A method of operating a filter press for solid-liquid separation of a product, the filter press comprising a press jacket with an end, and a ram in the press jacket and movable relative to the end to define a pressing space. The method comprising loading a product to be pressed in the pressing space; positioning the ram in a start position so that the product only partially fills the pressing space; advancing the ram, during a first phase of a forward movement, from the start position to a full contact position where the volume of the pressing space becomes equal to a volume of the product; and advancing the ram toward the end from the full contact position during a second phase of the forward movement, the ram exerting no pressure on the product during the first phase but exerting pressure on the product during the second phase to press liquid phase out of the product. At the full contact position, the ram is advanced at a forward velocity lower than an average forward velocity over the first phase.