Abstract: A writing instrument cap having a tubular lower section suitable to embrace a cylindrical body of a writing instrument. An upper section of the cap is formed by a central tubular core and is closed on its top. The upper section receives a writing point of the writing instrument to make an airtight seal. The outer surface of the central tubular core has a plurality of outwardly projecting radial fins whose outer edges define a prolongation of an outer wall of the lower tubular section. The circumference of those fins accounts for less than one-half of the circumference of this prolongation of the outer wall. A plurality of clearances permit the rectilinear flow of air through the cap. Channels are formed between adjoining radial fins, and the cross-sectional area of the clearances is in excess of one-half of the total cross-sectional area between the outer surface of the central tubular core and the prolongation of the outer wall.

Abstract: A cap for writing implements comprises a hollow lower body jointed at one end to a hollow upper body, ending on top with a closed end having a smaller section; openings for the communication of the lower inner hollow body with the outside are obtained in correspondence with the jointed length; said openings alternate to sides extending from said jointed length, which are substantially parallel to the hollow upper body to form ducts stretching out towards said closed end where further communication openings are realized between the inner lower hollow body and the outside.