Feeds: Revolution, Evolution, and Devolution

(This page revised September 22, 2012)

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The Alimentary Tract of a Fountain Pen comprises three organs: the ink reservoir, the nib, and the feed by which these two are connected so that ink may pass from the one to the other. The release of ink by a fountain pen has been referred to as a “controlled leak,” and it is the feed that exercises that control. To do so requires a surprising degree of sophistication; not only must the feed meter the amount of ink flowing to the nib, but it must also permit just the required amount of air to flow in the opposite direction, to replace the ink as it is used.

Cutaway view of nib, feed, section, and sac

Because the problems of airflow control were not well understood, early feeds were designed only to provide a capillary surface across which ink (but not too much of it) could pass on its way to the nib slit. A very simple approach to this problem is to make a feed that is slightly smaller in diameter than the bore of the section and wedge the feed into the bore with a piece of wire so that the feed is in contact with the surface of the nib and the bore itself. Some early pens, such as Mabie Todd Swan overfeed models, used this approach. But a simple feed of this type has no way to meter air into the reservoir; as ink is used, a partial vacuum builds up in the reservoir, holding the ink in instead of allowing it to flow out. When external air pressure is sufficient to overcome the ink’s surface tension, a bubble is forced into the reservoir. (This frequently occurs when the writer disturbs the surface tension by shaking the pen.) The sudden release of the partial vacuum releases a drop of ink, which appears on the paper as a blot.

The Birth of the Modern Feed: Legend has it that in 1881, Lewis Edson Waterman, working as an insurance agent, experienced a disastrous blot that cost him the sale of a contract. His anger and frustration drove him to invent a new feed design for himself. Whittling bits of hard rubber at his kitchen table, so the story goes, Waterman discovered a way to meter the flow of air back through the feed into the ink reservoir. He did this by cutting a set of channels in the surface of a feed that was the exact diameter of the section’s bore. First, he carved a wide, shallow, flat-bottomed channel. By itself, this channel was no more than a different way of doing what the smaller-diameter feed had done, and in fact Waterman wasn’t the first to do this. But he then carved three very narrow channels (properly known as fissures) into the floor of the wide channel. Capillary action drew the ink into the fissures, allowing the air bubbles to flow over the ink through the wide channel and into the reservoir. And the modern fountain pen was born. Two years later, in 1883, Waterman applied for a patent on his invention, and U.S. Patent Nº 293,545 was granted in 1884. In his patent, he carefully did not specify the number of fissures so that others could not get around his patent just by using, for example, two fissures instead of three.

Feed cross-section Cutaway view of nib, feed, and section
Waterman’s ink fissures are visible in these drawings. Note how the
channels pass under the nib to provide a closed path for ink and air.
(Drawings not to scale)

The new feed proved so successful that Waterman began making pens for his friends, and he soon found himself making pens for sale. Waterman called his product Waterman’s Ideal Fountain Pen, and his business grew into the L. E. Waterman Pen Company, whose descendant is today’s Waterman company of Paris, France.

Other manufacturers couldn’t simply follow Waterman’s example; it was protected by patent. So, although others understood immediately what he had done, they had to take other approaches. A Mabie Todd design of the period combines an overfeed and an underfeed. In this design, there is a broad flat ink channel in the hard rubber feed along the nib’s under surface, and there is also a square hole broached longitudinally through the center of the feed, with a round plug inserted to meter air flow. The plug supports a twist of wire that extends back into the reservoir. This feed actually works moderately well, although it is not so reliable as a Waterman feed.

The Occasional Extra Drop: Even with Waterman’s revolutionary feed, fountain pens weren’t quite reliable enough for blot-free writing. Motion of the pen in use, changes in temperature due to the writer’s grasping a cold pen, and other factors could result in flow irregularities. Something was needed to buffer these irregularities. Waterman modified his original feed by carving “wells” alongside the channels. These wells, located under the nib, were within capillary range, and excess ink could flow into them and have a place to pool. The ink in the wells could flow back out when flow from the reservoir abated. Waterman patented this design in 1899, calling it the “Spoon” feed. The following figure shows a Waterman Spoon feed:

Waterman feed

Again, other manufacturers were left to find alternate ways of doing what Waterman’s design did. Various approaches appeared, such as Roy Conklin’s use of lateral cutouts in the sides of the feed, as shown here:

Conklin feed

Draining the Swamp I: George S. Parker’s response to this concern, introduced in 1894, was the famous “Lucky Curve” feed (U.S. Patents Nos 512,319 and 606,231). When a pen was capped and placed in the pocket with its nib upward, excess ink was frequently left in the feed, prevented by capillary action from flowing back into the reservoir. Later, when the pen was brought into use again, the pressure of the ink in the reservoir could drive that ink out, making a blot. Parker added a protuberance to the back of the feed. He curved this addition so that it touched the wall of the reservoir, providing a way for the excess ink to drain out of the feed. Thus was born the Lucky Curve feed. The Lucky Curve solved most, but not quite all, of the problem, and in about 1905 Parker introduced a refinement by cutting notches in the sides of the feed to create the eye-catching “Christmas Tree” feed (U.S. Patent Nº 778,997). This design remained in use until the late 1920s:

Parker Lucky Curve feed

The development of feeds during the early part of the 20th century was primarily a continuing effort to provide a more reliable buffer system. In the late 1910s, pens began to appear with comb feeds, having a series of sawn cuts, or serrations, on the sides of the feed where Conklin’s cutouts and Parker’s notches had been. In the 1930s, Sheaffer made the serrations finer, cutting them all the way around the feed to create an improved feed with a much greater buffering capacity than the earlier comb feed.

The next real advance in feed design, the addition of a breather tube, appeared on pens of several different filler designs, such as bulb fillers and accordion fillers. A properly designed breather tube improves flow control by affording a direct passage for air to reach the back end of the reservoir. The design is best illustrated by Parker’s 1932 development of the Golden Arrow, which soon became the Vacumatic. The Vacumatic feed, with serrations and a breather tube, is shown here:

Parker Vacumatic feed

Draining the Swamp II: Feeds with breather tubes have a unique problem: it is more difficult to empty a pen with such a feed because operating the filler tends to force air down the breather tube instead of forcing ink down the feed channels. This happens because the volume of ink in the barrel offers greater resistance to flow than the tiny amount in the breather tube. The solution is to operate the filler very slowly until a drop of ink emerges from the feed; in most cases, you can then complete the filler motion fairly rapidly.

Sheaffer’s solution to the problem of draining ink back into the reservoir was the center-channel feed. In the mid-1930s, Sheaffer drilled a hole longitudinally into the feed from the rear but did not drill all the way out the front, and cut a slit to give passage from the hole to the surface under the nib. They then inserted into the hole a small-diameter rod of hard rubber that was milled flat along one side. A fissure carved into the flat surface provided a path for ink to flow from the reservoir down the length of the hole in the feed, whence the slit carried it to the nib. By curving the center-channel rod until it touched the side of the reservoir, the engineers created the same kind of path that had been provided by Parker’s Lucky Curve feed, which had by then been discontinued.

Other manufacturers took other approaches. In 1941, Wahl-Eversharp began producing a feed with several broad channels running longitudinally (U.S. Patent Nº 2,255,093). These channels provided a buffer to soak up temporary excesses of ink while at the same time allowing that ink to flow toward the back end of the feed. This design, called the Magic Feed, introduced another novel feature, the use of fine serrations, or comb cuts, toward the rear of the feed; it was toward these serrations that the longitudinal channels directed the excess ink to prevent blotting. Here is a Magic Feed with its breather tube:

Eversharp Magic Feed

The Second Revolution: In 1941, Parker stunned the pen world with the introduction of a radically new pen, the “51”. Designed to use Parker’s new super fast-drying “51” ink, the pen had the ability to store a huge amount of ink in very close proximity to the nib. This secondary reservoir, so to speak, ensured that enough fluid was always available to keep the pen wet by counteracting the effects of rapid evaporation. The patented feature that made the system work was a precision-machined part called the collector (part of U.S. Patent Nº 2,223,541). In a technical sense, the collector, with its great number of very fine comb cuts that reach all the way around the exterior, was the actual feed in the “51”. Instead of resting against the under surface of the nib, the collector entirely enclosed the nib, which was made much smaller. A small hard rubber “feed” running through the center of the cylindrical nib bridged the final short distance between the collector and the nib slit. Here is a “51” collector with its feed and breather tube:

Parker "51" collector and feed

The tiny feeds in early versions of the “51” had no fissures; the collector had on its under side a slit (visible in the above illustration) that served to convey the ink forward, while on the top side there was a broad air channel. The company later added a fissure to the feed to coincide with a slight design change to the nib, providing better flow control to the nib’s tip.

Eversharp’s Magic Feed and Parker’s “51” collector both featured ink storage within the pen. Other manufacturers adopted the same feature in different ways. Sheaffer, in 1942, introduced the conical “TRIUMPH” point (U.S. Patent Nº D130,997), for which the company designed a new feed that provided ink storage within the gripping section. Otherwise, this feed was much like the earlier center-channel feed, and Sheaffer continued using the latter in its open-nibbed pen models. In 1952, however, Sheaffer announced the Snorkel pen; for this new filling system, a hole appeared all the way through the feed so that the small filling tube could extend forward past the tip of the nib. The center fissure was now contained within this Snorkel tube. The following figure illustrates the feed from a Snorkel with a “TRIUMPH” point:

Sheaffer “TRIUMPH” feed

Open-nibbed Snorkel pens, and the TIPdip pens that appeared at about the same time, used a feed much like a center-channel feed with the hole drilled all the way through. In the Snorkel models, the Snorkel tube took the place of the center channel, while the TIPdip retained a center channel that also participated in the filling process.

Although feed technology was well understood by the 1950s, not all manufacturers seemed to pay attention to what had been learned. Makers of cheap pens often produced feeds made of plastic, with molded-in designs that looked like serrations (but were not functional) or the merest token wells to reduce blotting. Here is a cheap plastic feed from a Wearever pen of the 1950s; note the lack of serrations:

Wearever plastic feed

Plastic, although it is an ideal material for economical high-speed manufacture of complex parts in large quantity, is not so felicitous as a material for feeds. It is nonporous, and because it is injection molded, it frequently has a very smooth, polished surface. Feed makers employed various ways to combat these deficiencies, such as roughening the surfaces of the molding dies. Not all of these techniques succeeded in producing reliable feeds.

The Modern Era: In the latter part of the 20th century, many new feed designs appeared to accommodate cartridge-filling pens and, later, cartridge/converter models. Many of these more recent feed designs provide a collector-like reservoir within the section as well as good comb serrations under the exposed nib. The following illustration shows the feed from a Stipula Etruria pen:

Stipula feed

Some modern feeds, especially those in pens of higher quality, are made of hard rubber, while others are made of plastic. Many plastic feeds today are coated with a substance that gives them the desired slightly rough, porous surface. In most cases, the result is a good feed; but some designers, in an apparent attempt to make their feeds aesthetically pleasing, have sacrificed function; they have produced designs that are notoriously balky and unreliable due to inadequate airflow handling. In some cases, but not in all, these feeds can be modified to work reasonably well.

Notes:
  1. Waterman’s corporate history describes the function of the feed channels incorrectly, saying that the three fissures allow air to flow under the ink in the broader channel. This description is at odds with the history’s earlier declaration that Waterman’s discovery was based on capillarity (which would, of course, pull the ink into the fissures).  Return to text

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