Piping: (1) In paper, the formation of ridges in a reel of paper left standing without a waterproof wrapper as the paper takes in or gives out moisture.(2)In film laminating over an ink film which is not perfectly dry.

• 管状故障:（1）卷筒纸当失去防水包装纸而存放一段时间后，会因吸入或放出水分而形成山脊似的情况。（2）裱胶时，胶层表面有着坚硬管状条子的情况。主要成因是油墨尚未干透而加工所致。