The working surface of a thin material (e.g. textiles, paper, foils, plastic films) in a continuous-feed process. In the printing and coating industries, for example, the web is spooled off an unwind shaft, passes through coating and/or printing heads, drying ovens, treatment stations, and slitting knives, eventually to rewind on the finished roll. A web break is a minor catastrophe, as the loss of tension on the material will lead to application of too much or not enough coating, and misalignment through coating and slitting stations.