Which colour tool is commonly used to apply colour products with a liquid consistency?

The applicator bottle is the correct choice for applying colour products with a liquid consistency, such as hair dye or other color treatments. This tool is designed with a narrow nozzle that allows for precise application, ensuring that the product can be directed exactly where it is needed on the hair. The fluid consistency of the color products makes the use of a squeeze bottle ideal, as it provides controlled delivery of the product without making a mess.

In contrast, a color mixer is primarily used for blending color formulations but does not apply the product to the hair. Foils are typically used in highlighting techniques to separate sections of hair and to keep the color processing away from other areas, but they do not apply the color themselves. A spatula, while useful for mixing or applying creams, is not typically suitable for controlling and delivering liquid products effectively. Thus, the applicator bottle is specifically designed for the task at hand, making it the most effective and appropriate tool in this context.