may take the tint lighter than the surrounding hair, so checking a few grey hairs in the test helps you decide whether you need a longer processing time or a follow-up with a dedicated grey-coverage product. Always do the recommended patch test 48 hours before first use to rule out sensitivity, even if you’ve used other tinting shampoos without issues.