Abstract: A vacuum cylinder is disclosed. The vacuum cylinder may be used in an envelope manufacturing machine, or machines for manufacturing other articles, to facilitate folding of articles about a preformed fold line, such as envelope seal flaps, during the manufacturing process. The vacuum cylinder has at least two rows of suction holes which are arranged at least substantially adjacent to each other and preferably overlap to a certain extent.

Abstract: A two-way envelope made up from a one piece blank comprising front and back panels joined along three sides thereof to form a container. A first sealing flap is joined along a perforated line to the free side of the front panel and a return sealing flap is joined along a first fold line to the free side of the back panel. The front panel is preferably larger than the back panel, and the front panel is formed with a fold line space a predetermined distance from the perforated line so that the distance from the outer fold line to the bottom of the front panel is greater than the distance from the bottom to the top of the back panel.The return sealing flap is inwardly folded upon itself to permit a larger return flap to be carried within the envelope during the first mailing. At least one crimped portion is provided in the return sealing flap to facilitate the handling of the flap by the first addressee.