Many old maps have been removed from atlases. Often such maps have a vertical fold down the center. Opening and closing the atlas often results in a weakening of the paper at the centerfold, frequently necessitating repair. Browning tends to occur at the centerfold because the paste used to hold the map in the atlas attacks the paper.
The type of film used on an L-Sealer Machine. The film is a web which has been folded in half as it is wound onto the core, allowing for an upper and lower web of film between which the product is placed for sealing on an L-Sealer Machine.
The centerfold of a magazine refers to a picture printed on a single sheet of paper and inserted in the middle of the publication. Since magazines are usually stapled together along the spine, the centerfold does not have any gutter cutting through the image. Centerfolds are also frequently much larger than the publication and then folded to fit.