Abstract: A mechanical seal has a predetermined number of fine grooves formed on a sliding surface thereof, both ends of the fine grooves respectively reaching the outer peripheral end and the inner peripheral end of the sliding surface, part of the fine grooves being inclined forwardly and the remainder inclined rearwardly with respect to the relative rotational direction of the sliding surface. With those fine grooves it is intended to improve the sealing effect and the lubricating effect of the sliding surface. Also provided is a method of forming such a sliding surface.

Abstract: A mechanical seal has a predetermined number of fine grooves formed on a sliding surface thereof, both ends of the fine grooves respectively reaching the outer peripheral end and the inner peripheral end of the sliding surface, part of the fine grooves being inclined forwardly and the remainder inclined rearwardly with respect to the relative rotational direction of the sliding surface. With those fine grooves it is intended to improve the sealing effect and the lubricating effect of the sliding surface. Also provided is a method of forming such a sliding surface.

Abstract: A plate making method for gravure printing which method is easy to carry out and excellent in the tone reproducibility of highlight portion. The method of the invention comprises the steps of: A. exposing a photosensitive material to light source through a gravure screen having desired number of transparent lines; B. exposing the photosensitive material to light through a tint screen and continuous tone positive; C. further exposing the photosensitive material to light through only the continuous tone positive; and D. treating the exposed photosensitive material with succeeding plate making steps such as transferring, developing and etching, in which the order of the above exposing steps A, B and C is not fixed.

Abstract: An improved method of screen gravure photoengraving using a half-tone positive in which the gradation is fully represented by the variations of both sizes and depths of ink cells formed in the printing plate and the formation of moire pattern can be prevented without requiring strict registering in exposure steps, and the method comprises the steps of, for example, exposing a photosensitive material such as a carbon resist to a light source through a gravure screen having transparent crosslines, further exposing the photosensitive material to the light source through a half-tone positive, again exposing to the light source by interposing a diffusion sheet between the half-tone positive and the photosensitive material, then transferring thus exposed photosensitive material on a gravure cylinder and carrying out developing and etching.