A cosmetic product includes a mascara composition and a treatment device, whereby the mascara composition is applied to the eyelashes by softening the mascara composition via heat. The mascara composition is solid at room temperature, however is softened at elevated temperature, so it may be applied to the eyelashes. The treatment device includes an applicator for receiving, heating to soften, and applying the softened mascara composition to the eyelashes. Once the softened mascara composition is applied to the eyelashes, the mascara composition is quickly cooled and thus solidified by the atmosphere. The mascara composition thus applied to the eyelashes provides a firm film covering the eyelashes, which is not softened at body temperature, and thus provides enhanced wearability. A cap detachable to the applicator is provided with a loading mechanism for delivering pieces of the mascara composition one by one to the applicator.