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To the Point: Ick! What Is That Stuff?

(This page published December 1, 2007)

Reference Info Index | Glossopedia  ]

This article is a slightly revised and updated version of one that first appeared in the February/March 2005 issue of Stylus Magazine. Some of the material here overlaps the content of Care and Feeding: How to Pamper Your Pens and Inks: The Good, the Bad, and the Ugly.

Cruddy nibSooner or later, every fountain pen user uncaps a favorite writer, takes a look at the nib … and grimaces.

There are several ways of discovering that all is not well with your pen’s nib. The easiest way, which usually works long before the nib gets really unsightly, is to notice that the pen isn’t writing the way it used to. It might be skipping more frequently, or it might stop entirely. So you turn the pen over and see dried stuff on the underside of the nib.

What is all of this stuff? Where does it come from? How can you get rid of it?

The most common kind of debris on nibs is simply dried ink. Just using a pen can cause a buildup of ink; if you leave your pen uncapped while you ponder your next point or while you’re listening to the boss ramble interminably, a little ink evaporates. This leaves a deposit on the nib, in the feed, or between the two. Each time it happens, more dried ink joins the party, and eventually the buildup clogs the feed channel, the slit, and the space between the nib and feed. The pen skips and finally stops altogether.

Although a dried ink clog can be easily fixed, you can prevent clogs from happening in the first place just by cleaning your pen every so often. I carry two pens, and I clean them about every two weeks by emptying them, then filling and emptying repeatedly with cold water until the water runs clear. Shaking over a sink while there’s water in a pen can dislodge stubborn ink from the back end of a self-filling pen’s sac or barrel. Use a rubber-bulb ear syringe to force water through a cartridge/converter pen in much greater volume and with more force than the converter can apply.

Before sending a clogged pen away for repair, try soaking it. Empty the pen, fill it with water, and leave it standing nib downward in a glass of cold (never hot, or even warm) water for an hour or so. Flush the pen, fill it, and test it. If it still isn’t working, start over.

For more aggressive soaking, mix one tablespoon of clear household ammonia (15 cc) with cup of cold water (160 cc). Fill the pen and soak it with only the nib and feed immersed in the solution; extended exposure to ammonia can harm some pen materials; don’t stand the pen in a full glass of the solution. Flush thoroughly before testing.

Never soak casein! Casein pens have hard rubber or acrylic gripping sections, and it is perfectly safe to soak these parts; but soaking can destroy casein barrels and caps.

“Slime In The Bottle” (SITB) is a gel-like sludge that on rare occasions forms due to unexpected chemical reactions between the substances from which ink is made. Ink makers test new inks carefully while they’re under development, and they usually find SITB before an ink hits the streets. If you see SITB (usually hanging from the nib after you fill your pen), dispose of the bottle and its entire contents. Some ink manufacturers will replace bottles containing SITB, however, so it’s worthwhile to ask before you dump anything down the oubliette. If you discover SITB as a result of pen malfunction, you’ll need to clean out the pen as described earlier. If it’s bad enough, the pen may need a trip to a repairer.

Moldy nib and feedThe most disgusting thing you’ll ever see on your nib is the white fuzzy stuff. It’s mold, real mold, just like the mold on a rotten orange except that it’s a different species. Mold is a living thing, and it reproduces by releasing microscopic spores that float everywhere. Ink contains a biocide, a substance to kill mold, but — as with SITB — things can go wrong. A batch of ink that contains too little biocide or that has been stored under improper conditions can become a growth medium for mold.

Because it is alive, mold is horribly insidious. It can spread and spread, and eradicating it can be brutally difficult. If you ever find mold floating in a bottle of ink, even if none of your pens is visibly moldy, you will need to dispose of the ink, disinfect every pen that has been filled from that bottle, and dispose of every bottle of ink from which any of those pens has been filled — and any pen you’ve filled from those bottles, and so on! The same thing applies if you find a moldy pen before you see mold in a bottle. It really is necessary to dispose of all that ink because you don’t actually know which bottle was the source of the problem.

The difficulty with mold eradication is that it requires a biocide and an ultrasonic cleaner. You can’t use only a biocide because there’s no way to ensure that it will flow into a heavily clogged area, especially in places such as the blind hole in the back of a Pelikan feed. If it doesn’t, it can leave mold behind, and a single spore is enough to reinfect things. The process also requires disassembly of the pen to disinfect every part that is exposed to ink. If you’re not an experienced repairer yourself, do not try this at home.


I’ve discussed SITB and mold here. At this writing I know of no current-production ink that is susceptible to SITB, but it is not clear that Private Reserve has solved its historical problem with occasional batches containing insufficient biocide to prevent mold. The foregoing said, if you see these problems, what is likely happening is that you’re using a bottle you’ve had for some time. Or perhaps you have just bought a bottle from a retailer who hasn’t sold enough ink to rotate out all of the stock that he or she bought months, or even years, ago. Believe me, this isn’t something you can dismiss as last year’s problem; I’ve seen moldy pens as recently as a week before this writing.

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.

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