How do I properly perform a patch test and a strand test before using this permanent color?

Patch test (allergy/sensitivity check): Mix a pea-sized amount of color cream with an equal amount of developer in a non-metallic bowl. Apply a small dab behind the ear or on the inner forearm, cover with a breathable plaster, and leave undisturbed for 48 hours. Wash gently if needed. If any redness, itching, swelling, burning, or blistering occurs — even mildly — do not use the product. This step is mandatory if you have a sensitive scalp, history of reactions to hair dye, or have not colored your hair in over six months.

Strand test (color and hair condition preview): Using the same mixed formula, apply to a few strands from a discreet area (nape or underneath layer). Time it exactly as the instructions state for your desired result. Rinse thoroughly with lukewarm water until water runs clear, apply the provided post-color conditioner or a gentle mask, then air-dry. Assess: is the shade what you expected? Does the hair feel elastic and smooth, or brittle and rough? If the strand snaps easily or feels gummy, the hair is too compromised for permanent color right now — consider a semi-permanent or professional treatment first.

Do both tests every time you buy a new box, even if you've used the same shade before; formulations and your own scalp condition can change.