Abstract: To facilitate manual opening of a container made out of a flat material like paper, cardboard, etc. with a ridged-seam closure, and especially a parallelepipedal container for liquid and made out of paper, plastic, or composite, at least one tear-off flap is attached to the outside of the ridged-seam closure like a tab. To facilitate in particular the opening of containers with earfolds, perforations are provided in the vicinity of the triangular folds to generate a smooth tear when the container is opened and produce a clean opening that will ensure trouble-free pouring.

Abstract: In the steam sterilization of packaging material, such as blanks intended for containers of acid liquids, the improvement which comprises employing a packaging material with a surface germ-count of less than approximately 1 germ/dm.sup.2 and using steam at atmospheric pressure. The packaging material can comprise a reel of fibrous material coated on one or both surfaces with plastic or it can comprise plastic-coated containers. After steaming, it may be hot air dried.

Abstract: In a cardboard blank for a gas-tight and liquid-tight folding box, especially one printed externally, carrying on the cardboard surface which is to be the inside of the box a full-surface layer of heat-sealable plastic, the improvement which comprises an additional plastic layer positioned between the full-surface plastic layer and the cardboard, the additional layer being provided only over portions of the surface including the seam areas, the thickness of the full-surface plastic layer together with the local additional plastic layer being sufficient for tight, hot-sealed seams. The additional layer can be hot melt printed onto the cardboard, before application of the full-surface layer, at the same time the cardboard is printed and/or die cut. By providing the additional layer only in critical areas such as seams or fold lines, a thinner full-surface layer can be provided with an overall economy of plastic.