A method of preparing a cryogenic sample (e.g. for study in a charged-particle microscope), whereby the sample is subjected to rapid cooling using a cryogen, comprising the following steps: Providing two conduits for transporting cryogenic fluid, each of which conduits opens out into a mouthpiece, which mouthpieces are arranged to face each other across an intervening gap; Placing the sample in said gap; Pumping cryogenic fluid through said conduits so as to concurrently flush from said mouthpieces, thereby suddenly immersing the sample in cryogenic fluid from two opposite sides, wherein the flush of cryogenic fluid applied from a first of said mouthpieces is different—e.g. has a different duration—to that applied from the second of said mouthpieces.