A roller coater for applying paint to mainly flat panels having different lengths includes a feed roller, an application head having applying roller and a dosing roller, and a panel conveyor. The feed roller has a cover, and the application head has vertical and a horizontal covers. Rotation supports enable a coupling and decoupling of the ends of the applying roller, and translation organs provide for withdrawing the applying roller along a L-shaped path, so as to cause an initial horizontal translation with a radial distancing, and a vertical translation. The translation organs include a vertical guide and a lifting organ for the applying roller, and removable coupling terminals at the ends of the applying roller. The interaxial distance between the feed and the applying rollers is at least equal to the length of the initial translation from the rotational supports, and shorter than the minimum length of the panels.

A method for forming a packaging material. The method can comprise moving a web of material in a downstream direction. The web can comprise fibrous material. The method further can comprise applying a moisturizing liquid to the web to at least partially wet the fibrous material. The applying the moisturizing liquid to the web can comprise receiving the web in a moisturizing station comprising at least, a drive roller and a transfer roller. The receiving the web in the moisturizing station can comprise moving the web between the drive roller and the transfer roller, and the applying the moisturizing liquid to the web can comprise engaging a face of the fibrous material with the moisturizing liquid on the transfer roller. The method further can comprise forming a film on the web, which can comprise applying a film-forming liquid to the web.

An embodiment of the present invention prevents a defect from occurring in a joint portion, in a case where a film is produced by processing a film original sheet including the joint portion. A coating device carries out processing in different manners, respectively, for a joint portion of a first porous film original sheet and a second porous film original sheet and for portions other than the joint portion.

A film is uniformly coated with a coating solution. The following formula is satisfied:

0<ac/b<113

where (i) a is a diameter (mm) of a gravure roll, (ii) b is a ratio of a circumferential velocity of the gravure roll to a conveyance speed at which the film is conveyed, and (iii) c is a volume (mL/m.sup.2) of recesses of the gravure roll, which volume is measured per unit area of a circumferential surface of the gravure roll.