Hair type and texture – for example curly or straight, fine or coarse – is a key consideration when colouring hair. The structure of each individual hair differs by hair type; finer hair has a smaller diameter and generally absorbs hair colour quicker, where thicker hair types have a larger diameter and absorb product slower. Hair that is chemically treated may also process faster or slower than hair that is not. L’Oréal Paris recommends following the directions on the Instruction Leaflet included in each pack of hair colour.