Brown hair is, in terms of prevalence, the second most common hair type in the world after black. It's a versatile colour with countless nuances, adaptable to all skin types, that adds value and personality to any cut. Unfortunately, brown hair is also susceptible to colour oxidation due to various factors such as heat styling tools, sun exposure, and pollution. All of these cause the appearance of unwanted red undertones in both natural hair and hair coloured with dark shades.