A package (10) for storing and dispensing a flowable material includes a container body (11) having an inlet end (20) and an outlet end (21). The container body (11) is configured to hold a quantity of the material and has a piston (30) receivable within the inlet end (20) and movable within the container body (11, 12). At least a portion of the piston (30) is selectively permeable to a selected medium.
