Dripping can have various causes: temperature fluctuations, a clogged feed, surfactant residues in the system after cleaning as well as low air pressure (e.g. when flying). Current writing instruments are tested in climatic chambers and under varying pressure conditions, so that modern models do not blot under normal use as a rule; with vintage writing instruments from the 1950s it occurs more often. Often the problem also lies in improper handling or wrong filling technique — instruction at the specialist retailer can help here. For frequent flying, the StarWalker is regarded as particularly insensitive.