UnterdruckFüller

UnterdruckFüller is a German term that translates to "vacuum filler" in English. It refers to a type of fountain pen that uses a vacuum system to draw ink into its internal reservoir. This mechanism is distinct from other filling methods like piston fillers, cartridge fillers, or converter fillers.

The vacuum filling system works by creating a vacuum inside the pen's barrel. Typically, this is achieved through a plunger or piston mechanism located at the end of the pen. When the plunger is extended, it creates a vacuum. When the nib is then submerged in ink and the plunger is released or pushed back in, the pressure difference draws the ink into the barrel.

Vacuum fillers are known for their large ink capacity, often holding more ink than cartridge or converter pens. They are also generally considered reliable and straightforward to operate once the user is familiar with the mechanism. However, they can sometimes be more complex to clean than other types of fillers.

The design of vacuum fillers can vary between manufacturers, but the fundamental principle of using a vacuum to fill the pen remains the same. This filling method was popular in the mid-20th century and is still employed by some modern pen manufacturers, often in higher-end models, valued for their ink capacity and classic filling experience.