An apparatus (900) for transferring a viscous material, the apparatus comprising: a) a first container comprising a base (250) defining an inner mixing well (252) capable of containing a viscous material； b) a transfer piston insertable in the first container so that the piston forms a circumferential joint with respect to the inner mixing well (252)； and c) a mechanism (950, 256, 264, 952) for fixing an opening of an injection tank (910) to a hole in the transfer piston； characterized in that the inner mixing well (252) includes a groove (264) the base (250) includes outer threads (256)； The transfer piston comprises a piston bush (950) that includes the hole and internally facing threads (956) that couple the outer threads (256) on the base (250)； and because the apparatus further comprises d) a cleaning element (260) having coupling arms (262) that are configured to sit in the groove (264) in the interior mixing well (252)； wherein the insertion of the transfer piston into the first container releases the coupling arms (262) from the groove (264) and displaces the cleaning element (260) from the inner mixing well (252), thereby doing that the viscous material passes from the inner mixing well (252) through the hole and the opening into the injection tank (910).Un aparato (900) para transferir un material viscoso, comprendiendo el aparato: a) un primer contenedor que comprende una base (250) que define un pozo de mezclado interior (252) capaz de contener un material viscoso； b) un pistón de transferencia insertable en el primer contenedor de manera que el pistón forme una junta circunferencial respecto del pozo mezclador interior (252)； y c) un mecanismo (950, 256, 264, 952) para fijar una abertura de una depósito de inyección (910) a un orificio en el pistón de transferencia； caracterizado porque el pozo de mezclado interior (252) incluye una ranura (264) la base (250) incluye roscas exteriores (256)； el pistón de transferencia comprende un casquillo de pistón (9
