Translations:Funzionamento di una penna stilografica/10/en
The fact that the flow of ink is linked to the effect of the surface tension is what allows a fountain pen (besides leaving stains in the pockets of the shirts) also to write upwards, at least until the ink present inside the channel of thefeeder is exhausted. It is for this reason that many feeders have further internal grooves or sort of small bags that allow to increase this reserve, that is reintegrated every time that, putting the pen in vertical position, the gravity brings back the ink of the tank in contact with the feeder. It is always for this reason that a fountain pen, kept until a moment before in the pocket with the tip upwards, is able to write immediately (if the ink has not dried out and if the tip has an adequate curvature).