Fountain pen communities have developed a vocabulary that can feel deliberately opaque to newcomers. This glossary defines every term you're likely to encounter, in plain English, without assuming you already know what you're looking up.
A
Air channels — Fine slits in the feed that allow air to flow into the reservoir as ink flows out. Without air channels, the vacuum created in the barrel would stop ink from flowing.
Archival ink — Ink that resists fading over time, retaining much of its original colour for decades or longer. Pigment-based and iron gall inks tend to be the most archival.
B
Baby's bottom — A nib defect where the tine tips are too rounded, preventing proper capillary contact with the paper. The result is inconsistent flow or skipping. Named for the visual resemblance.
Barrel — The main body of the pen that houses the ink reservoir (cartridge, converter, or built-in mechanism).
Bleedthrough — When ink soaks all the way through the paper, leaving marks on the other side. More severe than show-through. Typically caused by very wet ink, absorbent paper, or both.
Blind cap — The removable end cap that covers and protects a pen's filling mechanism (on piston and vacuum pens).
Blotting paper — Highly absorbent paper used to press gently onto freshly written ink, absorbing excess before it dries. Particularly useful on slow-drying papers like Tomoe River. Also called a blotter.
Blue-black ink — A traditionally popular ink colour sitting between navy and black. Originally the name described iron gall inks that begin blue and oxidise to near-black over time; now applied more loosely to any dark, blue-toned ink.
Breather hole — The small hole at the top of the nib slit (also called vent hole). It relieves pressure differences that would otherwise impede ink flow, and helps prevent flooding when the pen is inverted.
Bulletproof ink — A term from the Noodler's Ink brand for inks that bond with the cellulose in paper and resist water, bleach, UV light, and many solvents. Not literally bulletproof, but effectively permanent once dry on absorbent papers.
Burping — When a filled pen (particularly an eyedropper) releases a sudden blob of ink. Usually caused by pressure differences as the pen warms in the hand or changes altitude. Prevented by not overfilling eyedropper pens.
C
Cap — The removable piece that covers and protects the nib when the pen is not in use. Caps on most fountain pens either screw on or snap into place. Always replace the cap promptly — an uncapped nib dries out quickly.
Capillary action — The physical phenomenon that draws ink from the reservoir through the feed and down the nib slit to the paper. Fountain pens work entirely by capillary action; no pumping or squeezing is required during writing.
Cartridge — A sealed, pre-filled plastic tube of ink that clicks into the pen section. Many brands use proprietary cartridge sizes (Lamy, Pilot, Sailor, Kaweco, Platinum all have their own). Standard International is a cross-brand size accepted by many European pens.
C/C pen — Shorthand for cartridge/converter pen — a pen that accepts both cartridges and converters in the same fitting.
Clip — The metal piece on the cap used to attach the pen to a pocket or notebook cover.
Converter — A cartridge-shaped device that replaces the cartridge, allowing you to fill from a bottled ink. Operates via a piston, squeeze, or push-button mechanism. Most brands offer a compatible converter for their C/C pens.
D
Demonstrator — A pen with a transparent or semi-transparent body, making the internal mechanism and ink level visible. Originally made for salespeople to demonstrate how fountain pens work; now a popular aesthetic choice.
Dry ink / dry-running ink — An ink that flows conservatively, putting down less ink per stroke. Useful for absorbent papers (less bleedthrough) and for left-handed writers (faster drying). The trade-off is less smoothness and less dramatic shading.
Dye-based ink — The most common type of fountain pen ink. The colour comes from water-soluble dyes, making dye-based inks easy to clean, available in hundreds of colours, and generally well-behaved — but less water-resistant than pigment or iron gall inks.
E
Ebonite — Hard rubber, the material used for many vintage pens and some modern premium pens and feeds. It has a warm, slightly waxy feel and is prized for how it ages.
Eyedropper — A filling method where the entire barrel becomes the ink reservoir, filled using an eyedropper, syringe, or pipette. Gives the largest possible ink capacity, but requires a silicone grease seal on the section threads to prevent leaking.
F
Feathering — When ink spreads into the paper fibres, producing fuzzy, ragged lines instead of crisp ones. The opposite of what good fountain pen paper is designed to prevent.
Feed — The plastic or ebonite component beneath the nib that channels ink from the reservoir to the nib tip. The feed has a central ink channel and air channels; their balance determines the pen's flow characteristics.
Feedback — The tactile sensation of nib on paper. A pen with high feedback has a slight tooth or drag; a pen with low feedback glides almost silently. Neither is better — it is a matter of preference. Fine nibs on textured paper tend to have more feedback than broad nibs on smooth paper.
Flex nib — A nib with tines that spread under pressure, producing wider downstrokes and thinner upstrokes — the traditional calligraphic line variation associated with Victorian pen lettering. True flex nibs are rare in modern production pens; most "soft" nibs offer only modest line variation.
Flow — The rate at which ink moves through the pen. A wet-flowing pen puts down more ink per stroke; a dry-flowing pen puts down less. Flow is affected by the pen, the ink, and the paper.
Flooding — When too much ink reaches the nib and produces blobs or wet patches. Can be a sign of a pen that runs too wet, or caused by temperature changes expanding the air inside the barrel.
G
Ghosting — See show-through.
Gold nib — A nib made from gold alloy (usually 14 karat or 18 karat). Gold nibs are softer than steel, giving a slight springiness that some writers prefer. They are also more corrosion-resistant. Not inherently better than steel — many excellent pens have steel nibs. Typically found on pens above £100.
Grip section — The part of the pen body you hold, where the nib is mounted. Also called the section.
GSM (grams per square metre) — The standard measurement of paper weight. Standard printer paper is typically 80gsm. Tomoe River paper is 52gsm. Higher GSM generally means less show-through, though the type and treatment of fibres matters as much as weight.
H
Hard start — When a pen doesn't write immediately after a pause, requiring several strokes to restart ink flow. Usually caused by ink drying in the feed between uses.
Hooded nib — A nib where the grip section extends over and around the nib, covering most of it. Reduces evaporation and hard starts. Made famous by the Parker 51.
I
Iron gall ink — One of the oldest ink formulations, made from iron salts and tannic acids derived from plant galls. Writes with medium water resistance and darkens as it oxidises over time. Modern iron gall inks are safe for fountain pens with regular cleaning.
Italic nib — A nib with a flat, wide tip that produces distinct thick downstrokes and thin cross-strokes — the calligraphic line variation seen in formal italic handwriting. A crisp italic has sharp edges for dramatic variation; a cursive italic or stub has more rounded edges for comfortable everyday writing.
M
Maki-e — Traditional Japanese lacquer decoration technique where fine metal powders are sprinkled onto wet lacquer to create intricate designs. The most prestigious and expensive form of Japanese pen decoration; a single maki-e pen can take months to complete.
Music nib — A specialty nib with two slits and three tines, producing very high ink flow and broad lines. Originally designed for writing musical notation; now valued by calligraphers for its distinctive wet, expressive line.
N
Nib — The metal tip of a fountain pen that contacts the paper and delivers ink. Nibs come in a wide range of sizes (extra fine through double broad) and specialty grinds (italic, stub, music, fude). The quality of the nib is the single most important factor in a pen's writing experience.
Nib creep — When ink travels up the nib from the feed and covers part of the top surface. Purely cosmetic; it does not affect performance and wipes clean easily.
NID / NPD — Community shorthand: New Ink Day (when a new bottle arrives) and New Pen Day (when a new pen arrives).
P
Patina — The natural change in appearance that develops on brass, leather, and other materials with age and handling. Valued as evidence of use and character rather than as wear.
Pigment ink — Ink where colour comes from finely ground solid particles suspended in liquid. Pigment inks are typically more water-resistant than dye inks, resist fading, and can clog feeds if left to dry — requiring more frequent cleaning.
Piston filler — A filling mechanism built into the barrel itself, operated by twisting a knob at the end. Draws ink directly from a bottle. Holds considerably more ink than a cartridge or converter.
Posting — Placing the cap on the back end of the barrel while writing, to balance the pen or extend its effective length. Some pens are designed to post; others are not.
Proprietary — Components (cartridges, converters, nibs) designed to fit only one specific brand's pens. Most Japanese brands use proprietary systems.
R
Railroading — When ink flow is interrupted and the nib draws two separate parallel lines rather than one solid line. Common with flex nib pens if writing speed outpaces the ink flow.
S
Saturation — The perceived intensity or richness of an ink's colour. Highly saturated inks appear vivid and dense; less saturated inks appear lighter or more washed-out.
Shading — When ink pools differently in different parts of a letter — darker where ink accumulates and lighter where the nib moves fastest. One of the distinctive pleasures of fountain pen writing, most visible on smooth, slow-drying papers with wet-flowing nibs.
Sheen — A second colour visible in fountain pen ink when held at an angle to the light. Most visible where ink pools thickest. A blue ink might sheen red or gold; a green ink might sheen copper. Requires slow-drying paper and a wet pen to develop properly.
Shimmer — Fine metallic particles suspended in ink that create a glittery effect on the page. Shimmer inks need regular agitation before filling, should be stored horizontally, and require more frequent cleaning as particles accumulate in the feed.
Show-through — When you can see the shadow of writing from the other side of the page without ink actually penetrating. Also called ghosting. Normal even in good fountain pen papers, particularly thin ones like Tomoe River.
Silicone grease — A clear, inert lubricant used on piston mechanisms and on the threads of eyedropper pens to create a watertight seal.
Skipping — When ink flow cuts out mid-stroke and resumes sporadically. Usually caused by a dirty nib, misaligned nib and feed, or an incompatible pen-and-ink combination.
Slit — The fine cut running from the nib tip up to the breather hole, through which ink travels to the paper by capillary action. The width of the slit largely determines how wet or dry a pen writes.
Standard International cartridge — A common cartridge format used by many European pen brands, allowing cartridges from different brands to be used in compatible pens. Available in short and long versions.
Stub nib — A nib with a wider, more rounded tip than an italic, producing mild line variation between downstrokes and cross-strokes. More practical for everyday use than a crisp italic; provides character without requiring precise pen angle.
T
Tines — The two prongs of the nib that meet at the tip. The gap between them is the slit through which ink flows. Properly aligned tines are essential — one tine higher than the other causes scratchiness.
Tomoe River — A very thin (52gsm) Japanese paper renowned for its exceptional fountain pen performance: minimal feathering, minimal bleedthrough, and a surface that shows shading, sheen, and shimmer beautifully. Originally made by Tomoegawa; now produced by Sanzen as Tomoe River S. Used in Hobonichi planners and Traveler's Notebook Lightweight refills.
U
Urushi — Traditional Japanese lacquer derived from the urushi tree, applied in many thin layers and requiring months of curing. Creates an extraordinarily hard, luminous finish found on premium Japanese pens.
V
Vacuum filler — A filling mechanism that uses a plunger to compress and then rapidly release air, creating suction that draws ink into the barrel. Fills quickly and holds a large amount of ink. Used in TWSBI Vac700R and Vac Mini.
Vent hole — See breather hole.
W
Water resistance — The ability of ink to withstand moisture without smearing or becoming illegible. Most dye-based inks have low water resistance; iron gall and pigment inks tend to be more resistant.
Wet ink / wet-running ink — An ink with a generous flow, putting down more ink per stroke. Produces richer colour and more dramatic shading, but dries more slowly and may bleedthrough absorbent paper.
Wet noodle — Community term for an extremely flexible vintage nib that produces dramatic line variation with minimal pressure. Genuine wet noodles are rare and expensive; most modern "flex" nibs offer only modest variation by comparison.
If a term you've encountered isn't here, or you'd like a fuller explanation of anything in this glossary, get in touch with us at The Journal Shop — we are always happy to talk about pens.
Where to start: browse our fountain pens and fountain-pen-friendly notebooks at The Journal Shop.
