Abstract: A sealing cap for a writing, drawing or painting instrument includes an axially extending tubular member open at one end to receive the instrument. An interior space extends axially within the tubular member from the open end and is closed at the opposite end. An axially extending air channel, open at both ends, is located within tubular member. One open end of the air channel opens to an at least partially laterally closed space which is open outwardly from the closed end of the interior space. The other open end of the air channel is open to the interior space. The air channel does not interfere with the sealing effect of the interior space when an instrument is inserted into the space. Accordingly, whether the cap is fitted on the instrument or is removed from it, there is a continuous open path for the flow of air through the air channel.