Abstract: The calendering occurs in a press nip of a calender with application of pressure, moisture and heat. To achieve a desired surface quality, the surface of the paper or cardboard web which is to be calendered is brought in the press nip to a condition above the glass transition curve of the materials. Prior to expiration of 20 to 60 milliseconds, the surface of the paper web departing from the press nip is subjected to a transition step by virtue of a cooling device first in combination with a change in moisture content to a condition beneath the glass transition point of the material. The cooling can occur during contact of the surface to be cooled with a cooled surface or by direct contact with a cooling, preferably inert gas. After calendering there thus arises a diminished increase in the roughness of the paper web, so that the surface quality obtained in the press nip is predominantly retained. There have been illustrated suitable apparatuses for carrying out the method.

Abstract: Calendering takes place in a calendering zone which operates under pressure with application of temperature and moisture. The desired smoothness is achieved with a correspondingly long dwell time of the material web in a correspondingly long calendering zone in view of the speed of web travel. A web which is still wet is guided between parallel heatable surfaces which are arranged on both sides of the web and face each other through the web and can each be pressed against the web. The surfaces are designed to form and hold a given precise contour of the calendering zone over its full length. One surface is constructed e.g. as a casing of a heated roller and the second surface is constructed as an endless flexible belt which can be pressed in a direction towards the roller casing by means of a concave supporting element. If wished, the web can be calendered on both sides with the method.

Abstract: To achieve desired treatment results at both sides of a material web to be calendered, the material web is initially guided through a first nip formed between yieldable elastic surfaces confronting the throughpassing material web. In the first nip there is predominantly applied a relatively high pressure to the material web. Then the material web is guided through a successively arranged second nip formed between practically non-yieldable hard surfaces confronting the throughpassing material web. In the second nip there is applied, apart from pressure, in particular heat to the material web. The treatment result achieved in the first nip, namely the smoothness and glaze values of the treated material web, are augmented at both sides of the material web to achieve desired treatment effects.