The button filler was introduced by Parker in 1913. The system was born from the need to find an alternative to the Sheaffer lever filler not copying the design thus avoiding all possible legal problems due to patents.
In this case, the system requires that the compression of the rubber sac is carried out through a flexible metal strip (often called "I-bar") that is curved by pressing it with a button on the bottom of the pen. The strip in the rest position is straight and resting on one side of the pen body. On the underside it is placed in contrast with the nib assembly (in some cases a special recess is created on the body itself). On the upper side it comes out, through a curved end, from a hole made on the bottom of the pen, and inserted into a metal button.
Pressing the button causes the rod to bend towards the center of the pen, causing the sac compression. Again, a pressure bar is used to make the sac more evenly compressed. The advantage of this system is that there is no need for a side slit in the pen body. The fact that the access to the button was protected by an screw-on blind cap allowed to affirm a greater security than the loss of ink in case of breakage of the bag, also the system was promoted for its ability to allow the loading of the pen with one hand.
In fact, in addition to the previous advantages, this system also has some disadvantages. First of all, the system is more cumbersome and requires a good positioning of the flexible strip, also the filling capacity is limited, not being able to have the button a large excursion, and thus obtaining a flexion, and consequent compression, limited. Finally, pressing the button requires a certain amount of effort.
Nevertheless, the system was quite successful and was reused by various European manufacturers. In particular, an interesting variant is the push-knob made by Montblanc, in which the blind cap itself serves as a button. In fact, it can be partially unscrewed until it is brought into a position where the internal button on which the metal spring is anchored is hooked, pressing the blind cap compresses the spring and loads the pen. Once filling is complete, the blind cap can be returned to the locked position to avoid accidental pressure.
Another variant is the one patented by Soennecken in 1930, which provides for an ebonite button hidden by a shell by rotating which you can reach the loading button and operate it, while rotating it in the reverse direction this is returned to the original position, blocking access to the button. Both variants make it possible to overcome another not insignificant problem of the classic version, which is the not insignificant probability of losing the blind cap.
- at least as reported on this story of the initial Parker models, the first Parker patents related to loading, nº US-1346045 and nº US-1486246, are respectively from 1919 and 1922, certainly after the introduction, since the Duofold is also from 1922 and the system also appears in this 1916 advertising, in this discussion however is reported the purchase by the Parker of the patent nº US-787152, which is from 1905.
- Patent n° US-787152, of 1905-04-11, requested on 1904-11-19, of John T. Davison, Walker Davison, The Parker Pen Company. Self-filling fountain-pen.
- Patent n° US-1346045, of 1920-07-06, requested on 1919-04-23, of William E. Moore, The Parker Pen Company. Pressure-bar mechanism.
- Patent n° US-1486246, of 1924-03-11, requested on 1922-09-01, of Oscar B. Hjorth, The Parker Pen Company. Fountain pen.
- Patent n° US-1492451, of 1924-04-29, requested on 1923-03-17, of Walter E. Guyot, The Parker Pen Company. Refill mechanism for fountain pens.
- Patent n° US-1540763, of 1925-06-09, requested on 1921-07-15, of Samuel V. Corona, Corona Pen Company. Fountain pen.
- Patent n° GB-263341, of 1926-12-30, requested on 1926-02-16, of William Livsey, Lang - Curzon - Summit. Improvements in or relating to Fountain or Reservoir Pens.
- Patent n° US-1704470, of 1929-03-05, requested on 1926-11-27, of George W. Gilman, Corona Pen Company. Fountain pen.
- Patent n° DE-508058, of 1930-09-24, requested on 1929-09-04, Montblanc. Verschluss für selbstfüllende Federhalter.
- Patent n° GB-352184, of 1931-07-09, requested on 1929-09-04, of Christian Lausen et al, Montblanc. Improvements in fountain pens.
- Patent n° US-1819383, of 1931-08-18, requested on 1928-05-18, of Kenneth S. Parker, The Parker Pen Company. Fountain pen.
- Patent n° US-1821477, of 1931-09-01, requested on 1929-02-09, of Kenneth S. Parker, The Parker Pen Company. Fountain pen.
- Patent n° US-1826246, of 1931-10-06, requested on 1929-09-04, of Max Heerklotz, Montblanc. Closure for self-filling pens.
- Patent n° FR-739163, of 1933-01-06, requested on 1932-06-27, Edacoto. Perfectionnements aux porte-plume à réservoir.
- 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.
- Patent n° GB-471612, of 1937-09-08, requested on 1936-04-08, of Edward G. Knight, De La Rue - Onoto. Improvements in or relating to self-filling fountain pens.
- Patent n° FR-831873, of 1938-09-15, requested on 1937-04-19, Météore - La Plume d'Or. Perfectionnements aux porte-plume à réservoir.
- Patent n° US-2133617, of 1938-10-18, requested on 1937-03-11, of Benjamin W. Hanle, Eagle. Fountain pen.
- Patent n° GB-532979, of 1941-02-04, requested on 1939-09-28, of Albert J. Good, Mentmore. Improvements in self-filling fountain pens.
- Patent n° CH-228675, of 1943-09-15, requested on 1941-04-23, Météore - La Plume d'Or. Porte-plume à réservoir.
- Patent n° US-2377444, of 1945-06-05, requested on 1942-05-06, of John William Para, Karl Weisser, Wearever. Fountain pen presser bar and method of producing the same.
- Patent n° FR-932296, of 1948-03-17, requested on 1945-07-06, of Eric Ernest Samuel Wade, Charlesworth Livsey, Stephens, Lang - Curzon - Summit. Mécanisme de commande de la barrette flexible de compression de la vessie à encre pour stylographes à remplissage automatique.