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This article is a revised and expanded version of one that first appeared in the June 2014 issue of Pen World Magazine.
The button filler was — and in many collectors’ minds still is — synonymous with the Parker name. Appearing on every Parker pen from about 1916 until the advent of the Vacumatic in the 1930s and on still more Parker pens until at least the end of the 1940s, this distinguishing feature of Parker fountain pens was patented on April 11, 1905.
The catch is that it wasn’t a Parker invention.
The story starts with John T. Davison. He and partner Philip S. Walker founded the Walker & Davison Company, a maker of gold pens (nibs) that appears to have built its first fountain pen factory in Mansfield, Massachusetts, in 1910; filed for incorporation in January 1916; filed for bankruptcy protection in September 1917; and continued in operation until at least 1922.
In 1905, Davison received U.S. Patent No 787,152 for his self-filling fountain pen. The filling system was a button, but it wasn’t quite the version that pen restorers see almost daily in Duofolds, DQs, Ravens, Challengers and Victorys. Shown here are an excerpt from Davison’s patent and a Walker & Davison pen built to that patent.
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What’s not obvious from Davison’s patent drawing is that the button and the pressure bar spring (callouts 6 and 7) are soldered together and that there is nothing to hold them in the pen’s barrel except friction. As soon as the seven-year term on Davison’s patent expired, Parker started making virtually identical pens using the exact same filler design, as embodied in the cone-cap Safety-Sealed pen illustrated below. This pen, although its name includes the word “Safety,” was not a true safety pen because its cap was not threaded and could therefore slip off accidentally.
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Not until 1916 did Parker’s engineers combine the Safety-Sealed button filler with a washer clip and the screw-cap design of the eyedropper-filling Jack-Knife Safety Pen (shown below, upper, No 14) to create the direct ancestor of the magnificent Duofold. This button-filling “intermediate” pen was also called the Jack-Knife Safety Pen. It was a true safety pen, and it was offered in a variety of sizes (below, lower, No 24, the 24 indicating the pen’s size and the indicating that it was chased).
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Parker’s first attempt to solve the problem of a pressure bar that could simply fall out of the pen was patented on July 6, 1920, by William E. Moore (U.S. Patent No 1,346,045):
This design extended the end of the pressure bar’s spring that fitted into the button, folding it back on itself and folding the new end outward to form a small tab. At the top, a hollow button like that on a round-head paper fastener covered the spring to provide a comfortable surface for the user to press against. When inserting the pressure bar into the barrel, the assembler would squeeze the two sides of the spring together to allow the tab to enter, then releasing the pressure so that the tab would catch on the edge of the hole to retain the assembly in the pen. I have found no evidence to indicate that this design entered production.
On March 11, 1924, Parker received U.S. Patent No 1,486,246 for Oscar B. Hjorth’s pressure-bar design featuring separable parts, as installed in a first-year Duofold (below, upper) and shown in the 3-D cross-sectional drawing below (lower). In this design, the button has a lip at the end inside the barrel, and there are saw cuts dividing that end of the button into four parts so that it can be squeezed through the hole in the barrel. Once installed, the button can still be pulled out forcibly, but it will not fall out of its own accord. Although the patent for this system was not applied for until 1922, the mechanism itself had been in use since at least 1920.
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Once established, Parker’s design continued in production until the mid-1940s, appearing last on two models at the lower end of the striped Duofold range. Shown here is a button-filling Lady Duofold from about 1942.
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The only significant change occurred with the 1931 issuance of U.S. Patent No 1,819,383 to Kenneth S. Parker for his three-piece design:
In Kenneth Parker’s design, the end of the pressure bar spring (callout 6) nearest the nib did not seat against the back surface of the gripping section as in the earlier design. Instead, it was attached to a secondary strip (callout 9) that hung suspended from the back end of the barrel. Pens with this pressure-bar design can be identified by the small metal tab resting on the lip of the hole through which the button passes. This clever modification allowed the company to replace its threaded gripping section with a simpler (and less costly to manufacture) friction-fitted section like that used on most lever-filling pens. It is not clear whether there was any cost saving in terms of the parts themselves, but assembly was much faster and easier with the new design.
In 1946, possibly in an attempt to supersede the aging Vacumatic, Parker introduced the VS, a new model that looked like a 51 with a different clip — until the cap was removed to reveal a full-sized open nib.
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The VS was still a button-filling pen, but by ’46 Parker had made a major improvement to the button design. Gone was 1924’s floppy brass button that was just pressed in through the loose-fitting hole at the back end of the barrel. In its place was a two-piece aluminum assembly comprising a threaded collar and a button that snapped neatly and precisely into the collar. Within less than six months after introducing the VS, Parker redesigned the barrel so that it included the collar, eliminating an aluminum part and its attendant cost. Shown here are the two button versions, the earlier one to the left and the later version to the right.
On the other hand, pressure-bar design took a step backward. With the button assembly screwed into the barrel, there was no way to use Kenneth Parker’s suspended pressure bar; and the old full-length bar returned, bringing with it the threaded section design.
The last hurrah for American-made Parker button-fillers, the VS proved unpopular and lasted only two years. But Parker continued building Duofold variants in the United Kingdom into the 1950s, fitting some of them with squeeze fillers and some with VS-style buttons.
As I said at the outset, button fillers were not the exclusive property of Parker, not even after Walker & Davison closed down in the 1920s. But, as with so many inventions, competitors often found themselves in the position of having to come up with variations that were sufficiently novel to be patented. One such was Samuel V. Corona, who happened to be located in Janesville, Wisconsin, where Parker was also based. Corona took the ordinary button filler, essentially Parker’s version, and fitted it with a twist knob instead of a button, as shown by the drawing below, from U.S. Patent No 1,540,763, issued to Corona on June 9, 1925. The knob operated a cam (callout 15) that caused a second cam (callout 18) to move longitudinally in the barrel, compressing the spring element of the pressure bar lengthwise and thereby causing it to bow away from the barrel wall, pushing the pressure bar into the sac. A quarter turn of the knob in either direction served to compress the spring, which in turn moved the pressure bar to compress the sac in the usual way. With another quarter turn, the spring returned the cams to their rest positions as it straightened itself out again, allowing the pressure bar to return and the sac to ingest ink.
The photos below illustrate a typical Corona pen.
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Corona’s patented filler was publicly advertised in 1922 and was apparently used in early production, but an improved design soon appeared. The Jade celluloid pen shown above, almost certainly produced after the 1925 patent was granted, bears an imprint indicating that a patent had been applied for, and its filler mechanism is of a much simpler and less costly design. The two-piece knob has been replaced by a one-piece knob that drives a rotating cam, as before, but that cam fills the entire inner diameter of the barrel. The cam is shaped as shown by the green part in this drawing:
The spring element of the pressure bar (yellow) rides on one of the helically sloped surfaces of the cam. A disk (red) with a notch on its edge is fastened in the barrel. The spring passes through the notch, and the disk keeps the spring (and thus the pressure bar) from moving sideways. As the knob rotates the cam in the direction of the red arrow, the cam pushes the end of the spring in the direction of the blue arrow, just as a button would do. The spring bows, pushing the pressure bar into the sac. When the cam has turned half a turn, the spring falls off the end of the slope, releasing the pressure bar from the sac, and the sac draws in ink. Although applied for, the patent for this design was never granted.
During the 1930s and 1940s, Arnold, Peerless, Wearever and a few other U.S. brands also offered button-fillers along the general lines of the Davison system, including — in some cases — soldered assemblies of the button and pressure bar. Most of these companies were in the third tier; their pens were made cheaply, with friction-fitted sections that were glued into the barrel. Shown below is a Wearever Pacemaker from the 1940s; this pen has a red injection-molded plastic button, and the back end of the barrel is fused into place so that the only way to gain access to the pressure bar and the button is by removing the section. There’s an interesting piece of trivia about Wearever button-fillers: David Kahn, Inc., acquired machinery from Germany in the late 1920s to experiment with injection molding and subsequently became probably the first pen company to adopt the process. During World War II, Kahn had a government contract to produce injection-molded valve caps for jeep and truck tires. Seventy years later, Wearever blind caps will still fit the valve stems on your car’s tires.
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The button-filler concept was not the exclusive property of U.S. companies. A few European companies also chimed in with their own versions of the system, and some of those pen models were being produced in the twenty-first century. Dominator in France and Merlin in Germany both built pens with fillers mechanically identical to the post-1924 Parker system (shown below, first and second pens). Earlier in this article I mentioned Parker’s U.K. division and its VS-style filler. Filcao, an Italian company founded in 1964, introduced its first button-filler, the Columbia (below, third pen), in 2005, following that introduction over the next few years with other models, such as the Atlantica and the Silvia.
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The filler in Filcao’s pens followed the general pattern of the post-1924 Parker, but its button — instead of being pressed into the back of the barrel — was retained by a threaded metal collar. The Filcao button was secured positively by the collar; unlike the button in the Parker VS, it could not be pulled out without removing the collar from the barrel.
A fascinating button-filler variation came from Soennecken in Germany and was fitted on the company’s Rheingold product range. The Rheingold 613 pen illustrated below also appears in Filling System Histories: The Bulb. It was technically a bulb-filler with a button actuator, but Soennecken also used the button-filler portion of the design on pens with full-length sacs.
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The button in the usual button-filling pen is concealed beneath a blind cap; but Soennecken, following the inventor’s dictum that says there is always a way to improve on your competitor’s design, came up with a better system (German Patent No 625,472, issued February 6, 1934; an improved version of an earlier Soennecken patent). A collar surrounding the button could be screwed upward to shield the button from inadvertent pressure or downward to expose it for filling. While more complex to manufacture, this design eliminated the removable blind cap and the concomitant risk of losing it while filling one’s pen.
The last hurrah for button fillers outside the U.S. came after World War II in the form of a Leverless model produced by Mabie, Todd & Company, then located solely in England. The original Leverless, a prewar pen, had featured a unique filler whose design is not within the scope of this article; its postwar descendant, still called the Leverless, was an ordinary button filler except for the button — or, more accurately, the lack thereof. Instead of a button, this design (U.S. Patent No 2,579,343) featured a twist knob, thereby presenting the user with the same filling method as before. The knob drove two screws that worked like a very short-throw differential piston filler (described in Filling System Histories: Piston Pens) to press on the end of the pressure bar as a button would. Enhancing the compression was a trapezoidal piece of wire whose angled side rode in a hole at the end of the pressure bar. Before the screws pushed far enough to compress the spring, the end of the spring spring slid upward along the angled side of the wire part, beginning the process of collapsing the sac and ensuring that the sac would be completely deflated.
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And that, I think, just about buttons up button-fillers.
For the purposes of this article, the term “button filler” is limited to mean either a pen with a filling system whose actuator (usually a short-stroke button or stud at the back end of the barrel) compresses a pressure bar’s spring longitudinally, forcing the spring to bow away from the barrel wall and drive the puressure bar proper into the sac, deflating it, or the filling system itself. 
Several official Massachusetts state records list the town erroneously as Marshfield.
The information in this article is as accurate as possible, but you should not take it as absolutely authoritative or complete. If you have additions or corrections to this page, please consider sharing them with us to improve the accuracy of our information.
This article is also available as a chapter in The RichardsPens Guide to Fountain Pens, Volume 3, an ebook for your computer or mobile device.
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