An applicator for the application of a product, for example a cosmetic or dermatological product, including a reservoir of which a first side is attached to a finger or mounted to a finger to face the finger. An applicator portion is arranged on a second side of the reservoir opposite the first, and the applicator portion is isolated from the reservoir at least before first use of the applicator. The applicator device further includes a device to establish communication between the reservoir and the applicator portion, for example, in response to an operating action at least during the first use of the applicator.