Filling System Histories: Traveling on Your Thumb

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PEN WORLD MagazineThis article is a slightly revised version of one that appeared as two parts in the June and August 2012 issues of PEN WORLD magazine.

In the quest for the perfect filling system, several fountain pen manufacturers of the 1900s and 1910s took a cue from Little Jack Horner and gave us something that we could stick our thumbs into. Known as a sleeve filler or thumb filler, the simple system relied on the user’s thumb as the actuating element. But the thumb filler did not spring full-grown into being, as did Athena from the forehead of Zeus. Instead, its inventors learned from a number of near misses that preceded their own attempts.

One of the best of the near misses was the Wm. Bolles Standard Self-Filling Non-Leaking Fountain Pen. Patented in 1905 (U.S. Patent No. 798,655), Bolles’s system, an improvement on a system he had patented two years earlier and produced under the aegis of his Standard Self-Filling Pen Company, used several metal pressure bars glued around the circumference of an ordinary sac — or, as the patent discloses, it could also use a special sac with pockets molded into the ends, into which the ends of pressure bars could be inserted. To fill the pen, the user slid the barrel entirely off and then simply squeezed the sac. But, as with Bolles’s earlier system (and its competitors), if you happened to lay the barrel down where it could roll away, woe betide you!

The first of the true thumb fillers (U.S. Patent No 799,897) was the brainchild of William I. Ferris, who worked for L. E. Waterman & Company. It was a real advance on designs like Bolles’s because it did not require the user to remove (and risk losing) the barrel. Instead, Ferris made an opening in the side of the barrel and covered it with a sleeve that rotated around the barrel to expose the opening, beneath which was a pressure bar, glued to the sac. The user depressed the pressure bar with a thumb to collapse the sac. The sleeve was secured in place on the barrel by a ring protruding from the barrel’s surface and fitting into a groove on the inside of the sleeve. This design appears not to have reached production, but it was there in the files of the U.S. Patent and Trademark Office for others to examine.

Patent drawing

The unofficial Inventor’s Creed is that anybody else’s invention can be improved upon. The next workable system (U.S. Patent No. (U.S. Patent No 807,500), also issued in 1905) came from the fertile mind of William W. Sanford, one of the two principals of New York City’s Sanford & Bennett Company. Sanford designed a thumb-filling pen with an outer barrel that could slide along the inner barrel. To keep the barrel from sliding all the way off, he threaded the inside of the outer barrel’s open end and the outside of the inner barrel at both ends of the opening that exposed the pressure bar. When the user unscrewed the outer barrel from its closed position and slid it along the inner barrel, it stopped against the threads at the distal end of the opening. A couple of quick turns secured it to those threads, and the pen was ready for filling.

Patent drawing

Within a year, Sanford had received a patent for a true sleeve filler like Ferris’s (U.S. Patent No. (U.S. Patent No 828,973)). In this version, he made a wide groove in the outer surface of the barrel by reducing the barrel’s diameter in the area of the opening and covered the area with a metal sleeve that was split so that it could slip onto the barrel. When the sleeve reached the area of the opening, it snapped into the groove to become semi-permanently attached. On the side of the sleeve opposite the split was an opening corresponding to the opening in the barrel. Thus, to fill the pen, the user simply rotated the sleeve until its opening was aligned with the barrel opening. The design was elegant in that the depth of the barrel groove matched the thickness of the sleeve so that there was nothing protruding from the barrel.

Patent drawing

Between Sanford’s first and second patents, however, Otto E. Weidlich, the principal of the O. E. Weidlich Pen Company, of Cincinnati, Ohio, introduced what was actually a better design than Sanford’s second version (U.S. Patent No. (U.S. Patent No 818,803)). Weidlich’s pen, like Sanford’s, used a rotating sleeve — but instead of a metal sleeve that could scratch the barrel or be spread too far and sprung during assembly, Weidlich used a hard rubber sleeve without a split. His sleeve was thicker than Sanford’s, and it did protrude from the barrel, but it was easy to install without damage because all that was required was to heat it until it became soft, at which point it could be slid onto the pen from the end of the barrel. Because it was hard rubber, the sleeve would return to its original shape when reheated after installation.

Patent drawing

All that remained to be solved for the perfection of the Sanford/Weidlich type of sleeve filler was a way for the sleeve to be installed without heating or any other potentially dangerous methods. Solutions came at nearly the same time from two inventors: Henry R. Coit and David W. Beaumel.

Henry Coit founded the Coit Ready Fill Pen Company in Chicago in 1912 to manufacture pens to his design (U.S. Patent No. 1,124,592). He threaded the exterior of the barrel at the distal end of the opening that exposed the pressure bar and threaded the inside of the sleeve to match the barrel. The sleeve could be installed and removed without tools. By making his sleeve with a hexagonally faceted exterior, he also neatly solved the problem of keeping the pen from rolling off the user’s desk.

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

David Beaumel, president of D. W. Beaumel & Company, Inc., of New York City, had been in the pen business for several decades and had a string of patents to his credit. Applying his considerable ingenuity to the problem at hand, he secured his sleeve with a small metal pin inserted through a hole in the sleeve to engage a narrow groove running around the barrel (U.S. Patent No. 1,169,603). Unlike Coit’s, once in place Beaumel’s sleeve was permanent.

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Fountain pen Magnifying glass

Waterman actually reached production before Coit or Beaumel, with a better version of William Ferris’s original design. The basic philosophy of this model (U.S. Patent No. 950,817) was the same as that of Ferris’s earlier version, but the design used a sliding sleeve that had no opening to disturb the pen’s graceful lines. But if the pen’s cap was posted, the user had to remove it from the barrel before sliding the sleeve. This limitation notwithstanding, Waterman’s sleeve filler was a pen of elegant proportions, and — being a Waterman — one that worked well.

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

By about 1910, before the advent of Coit’s and Beaumel’s designs, the handwriting was on the wall for pens with filling systems that protruded from the barrel. Although such pens lingered on for some time, better ideas were in the works.

The first of the better thumb fillers reached the patent office in 1912, and in the same year, U.S. Patent No. 1,042,695 was issued to James W. Laughlin, founder of the Laughlin Manufacturing Company of Detroit, Michigan, for his sliding-barrel thumb filler. The key difference between Laughlin’s design and William W. Sanford’s sliding-barrel pen was that Laughlin’s had no inner barrel as such. Instead, he used a metal tube on which the back half of the barrel — much like Sanford’s — slid. But instead of threading the mating parts, Laughlin made a small shoulder on the outside of the tube at its distal end and a corresponding shoulder on the inside of the barrel at its proximal end. To fill the pen, the user simply slid the barrel until it stopped with the two shoulders against each other. The barrel’s shoulder was a close fit on the tube, so that friction between the two parts kept the barrel in place when it was closed or when it was open.

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

Thumb-filler design then languished for nearly twenty years, coming back to life in 1931 with the appearance of a pen identical in principle to Laughlin’s but sufficiently different in implementation to earn U.S. Patent No. 1,804,522 for Frank T. Walsh, an employee of the LeBoeuf Fountain Pen Company, Inc., of Springfield, Massachusetts. LeBoeuf had been producing high-quality lever fillers since about 1920, but Walsh’s sliding-barrel thumb filler really set the company apart from its competition.

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

Not content to rest on its laurels, LeBoeuf continued improving things, and in 1939, Homer J. Bessette received U.S. Patent No. 2,148,853 for his design, in which the entire barrel, not just the back half of it, slid rearward for filling. The essential value added by this later design was improved aesthetics; no longer was there a not-so-decorative band halfway along the barrel. Sadly, LeBoeuf, already bankrupt and reconstituted as the LeBoeuf-Pilgrim Pen Company, did not survive much longer.

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

Not quite a decade later, the George S. Parker Pen Company stunned the world a second time. In 1941, Parker had introduced the “51”, arguably the best fountain pen ever designed; but the original “51” was lumbered with Parker’s Vacumatic filling system, which was by then already a little long in the tooth. In 1948, the “51” was reborn with a new and elegant thumb filler (U.S. Patent No. 2,612,867, issued in 1952 to Marlin S. Baker and Harlan H. Zodtner). Initially named Foto-Fill but now universally known as the Aero-metric filler, the system featured a full-length breather tube inside the sac to allow for a complete fill. Parker designed the new “51” to be flight safe (“Up in the Air,” Pen World, April 2012). Its transparent sac was enclosed within a full-length tubular metal guard that the user exposed by screwing the barrel off the pen. (Unlike the designers of earlier thumb fillers, Parker’s engineers seem not to have been concerned about the problem of parts that must be removed and set down on the desk during filling.)

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

A major difference between Parker’s Aero-metric filler and others that had gone before was the fact that Parker’s pen, with its breather tube, required multiple squeezes of the sac in order to fill to capacity. The earlier designs all required only one squeeze — but they did not fill the sac completely, and squeezing more than once would not take in additional ink.

Also in 1948, Parker released the “21” (U.S. Patent No. 2,645,205), a lower-cost thumb-filling pen that featured an ordinary nib and feed enclosed in a nonfunctional hood to mimic the streamlined shape of the “51”. The filler in the “21” was cheaper to make; its tubular guard was only half the length of the sac, and the pressure bar was a hoop extending from the end of the guard all the way over the end of the sac and back to the guard on the other side. The “21” was also flight safe, but not in the elegant manner of the Aero-metric “51”. Instead, it had a breather tube less than half the length of the ink reservoir. The shorter breather tube prevented the user from filling the sac all the way: when the pen was stored nib upward, the level of the ink in the sac did not rise above the open end of the breather tube.

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Fountain pen Magnifying glass

When Parker’s holdings in China were nationalized in 1948, the new Shanghai Hero Pen Company inherited Parker’s thumb-filler technology. Hero still produces a variety of thumb-filling models.

During the 1950s, a few other companies hopped aboard the thumb-filler bandwagon. Among them were the makers of the three pens shown below: Moore (then in its declining years after the weak reception of its Finger tip fountain pen) with the Specialist, Esterbrook with its excellent M2, and the National Pen Products Company with several models such as the Tower hooded-nib pen that it made for Sears. None of these pens was fitted with a breather tube like the “21”; they were all single-squeeze fillers.

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

With the advent of cartridge-filling pens, self-filling pens appeared to be a moribund species. But cartridges alone were not the final solution to filling a fountain pen, and in 1960, Parker introduced its model 45, a cartridge pen designed to accept a semi-permanent unit that converted the pen from cartridge to bottle filling. Parker’s converter was a screw-operated piston type. And it was patented, forcing other cartridge-pen manufacturers to take different approaches. Sheaffer and Waterman both released thumb filler–type (“squeeze”) converters, as did at least one non-U.S. company, Pilot of Japan.

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Fountain pen Magnifying glass
Fountain pen Magnifying glass

Waterman consigned its squeeze converter to the trash heap when it began producing pens that accept the now-standard International cartridge instead of its proprietary 1953-vintage C/F cartridge. Sheaffer’s 1960s-era squeeze converter began the long walk to the Old Converters’ Home in the mid-1970s, when Sheaffer adapted its pen designs to accept a modern piston converter. But that long hike isn’t over yet because Sheaffer maintained compatibility: newer pens still accept the squeeze converter as well as the piston variety, and some users actually prefer the older design.

Pilot’s squeeze converter remains in production as I write. It is especially popular with users of the Vanishing Point pen, in which it seems to provide greater ink capacity than the twist-type piston converter normally supplied with the pen.


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