Device for treating the hair for controlling the application of a product

Device for treating the hair, comprising:

• two arms that are able to move relative to one another between a moved-together configuration for treating the hair and a spaced-apart configuration for inserting hair to be treated between said arms,
• two heating elements that are each intended to come into contact with the hair and are each disposed on an arm, and
• an application system for applying a cosmetic product, comprising a holder and a refill which is mounted on the holder and comprises an applicator member made of a porous material and being soaked with the cosmetic product for applying the cosmetic product in a liquid form on the hair while contacting the hair in the moved-together configuration of the two arms, the application system being mounted on one of the arms, and the holder being able to move relative to said arm between at least two positions generating, while the two arms are in the moved together configuration, different respective application pressures of the applicator member on the hair to be treated,
• the arm opposite to the arm on which the application system is mounted comprising a counter bearing surface such that, in at least one position of the holder of the application system, the hair is pressed against the applicator member with a certain pressure by the counter bearing surface while the device is being used to treat the hair,
• wherein a surface of the applicator member configured to contact the hair being continuous.