Editing Fountain pen (section)

===Piston filling innovation===
In 1908 Walter A. Sheaffer received a patent for an improved lever-filling pen. Introduced in 1912, Sheaffer's pens sold in rapidly increasing numbers and by 1920 Sheaffer had become one of the largest fountain pen makers in the United States.

Parker introduced the button filler, which had a button hidden beneath a blind cap on the end of the barrel; when pressed, it acted on a pressure bar inside to depress the ink sac.<ref name="Binder Lever"/>

One of the most complex filling mechanisms was introduced in 1952 with the Sheaffer Snorkel. The Snorkel had an axial tube below the nib that could be extended, allowing the pen to be filled from a bottle without needing to immerse the nib or to wipe it off after filling.<ref name="snorkel">{{cite web|title=Sheaffer Snorkel 1952–1959|url=http://www.penhero.com/PenGallery/Sheaffer/SheafferSnorkel.htm|website=Pen Hero|access-date=26 July 2016|archive-date=9 August 2016|archive-url=https://web.archive.org/web/20160809215347/http://www.penhero.com/PenGallery/Sheaffer/SheafferSnorkel.htm|url-status=live}}</ref> With the advent of the modern plastic ink cartridge in the early 1950s most of these filling systems were phased out.

Screw-mechanism piston-fillers were made as early as the 1820s, but the mechanism's modern popularity begins with the original [[Pelikan]] of 1929, based upon a patent that was initially licensed to a Croatian company Moster-Penkala by inventor Theodore Kovacs.<ref>{{cite web |title=The Patent That Launched A Fountain Pen Empire |url=https://thepelikansperch.com/2020/10/02/pelikan-piston-patent-de457462/ |website=thepelikanperch |date=2 October 2020 |access-date=9 September 2023}}</ref> The basic idea is simple and intuitive: turn a knob at the end of the pen and a screw mechanism draws a piston up the barrel, sucking in ink. Pens with this mechanism remain very popular today. Some of the earlier models had to dedicate as much as half of the pen length to the mechanism.<ref>{{cite web|title=1929–1950 – The piston filling mechanism|url=http://www.pelikan.com/pulse/Pulsar/en_US.CMS.displayCMS.93699./the-piston-filling-mechanism|website=Pelikan|access-date=27 July 2016|archive-date=28 August 2016|archive-url=https://web.archive.org/web/20160828191709/http://www.pelikan.com/pulse/Pulsar/en_US.CMS.displayCMS.93699./the-piston-filling-mechanism|url-status=live}}</ref>
The advent of telescoping pistons has improved this; the Touchdown Filler was introduced by [[Sheaffer]] in 1949. It was advertised as an "Exclusive Pneumatic Down-stroke Filler."<ref>{{cite web|title=PenHero.com – PenGallery – Sheaffer Touchdown Filling System|url=http://www.penhero.com/PenGallery/Sheaffer/SheafferTouchdownGuide.htm|website=Pen Hero|access-date=26 July 2016|archive-date=13 August 2016|archive-url=https://web.archive.org/web/20160813193804/http://www.penhero.com/PenGallery/Sheaffer/SheafferTouchdownGuide.htm|url-status=live}}</ref>

To fill it, a knob at the end of the barrel is unscrewed and the attached plunger is drawn out to its full length. The nib is immersed in ink, the plunger is pushed in, compressing and then releasing the ink sac by means of air pressure. The nib is kept in the ink for approximately 10 seconds to allow the reservoir to fill. This mechanism is very closely modeled after a similar pneumatic filler introduced by Chilton over a decade earlier.<ref>{{cite web|last1=Binder|first1=Richard|title=How to Restore the Touchdown Filling System|url=http://www.richardspens.com/?page=ref/repair/touchdown.htm|website=Richard Binder's Pens|access-date=26 July 2016|archive-date=7 October 2016|archive-url=https://web.archive.org/web/20161007001530/http://www.richardspens.com/?page=ref/repair/touchdown.htm|url-status=live}}</ref>