An adapter for a jar for use with a planetary mixer, the adapter securing a dispensing container having a body and a removable cap, the adapter having a central aperture through which a longitudinal axis of the jar passes when the adapter is inside the jar. When the dispensing container is secured to the adapter and the adapter is inside the jar: (i) the adapter maintains the container spaced from an inner wall and from a bottom of the jar; (ii) a gap is provided between a top of the jar and the container; (iii) a point on the cap of the container extends further from the bottom of the jar than does a point on the body of the container; (iv) the body of the container crosses the longitudinal axis of the jar; and (v) the container extends over more than half the diameter of the jar.