Lewis Waterman patented the first practical fountain pen in 1884. Writing instruments designed to carry their own supply of ink had existed in principle for over one hundred years before Waterman's patent. For example, the oldest known fountain pen that has survived today was designed by a Frenchmen named M. Bion and dated 1702. Peregrin Williamson, a Baltimore shoemaker, received the first American patent for a pen in 1809. John Scheffer received a British patent in 1819 for his half quill, half metal pen that he attempted to mass manufacture. John Jacob Parker patented the first self-filling fountain pen in 1831. However, early fountain pen models were plagued by ink spills and other failures that left them impractical and hard to sell.

The fountain pen's design came after a thousand years of using quill-pens. Early inventors observed the apparent natural ink reserve found in the hollow channel of a bird's feather and tried to produce a similar effect, with a man-made pen that would hold more ink and not require constant dipping into the ink well. However, a feather is not a pen, only a natural object modified to suit man's needs. Filling a long thin reservoir made of hard rubber with ink and sticking a metal 'nib' at the bottom was not enough to produce a smooth writing instrument. Lewis Waterman, an insurance salesman, was inspired to improve the early fountain pen designs after destroying a valuable sales contract with leaky-pen ink. Lewis Waterman's idea was to add an air hole in the nib and three grooves inside the feed mechanism.

A mechanism is composed of three main parts. The nib, which has the contact with the paper. The feed or black part under the nib controls the ink flow from the reservoir to the nib. The round barrel that holds the nib and feed on the writing end protects the ink reservoir internally (this is the part that you grip while writing).

All fountain pens contain an internal reservoir for ink. The different ways that reservoirs filled proved to be one of the most competitive areas in the pen industry. The earliest 19th century pens used an eyedropper; by 1915, most pens had switched to having a self-filling soft and flexible rubber sac as an ink reservoir. To refill these pens, the reservoirs were squeezed flat by an internal plate, then the pen's nib was inserted into a bottle of ink and the pressure on the internal plate was released so that the ink sac would fill up drawing in a fresh supply of ink.

Several different patents issued for the self-filling fountain pen design:

* The Button Filler: Patented in 1905 and first offered by the Parker Pen Co. in 1913 as an alternative to the eyedropper method. An external button connected to the internal pressure plate that flattened the ink sac when pressed.
* Lever Filler: Walter Sheaffer patented the lever filler in 1908. The W.A. Sheaffer Pen Company of Fort Madison, Iowa introduced it in 1912. An external lever depressed the flexible ink sac. The lever fitted flush with the barrel of the pen when it was not in use. The lever filler became the winning design for the next forty years, the button filler coming in second.
* Click Filler: First called the crescent filler, Roy Conklin of Toledo commercially produced the first one. A later design by Parker Pen Co. used the name click filler. When two protruding tabs on the outside of the pen pressed, the ink sac deflated. The tabs would make a clicking sound when the sac was full.
* Matchstick Filler: Introduced around 1910 by the Weidlich Company. A small rod mounted on the pen or a common matchstick depressed the internal pressure plate through a hole in the side of the barrel.
* Coin Filler: Developed by Lewis Waterman in an attempt to compete with the winning lever filler patent belonging to Sheaffer. A slot in the barrel of the pen enabled a coin to deflate the internal pressure plate, a similar idea to the matchstick filler.

The ink cartridge introduced around 1950 was a disposable, pre-filled plastic or glass cartridges designed for clean and easy insertion. They were an immediate success. The introduction of the ballpoints, however, overshadowed the invention of the cartridge and dried up business for the fountain pens industry. Fountain pens sell today as a classic writing instrument and the original pens have become very hot collectibles.

There are nine standard nib-sizes, with three different nib-tip cuts: straight, oblique and italic. The early inks caused steel nibs to quickly corrode and gold nibs held up to the corrosion. Iridium used on the very tip of the nib replaced gold because gold was too soft. Most owners had their initials engraved on the clip. It took about four months to break in a new writing instrument since the nib was designed to flex as pressure was put on it (allowing the writer to vary the width of the writing lines) each nib wore down accommodating to each owner's own writing style. People did not tend to loan their fountain pens to anyone for that reason.

Fountain pens