Abstract: A method of mixing a composition in the liquid state comprises enclosing the compositin in a tube, locating the tube in tube location means rotatably mounted on a member, spinning the member about a spin axis, and for at least part of the spinning period rotating the tube location means about its own axis of rotation parallel to the spin axis and spaced therefrom, so that the tube is subjected to both spinning and end-to-end rotation.Apparatus for carrying out the method preferably comprises a sun and planet gear assembly which rotates on the spin axis, the tube location means being coupled to planet gear of the assembly so that rotation of the assembly causes the spinning of the tube, and relative rotation between the sun and planet gears causes the end-to-end rotation of the tube.