|Filling Instructions: Piston-Fillers|
The standard filling mechanism for better European-made self-filling pens since the later 1930s, piston-fillers utilize a screw mechanism to move a piston inside the barrel, taking in and expelling ink. The mechanism is typically actuated by turning a knob at the end of the barrel, although in some instances the turning knob is concealed underneath a blind cap. While some piston-fillers incorporate a "tip-dip" feature, in most cases the nib must be fully immersed when filling, just as with other pens.
Montblanc piston-fillers made up until the beginning 1960s used a two-stage screw mechanism. Very little resistance is felt for the first few turns, which can fool the uninitiated into concluding the pen is broken.
If a piston-filler has been put away for a long time, and especially if it has been put away with ink inside, it is possible that the piston will be stuck. Do not force a stuck piston, as it can damage the screw mechanism or tear the seal..