Shading, Sheen, Shimmer, Chromatography, UV Reactive: A Visual Guide to Expressive Fountain Pen Inks
If you've spent any time in the fountain pen ink world, you've probably encountered terms like "sheen," "shimmer," and "shading" used to describe inks — sometimes all at once, sometimes interchangeably, and occasionally in ways that don't quite match what you see in the bottle or on the page.
These aren't marketing buzzwords. They describe real, distinct optical properties that affect how an ink looks when it dries on paper — and understanding them is the difference between choosing an ink that surprises you on the page and one that simply looks like coloured water.
This guide covers five properties: shading, chromatography (multi-shading), sheen, shimmer, and UV reactive. Each one is illustrated with an actual swatch from our studio, so you can see exactly what we're talking about.
1. Shading
What it is: Shading describes an ink's ability to show variation in colour intensity within a single stroke or swatch — transitioning from lighter tones where the ink is thin to darker, more saturated tones where it pools. The effect is caused by the uneven distribution of dye molecules as the ink dries: areas with more ink deposit more pigment, producing deeper colour.
What it looks like on paper: A well-shading ink gives your writing a watercolour-like quality. Broad strokes show distinct gradients; fine strokes concentrate the colour at the edges. The effect is most visible on high-quality, slow-absorbing papers like Tomoe River, which allow the ink time to settle and pool before drying.
What affects it: Nib size, writing pressure, paper absorbency, and ink flow all influence how much shading appears. A wet, broad nib on slow-drying paper will show the most dramatic shading; a fine, dry nib on copy paper may show almost none.
Example — Ferris Wheel Press Porcelain Past:
Porcelain Past is a muted, dusty blue-grey from Ferris Wheel Press's Édition 2 collection — and an exceptional shading ink. The centre of the swatch fades to an almost chalky silver-white, while the edges where ink has pooled deepen into a cool slate blue. The gradient is soft and continuous, with no harsh boundaries. On Tomoe River, the effect reads almost like a watercolour wash — refined, quiet, and unmistakably expressive.
Shop Ferris Wheel Press inks at Shosai.
2. Chromatography (Multi-Shading)
What it is: Chromatography — often called multi-shading in the fountain pen community — refers to an ink's ability to separate into visually distinct colours as it dries. Unlike simple shading, which shows light-to-dark variation of a single hue, chromatographic inks reveal that they are composed of multiple dye components that migrate through paper fibres at different rates. The result is a swatch that shows two, three, or even more distinct colour bands — none of which may be obvious from the bottle.
What it looks like on paper: The separation typically appears at the edges of a wet swatch, or along the tide lines where ink has flowed and dried. It can be subtle — a warm undertone appearing at the margins of an otherwise cool ink — or dramatic, with entirely different hues appearing side by side. The effect is most pronounced on absorbent papers with slow wicking, and with inks applied wet and in quantity.
Why it matters: Chromatography is one of the most surprising properties an ink can have. An ink that looks like a straightforward olive green in the bottle may reveal teal, yellow, and brown components when swatched — turning an everyday writing ink into something closer to a miniature landscape. It rewards slow, close looking.
Example — Tono & Lims Laniakea:
Laniakea — named for the vast supercluster of galaxies that contains our own Milky Way — is a masterclass in chromatographic complexity. What appears in the bottle as a muted olive-teal resolves on paper into a layered landscape of colour: warm yellow-green in the thin areas, deep teal along the tide lines, and rich dark olive where the ink has pooled thickest. The separation is slow and geological, the kind of thing you notice more the longer you look. It is an ink that rewards patience and broad nibs.
Tono & Lims is a Tokyo–Seoul collaboration, with inks produced by Lim's Lab in South Korea — a brand that has built its reputation precisely on this kind of dye complexity. Laniakea is among their most visually ambitious releases.
Shop Tono & Lims inks at Shosai.
3. Sheen
What it is: Sheen is a metallic or iridescent colour that appears on the surface of dried ink — typically at a different angle of light than the base ink colour, and often in a completely contrasting hue. It is caused by a phenomenon called thin-film interference: when a very thin layer of ink dye dries on the paper surface rather than absorbing into the fibres, it reflects certain wavelengths of light differently than the bulk of the ink below it. The result is a secondary colour — sometimes called the "sheen colour" — that appears to float on top of the base.
What it looks like on paper: Sheen is most visible in pooled areas — wherever ink has sat wet long enough to deposit a thin film on the paper surface before drying. It appears as a flash of colour that shifts and changes as you move the paper under the light. At direct viewing angle, you see the base ink colour; tilt the page, and the sheen colour appears. The most dramatic sheening inks show a sheen colour that is almost the complementary colour of the base — a deep blue-black ink with vivid gold or red sheen, for example.
What affects it: Sheen requires the right combination of ink, paper, and light. Slow-absorbing papers like Tomoe River allow the thin surface film to form; fast-absorbing papers pull the dye into the fibres before any surface layer can develop. Broad, wet nibs deposit more ink and produce more sheen than fine, dry ones.
Example — Dominant Industry Standard Series 100 Base Black:
Base Black is not a simple black ink. The base colour is a deep, saturated carbon black with a green undertone — and on Tomoe River paper, the sheen is what defines it. In the pooled areas, a vivid dark green iridescence rises to the surface, the kind of colour that shifts and deepens as you move the page under the light: not a bright emerald, but something richer and more complex — the dark, glossy green of a beetle's carapace or a raven's wing catching the sun. Tilting the page transforms the swatch entirely. What reads as a pure, austere black at direct angle becomes a landscape of shifting dark green — quietly spectacular, and among the highest-sheen black inks available. No shimmer, no shading: just depth, and that extraordinary green flash.
Dominant Industry is a South Korean ink maker that has become one of the most respected names in the boutique ink world for precisely this kind of intensity. Base Black is a cornerstone of their Standard Series.
Shop Dominant Industry inks at Shosai.
4. Shimmer
What it is: Shimmer refers to the presence of fine metallic or iridescent particles suspended in the ink — particles that remain visible on the paper surface after the ink dries, catching and reflecting light. Unlike sheen, which is a surface optical effect produced by the dye film itself, shimmer is a physical material: actual particles, typically made of mica or similar minerals coated with metallic compounds, that sit on top of the paper fibres and sparkle.
What it looks like on paper: Shimmer appears as fine glitter or metallic sparkle distributed throughout the swatch. The effect is visible at most viewing angles — you don't need to tilt the page to see it, though direct light makes it most dramatic. The particles can be fine and subtle (creating a soft, pearlescent glow) or larger and more pronounced (creating a clear glitter effect). The colour of the particles may match the base ink, or contrast with it for maximum visual impact.
Practical considerations: Shimmer inks require more maintenance than standard dye inks. The particles can settle in the bottle (shake before use) and may accumulate in pen feeds over time (flush your pen more frequently). They perform best in pens with wider feeds and broader nibs. On the right paper — smooth, fountain-pen-friendly surfaces like Tomoe River — they flow beautifully and clog rarely.
Example — Dominant Industry Pearl Series No. 022 Early Spring:
Early Spring captures the exact quality of light on a pale morning in late March — a soft, hazy pink-lavender base scattered with fine silver and rose shimmer particles that catch the light like frost or cherry blossoms. The shimmer is fine rather than chunky, distributed evenly across the swatch, and it gives the ink a luminous, almost ethereal quality that photographs beautifully. This is one of Dominant Industry's most beloved Pearl Series releases, and it is easy to see why: it manages to be both delicate and visually rich at the same time.
Shop Dominant Industry Pearl Series inks at Shosai.
5. UV Reactive
What it is: UV reactive inks — also called fluorescent or photochromic inks — contain compounds that respond to ultraviolet light. Depending on the specific formulation, the ink may appear one colour in normal daylight and shift to a dramatically different colour under UV (blacklight) exposure, or it may glow or fluoresce under UV while appearing relatively neutral in ambient light.
What it looks like: The effect varies by ink. Some UV reactive inks show a subtle shift in hue; others produce a complete colour transformation that makes the ink appear to glow. The most dramatic examples look unremarkable under daylight — a muted, earthy tone — and then ignite into vivid neon or iridescent colour under UV exposure. The effect is entirely reversible: move the ink back into daylight, and it returns to its daylight colour.
Important note on UV reactive inks and pen use: Not all UV reactive inks are formulated for fountain pen use. Some are dip pen or brush inks only, and using them in a fountain pen may cause clogging, damage to internal components, or irreversible staining. Always check the manufacturer's specifications before loading a UV reactive ink into a fountain pen.
Example — Dominant Industry Alchemist Series – Philosopher's Stone:
Philosopher's Stone is one of the most dramatic UV reactive inks available — and the name is earned. Under normal daylight, it appears as a muted, slightly murky olive-green: interesting, but not immediately extraordinary. Under UV light, the transformation is immediate and total: the ink ignites into a vivid, glowing violet-purple, as if the page itself has been alchemically transmuted. The contrast between the two states is so complete that it can be difficult to believe you are looking at the same ink.
⚠️ Dip pen only. Philosopher's Stone is formulated as a dip pen ink and is not suitable for use in fountain pens. It is designed for use with dip nibs, glass pens, or brush application. Using it in a fountain pen risks clogging and damage.
Shop Dominant Industry Alchemist Series at Shosai.
Can an ink have more than one of these properties?
Yes — and some of the most celebrated boutique inks do. Shading and sheen appear together frequently; shimmer can coexist with shading; certain Tono & Lims inks combine chromatography with sheen. When multiple properties appear in a single ink, the result is an ink that behaves differently depending on nib width, paper, light angle, and even humidity — an ink that you are still discovering weeks after you first filled your pen with it.
At Shosai, most of the inks we carry were chosen specifically because they have at least one of these expressive properties. If you're unsure where to start, we're happy to help you find an ink that matches what you're looking for — whether that's the quiet drama of a shading ink or the full spectacle of shimmer and sheen together.
Browse our full ink collection →
All swatches in this guide were made at the Shosai studio in Gatineau, Québec, using Tomoe River paper. Shosai is Ottawa–Gatineau's boutique fountain pen ink and stationery store, carrying curated inks from Dominant Industry, Ferris Wheel Press, Tono & Lims, Pilot Iroshizuku, Colorverse, TAG Stationery, and more. We ship Canada-wide, with local pickup available in Gatineau.