In this paper temperature measurements and simulations were carried out to understand the mechanisms of copying curl. Normal copy papers were studied, but special handsheets with built-in thermocouples were also used. A drying simulation program was used to show the temperature and moisture profiles inside paper in thickness direction. Results show, that during the nip the moisture moves towards the press roller side and then more moisture evaporates from the side which was in contact with the press roller, as it became more wet during the nip. At high speed, there is not enough time for even moisture distribution inside the paper sheet, as it happens at low speed. Curl phenomena in this case can be explained by difference in temperature and evaporation rate on two sides of paper sheet (PDF) Temperature measurements and simulations inside a paper in a fuser nip.