A method of using a cosmetic mask comprising the steps of: (a) providing a container system, the container system comprising a container, a closure, a strainer, and a mask compartment, wherein: the container comprises: a reservoir that contains a flowable product; and a threaded neck having an opening that leads to the reservoir; the closure comprises: a side cylindrical wall and a top; an inner surface having screw threads, and a circumferential lip above the screw threads; and an interior space that is defined by the top and the cylindrical side wall above the circumferential lip; wherein, the screw threads of the closure make a sealing engagement with the threaded neck of the container; the strainer depends downward from the neck of the container, protrudes into the reservoir, and comprises: a perforated cylindrical wall that has an inner diameter in the range of 25 to 210mm; a top end that is formed as a flange; a perforated bottom end; an interior space that is defined by the cylindrical wall and the bottom of the strainer, the height of the interior space being 25 to 50 mm; wherein: the mask compartment is a space that extends from the top of the closure to the bottom of the strainer; (b) providing a dry mask that has not been exposed to or treated with the same flowable product that is in the container; (c) removing the closure from the container; (d) placing the dry mask in the mask compartment, and reclosing the container; (e) inverting the container until the flowable product has saturated the mask; (f) returning the container to an upright position, and waiting at least several seconds or minutes to allow excess product to drain back into the reservoir; (g) removing the closure; (h) removing the saturated mask from the mask compartment; and (i) applying the mask to the skin. (a) providing a container system, the container system comprising a container, a closure, a strainer, and a mask compartment, wherein: the container comprises: a reservoir that contains a flowable product; and a threaded neck having an opening that leads to the reservoir; the closure comprises: a side cylindrical wall and a top; an inner surface having screw threads, and a circumferential lip above the screw threads; and an interior space that is defined by the top and the cylindrical side wall above the circumferential lip; wherein, the screw threads of the closure make a sealing engagement with the threaded neck of the container; the strainer depends downward from the neck of the container, protrudes into the reservoir, and comprises: a perforated cylindrical wall that has an inner diameter in the range of 25 to 210mm; a top end that is formed as a flange; a perforated bottom end; an interior space that is defined by the cylindrical wall and the bottom of the strainer, the height of the interior space being 25 to 50 mm; wherein: the mask compartment is a space that extends from the top of the closure to the bottom of the strainer; the container comprises: a reservoir that contains a flowable product; and a threaded neck having an opening that leads to the reservoir; a reservoir that contains a flowable product; and a threaded neck having an opening that leads to the reservoir; the closure comprises: a side cylindrical wall and a top; an inner surface having screw threads, and a circumferential lip above the screw threads; and an interior space that is defined by the top and the cylindrical side wall above the circumferential lip; wherein, the screw threads of the closure make a sealing engagement with the threaded neck of the container; a side cylindrical wall and a top; an inner surface having screw threads, and a circumferential lip above the screw threads; and an interior space that is defined by the top and the cylindrical side wall above the circumferential lip; wherein, the screw threads of the closure make a sealing engagement with the threaded neck of the container; the strainer depends downward from the neck of the container, protrudes into the reservoir, and comprises: a perforated cylindrical wall that has an inner diameter in the range of 25 to 210mm; a top end that is formed as a flange; a perforated bottom end; an interior space that is defined by the cylindrical wall and the bottom of the strainer, the height of the interior space being 25 to 50 mm; wherein: a perforated cylindrical wall that has an inner diameter in the range of 25 to 210mm; a top end that is formed as a flange; a perforated bottom end; an interior space that is defined by the cylindrical wall and the bottom of the strainer, the height of the interior space being 25 to 50 mm; wherein: the mask compartment is a space that extends from the top of the closure to the bottom of the strainer; (b) providing a dry mask that has not been exposed to or treated with the same flowable product that is in the container; (c) removing the closure from the container; (d) placing the dry mask in the mask compartment, and reclosing the container; (e) inverting the container until the flowable product has saturated the mask; (f) returning the container to an upright position, and waiting at least several seconds or minutes to allow excess product to drain back into the reservoir; (g) removing the closure; (h) removing the saturated mask from the mask compartment; and (i) applying the mask to the skin.