Abstract: The present invention relates to a preparation method of a paste by mixing at least one constituent substance in a solid form, notably a powder, with at least one constituent substance in a liquid form, mechanically kneading the mixture under vacuum and subjecting said mixture to vibrations under vacuum.According to the invention, the mixture is subjected to a vibration field during at least the final phase of the mechanical kneading in a device comprising a base (2), a bowl of revolution (28) carried by said base, a cover (21) closing said bowl in a tight manner, an evacuation duct (10) opening into the bowl and kneading blades (27), the bowl being suspended underneath the cover and removably connected to said cover with means (11a, 11b) for imparting vibrations to the cover and bowl assembly via the cover.The present invention applies to the preparation of alginate, plaster or similar substances based pastes.