Like what you see? Ask us for a full-length preview and pricing options for our entire course catalog
Request full preview
Surface roughness or the amount of variation in the fabric surface is important because a rough surface can mark the surface of the sheet, especially if the sheet is wet. This negatively affects sheet appearance and can impact other sheet properties. Perhaps more importantly, especially on fast machines, a rough surface tends to carry more boundary layer air along with it. In unorun felt sections, as the sheet and felt approach a roll or can, this air can become trapped between the converging surfaces and cause the sheet to lift off of the fabric. In sections with open draws between the cans, this can cause sheet flutter in the pockets.