Lewis Waterman was a 45-year-old New York insurance broker who, in 1882, lost an important contract due to a faulty fountain pen. Vowing to develop a dependable fountain pen, Waterman researched the air-ink flow of fountain pens and created a structure based on the principle of capillary attraction, a method soon adopted by other pen manufacturers. Vintage fountain pens can suffer from a range of problems, but the most common is poor ink flow. This can be caused by a problem with the "nib," or writing implement, or with the ink reservoir or "sac."
Remove the nib from the pen casing and cartridge assembly if you're having ink-flow problems or leaking issues. Pull the cap from the top of the pen and unscrew the nib from the barrel. Unscrew the distinctive ring that separates the writing tip and the base of the pen. This decorative ring usually features the Watermen logo.
Remove the clear plastic ink converter or chamber from the nib.
Remove the long, thin ink cartridge from the barrel.
Fill a glass with a small amount of dish soap (a drop or two) and water. The water should be room temperature or cool, not hot.
Place the nib in the water and allow it to soak overnight.
Flush the nib with an eyedropper or a squirt bottle. Gently wipe dry with a dry paper towel. Once clean, closely inspect the nib to make sure it's not bent or otherwise damaged, in which case you'll probably need to replace it. Depending on the age and model of the pen, you may be able to simply unscrew the nib and replace it, or you might have to remove the nib from the ink feed. This needs to be done with great care to not damage the ink feed assembly. This is especially true if the pen had previously been filled with the wrong ink, such as India ink or drawing ink, which can get very sticky and gummy.
Inspect the ink sac. The ink sac is located at the opposite end of the pen from the nib and is a rubber or plastic, flexible container. It is the reservoir where ink is stored when you dip the tip of your pen into an ink well and draw up ink.
Remove the old, damaged sac, clean the flange area where the sac resides by gently scraping with a straightened paper clip or fine sand paper, and apply a small amount of glue or rubber cement to the flange. Insert a new ink sac and reassemble the pen.
Regular maintenance of your Waterman pen can reduce clogging and poor ink flow. Occasionally flush your pen by dipping the writing implement in cold water and drawing up a small amount. Discharge the water and repeat the process a couple times. Nibs are usually iridium-coated gold and come in various sizes and shapes to accommodate different writing styles.
Vintage or antique Waterman pens should be repaired by authorised dealers. Parts are hard to come by, are fragile and the potential for damaging old pens is great. Unless you're a pen aficionado or a jeweller, for example, it would be unwise to try to repair the lever mechanism that is slid or depressed to draw ink into the ink sac. Original Waterman pens casings were made of hard rubber and need special care in repairing and even in disassembling.