The bulb filler is probably the progenitor of all filling systems based on the presence of a breather tubes. Its origins are uncertain, one of the oldest patents (nº US-802668 of 1905) was granted to the Aikin Lambert, but there is an earlier one (nº US-723726 of 1903) that does not seem to have been used. But beyond the precursors one of the first models to have been massively produced and marketed is certainly the one of the Postal of 1925, although the most sophisticated version probably remains that of the Stylomine 303. Later the same system was also adopted by Eversharp for the Bantam model and for the stenographer-centralist version by Doric, and by Pelikan for the Rappen.
The system involves the direct use of the pen barrel as a reservoir, also allowing, when this was made of transparent material, the visualization of the ink level. Filling is carried out by pressing a rubber pump, similar to that of a dropper, inserted directly on the bottom of the body of the pen, and which can be accessed by unscrewing the bottom of the pen. Given the need to have a pump of sufficient size, this generally involves on this type of pen a much longer blind cap than that used on other filling sistems, such as the button filler or the piston filler.
The filling principle derives from the dropper principle, the pen tip is immersed in the ink and the pump is pressed, its expansion causes a depression that causes the ink to flow into the body of the pen. The innovation created by this filling system consists of the presence of the breather tube connected to the nib unit and directly connected to a duct in the ventilation hole of the nib.
This allows you to repeat the pressure on the pump several times, to perform different filling actions and progressively fill the pen. In the absence of the breather tube in fact, with the compression of the pump, the ink present in the barrel would escape, since there is no vent for the air contained in the same, thus obtaining a very limited capacity; the breather tube instead provides a way out to the air present in the tank that is compressed by the pump, and a way in for the ink that is sucked in by the depression. In this way it is possible to repeat the compression of the pump and continue to load ink until the latter does not exceed the level of the breather tube, completely filling the pen.
- Patent n° US-723726, of 1903-03-24, requested on 1902-12-06, of George W. Perks, Frederick C. Thacker, Unbranded. Fountain-pen.
- Patent n° US-802668, of 1905-10-24, requested on 1904-10-22, of Huston Taylor, Aikin Lambert. Fountain-pen.
- Patent n° GB-190720065, of 1908-07-16, requested on 1907-09-09, of Alexander Munro, Unbranded. Improvements in Reservoir Pens.
- Patent n° US-1037660, of 1912-09-03, requested on 1912-01-10, of Felix Riesenberg, Unbranded. Fountain-pen.
- Patent n° GB-191218716, of 1912-09-03, requested on 1912-09-12, of Felix Riesenberg, Unbranded. Improvements in and relating to Fountain Pens.
- Patent n° FR-712327, of 1931-09-30, requested on 1930-06-12, of Yves Zuber, Stylomine. Nouveaux porte-plumes à réservoir.
- Patent n° GB-374274, of 1932-06-09, requested on 1930-06-12, of Yves Zuber, Stylomine. Improvements in or relating to reservoir pens.
- Patent n° US-1876298, of 1932-09-06, requested on 1931-01-08, of John A. Holland, John Holland Pen Company. Self-filling pen.
- Patent n° FR-737930, of 1932-12-19, requested on 1931-09-24, of Yves Zuber, Stylomine. Perfectionnement aux porte-plumes réservoir.
- Patent n° FR-750689, of 1933-08-16, requested on 1932-05-11, of Yves Zuber, Stylomine. Porte-plume à réservoir à «plume-pointe», pouvant être à débit d'encre régularisé, permettant les très grandes contenances.
- Patent n° GB-416648, of 1934-09-18, requested on 1934-05-08, of Mark Sydney Finburgh, Wyvern Fountain Pen Company. Improvements in fountain pens.