How does the oxidative coloring process work and what does "permanent" mean for maintenance?

Permanent hair dye like Rubella Fashion 5.0 works through an oxidative reaction. When you mix the coloring cream with the developer (hydrogen peroxide), small colorless precursor molecules penetrate the hair cuticle and reach the cortex. Inside, they react with oxygen and couple together to form larger pigment molecules that are trapped within the hair fiber. Because the color is created inside the hair rather than sitting on the surface, it does not wash out with shampoo.

What "permanent" means practically: the colored hair stays that shade until it grows out or is cut off. You will see regrowth at the roots — typically 1–1.5 cm per month — where your natural color shows. To maintain an even look, most people touch up roots every 4–6 weeks. The previously colored lengths do not need re-dyeing each time; reapplying only to new growth avoids unnecessary processing and keeps hair in better condition.

The final tone depends on your starting shade, porosity, and any previous color. On virgin hair, 5.0 typically yields a neutral light brown. On previously colored or highlighted hair, the result can vary — porous areas may grab more pigment and appear darker or cooler. A strand test on a hidden section helps preview the outcome before full application.