Among traditional Japanese colors, black holds a uniquely deep meaning and history.  Around the 7th to 8th century, with the introduction of ancient Chinese philosophy and culture, the concept of Goshiki—the five colors of blue, red, yellow, white, and black—spread across Japan. These fundamental colors came to play essential roles in various fields, including politics, religion, culinary culture, and martial arts.

When thinking of black in Japan, sumi ink is the most iconic representation. While inheriting ink-making techniques introduced from the Asian continent, Japanese sumi ink evolved unique recipes and manufacturing methods adapted to local water and climate conditions. Today, advancements in modern pigments allow for creating an even wider range of blacks. Sumi ink comes in various types depending on raw materials and crafting methods, and its color nuances and application techniques vary based on the chosen media.

In this article, we explore the various types of Japanese sumi ink carefully selected by PIGMENT TOKYO, revealing their unique characteristics and the subtle colors hidden within the depths of black.

Contens

1. Understanding Sumi Ink

Sumi ink products are divided into solid ink sticks and liquid ink.

The main difference between the two is whether or not the ink is ground on an inkstone.

This is not just a preparation process, it directly affects the ink’s color and performance.

Solid and Liquid Sumi Ink: Key Differences

Ink Sticks

Made using traditional methods by mixing soot with animal glue, molding, and drying. The inkstick is ground with a little water on an inkstone to create liquid ink.

Hand-grinding sumi ink gives you total control over tone, viscosity, and bleeding effects. It has the advantage of expanding your range of artistic expression.

Liquid Ink

Already prepared as liquid ink in a bottle, it requires no grinding and is convenient to carry with you for outdoor sketching.

Although some liquid inks follow traditional recipes using soot and animal glue, most use acrylic synthetic resins as binders. Chemically speaking, these products are closer to carbon black water-based paints than sumi ink.

Note: Liquid sumi ink is not available at PIGMENT TOKYO.

Selecting Ink Based on Your Purpose

Even though they may look similar, their properties are completely different. Therefore, understanding these differences is essential for choosing the right ink for your intended use.

For instance, inksticks are best suited for artwork that emphasizes delicate tonal shifts, subtle ink washes, and controlled bleeding effects. They are also ideal for artists who value the process of grinding ink, including the quiet sound of the inkstick on the inkstone and the peaceful mindset it brings. On the other hand, liquid ink is well-suited for practice sessions where convenience is key, as well as works requiring large volumes of ink with consistent color and viscosity, such as dynamic live painting or calligraphy performances.

We encourage you to select the ideal sumi ink based on your creative style and expressive goals.

Comparing Solid and Liquid Sumi Ink

【Related article】A introductory guide to Sumi-e, Japanese ink painting

2. Crafts and Materials Behind the Black

The Ink-Making Process: Artisan Mastery in Kanzukuri

Traditional Japanese ink-making takes place during the cold months from October through April. The method is called kanzukuri, which is a Japanese term for crafting in the cold season.

Working during the winter season prevents the animal glue from spoiling, which easily happens in the high heat and humidity of summer in Japan. Furthermore, it takes advantage of collagen's natural property to solidify into a jelly at temperatures below 18°C. This ideal temperature makes the sumi ink ball easier to knead, shape, and mold. Finally, allowing the moisture to evaporate slowly and gradually in the dry, crisp winter air plays an essential role in preventing the delicate inksticks from cracking during the curing process.

Two Components for Black：Soot and Animal Glue

Soot

The colors of sumi come from soot (carbon) derived from burning raw materials. The type of sumi ink is roughly divided into Yu-en (oil soot) and Sho-en (pine soot) depending on raw materials and soot collecting methods used.

Traditionally, the "wick-burning method" was used for liquid ingredients and the "direct-fire method" for solid ingredients. Today, liquid raw materials can also be burned with direct fire, allowing for a wider variety of sumi ink to be crafted.

Oil Soot & Pine Soot: Collection Methods and Characteristics

Animal Glue(Nikawa)

This binder is an animal protein (collagen / gelatin) extracted from the hides or bones of cattle, horses, deer, and other animals.

Animal glue binds the fine soot particles together to maintain the solid shape of the ink stick, while also allowing the soot to disperse smoothly in water. When ground on an inkstone, it gives the liquid ink the ideal viscosity and smooth flow, allowing it to adhere firmly to paper or other substrates while bringing out the glossiness and delicate tonal depth unique to sumi ink.

In addition, animal glue has high water retention and moisture absorption properties. It turns to liquid when heated and sets into a solid jelly when cooled down. This temperature-driven reversibility is key to forming ink sticks.
Animal glue is not only essential to sumi-making, but is also used for many other purposes, such as a binder in Japanese painting and an adhesive for metal leaf application.

【Related Article】Solid ink sticks made without soot or animal glue

3. The Hidden Beauty of Black

Solid ink sticks are appreciated because sumi is not just simple black. By rubbing the stick on an inkstone, a wide variety of tonal shades appears. Its ingredients consist only of soot, animal glue, and a tiny hint of fragrance, but the combination of these raw materials, crafting methods, water, and inkstone creates a depth of sumi color that enriches your artwork.

Soot Particle Size and Color Tone: Oil-Soot Ink vs. Pine-Soot Ink

Soot particles originally cluster together like a bunch of grapes. When kneaded with animal glue, the glue wraps around each particle, allowing them to disperse.

While there are exceptions, oil soot and pine soot differ in particle size. Generally, oil soot consists of fine particles, while pine soot is a collection of larger particles. This difference in particle size affects which wavelengths of light are reflected, determining the color tone of the sumi ink.

As years pass, the binding strength of the glue weakens, and the dispersed soot particles begin to gather into clusters again. This process is called "aggregation," and this change in particle structure is the reason why sumi ink changes its color over time.

Note: nm [nanometer] = one-millionth of a millimeter

Oil Soot Ink (Yu-en Boku)

Particle Size: 15 – 80 nm

Color Tone: Pure black with gloss and elegance, ranging to deep brownish-grey shades when diluted.

Fired at high temperatures to form extremely fine and uniform particles, this ink reflects light directly to produce a clear black with a sheen. When grinding it on an inkstone, it has a very smooth touch, and leaves a vivid gloss on the ground surface of the ink stick itself.
Compared to pine soot, aggregation occurs much more slowly, preserving its beautiful, glossy pure black with rich depth over long periods.

Pine Soot Ink (Sho-en Boku)

Particle Size: 30 – 400 nm

Color Tone: Matte black to a mysterious bluish-grey (sei-boku).

With its low oil content and mix of various particle sizes, it creates a deep, subtle black that absorbs light through diffuse reflection. Because pine soot is not fired at high temperatures like oil soot, fine particles tend to aggregate into larger clusters over time, which is believed to make the blue tone gradually more prominent. Additionally, impurities absorbed by the pine trees accelerate glue breakdown and soot aggregation. Over time, this evolution of sumi color and the rich expression of tonal gradations becomes a major charm of pine soot ink.

Tonal Nuances in Light Ink Wash: Brown to Blue

Color Chart of Pine Soot Ink and Oil Soot Ink (Current Lineup: September 2026)

Depending on the balance of soot particles and the natural aging of the animal glue, sumi ink generally falls into two main color types, which are “brownish tones” and “bluish tones”. Due to particle characteristics, brownish tones are typically found in oil soot ink, while bluish tones are common in pine soot ink. However, crafting methods also shape the ink's unique personality, so it’s not necessarily limited to this division.

Here, we introduce popular sumi inks for each color tone.

Cha-boku：Warm Brownish Sumi Ink

Most sumi inks made from oil soot have fine particles that disperse uniformly, revealing an elegant brownish-black or pale reddish-brown shade when diluted with water. However, even with oil soot, if slightly larger particles are included, a hint of blue is added, shifting the tone toward a blue violet-black.

Sei-boku：Quiet Bluish-Grey Sumi Ink

In pine soot ink with larger particle sizes, particles aggregate over time through natural aging, creating a crystal-clear blue shade. Compared to brownish tones, dark ink produces a deep, rich black, while diluted ink highlights the stunning beauty of a translucent bluish-grey.
Some ink sticks are also intentionally crafted with pigments such as natural indigo kneaded into the ink to emphasize a delicate blue nuance.

【Related article】Explore shades of Japanese ink sticks

The Aesthetics of Aging : How Animal Glue and Water Interact

Kogaboku Seishoen

While sumi ink is often said to improve with age, not all old ink sticks turn out well, as quality changes depending on the storage environment. Differences in size and storage location create variations in how an ink stick matures. By understanding the characteristics of each aging stage, you can appreciate the shifting colors of aged ink from multiple perspectives.

Sumi ink sticks stored in a proper environment can last for 100 to 200 years. The key to this remarkable longevity lies in the balance of animal glue and moisture.

Because extra animal glue is added during the manufacturing process, fresh sumi ink is slightly sticky. While being stored, the ink stick repeatedly absorbs and releases moisture according to the surrounding climate. Over time, hydrolysis* gradually reduces the viscosity of the glue, creating the well balance between pigment dispersion and binding power.

Within three to five years, the viscosity drops significantly, making the ink much easier to use. As more time passes, it produces a clear, translucent bleed while leaving a sharp core in the brushstroke. It also allows for smooth brushstrokes, even with highly concentrated ink. As the viscosity of the animal glue decreases, the ink stick becomes lighter over time. This process is known as "aging" (or kareru in Japanese).

Moreover, in high humidity environments, bacteria can cause the ink to deteriorate within just a few days. After grinding, we recommend carefully wiping off any remaining moisture from the ink stick and storing it in a low humidity room.

*Hydrolysis: A chemical reaction in which a compound reacts with water molecules (H2O) to break down into smaller molecules. Moisture slowly breaks down the proteins in the animal glue, reducing them to smaller molecular structures.

【Related article】

4. Grinding Sumi Ink

Although the characteristics of sumi ink itself are very important, ink has a deep connection with inkstones. It is often said that ink colors appear differently depending on the inkstone used. Therefore, you can also select an inkstone according to your style of expression to further expand your creativity.

Ground Sumi Ink: Depth Created by Soot Particles

Liquid ink created by adding water while grinding solid sumi ink is called suru-sumi-eki or ma-boku-eki in Japanese. Its characteristics depend on both the raw materials of the sumi ink and the material of the inkstone itself.

A defining feature of hand-ground ink is its wide range of soot particle sizes. This occurs because the surface of an inkstone features a fine,  microscopic sandpaper like texture called houbou. Because these tiny ridges do not grind the soot particles uniformly, the resulting ink contains particles of varying sizes.

This uneven particle composition is the reason light scatters randomly. Rather than producing a flat, simple black, it brings depth and subtle nuance to the sumi color.

Color Expression and Tone Created by Particle Size

When grinding ink sticks, clusters of soot particles are formed, and their varying sizes create distinct differences in color and brush marks.

When particle sizes are varied, concentrated ink has heavy, powerful depth, while diluted ink reveals subtle shadows. This variation also enriches techniques such as bleeds (nijimi), dry brushwork (kasure), and soft shading (bokashi). These unique characteristics become more visible when the ink is diluted with water.

Soot Particle Size: Features and Comparison

Water Quality and Sumi Color: The Impact of Mineral Hardness

The hardness of the water used for grinding sumi ink directly influences both its color and how the brush moves across the paper.

In general, grinding sumi ink with soft water creates soft, delicate tones when diluted, allowing for smooth and fluid brushstrokes. On the other hand, hard water enhances the depth and richness of concentrated ink tones. Even when using the exact same ink stick and inkstone, you can feel a noticeable difference in softness on the surface during grinding depending on the water used.

If you are curious to explore this further, we encourage you to try grinding ink with different types of water and compare the results for yourself.

[Art materials used]
Sumi Ink: Daiwagaboku Watouseimyo
Sbstrated: Bamboo Washi for Ink Watercolor

Ink Grinding: Steps from Preparation to Ink Adjustment

If this is your first time grinding sumi ink, please refer to the video, the steps below, and related articles.

preparation

・Using a New or Long-Unused Inkstone

Soaking the inkstone in water before use helps the ink adjust to the surface, resulting in smoother and more effortless grinding.

・Grinding with Cold Water or in Low Temperatures

Consider gently warming the inkstone with a heating pad. Elevating the temperature reduces grinding time and helps liquefy the animal glue for better soot dispersion, producing a richer, clearer ink color.

How to Grind Sumi Ink

1.  Place Water on the Inkstone

Put a small amount of water onto the oka (the flat surface of the inkstone). Using a water dropper (suiteki) or a small water spoon helps you control the amount precisely.

2. Grind the Ink Stick

Relax your shoulders and slowly grind the ink stick against the stone surface. Move the stick in gentle circular or back-and-forth motions until the liquid thickens slightly as the ink dissolves into the water.

3. Add Water Gradually（Increase the Amount of Ink）

Repeat steps 1 and 2 until achieving the amount of liquid ink you use.

Adjusting Ink Tone (Cho-boku)

You can dip your brush directly into the ink on the inkstone. 

However, transferring the ink to a separate place is recommended if you need a larger volume, using a brush larger than the inkstone, or plan to dilute the ink to create tonal gradations.

Choose any container that best fits your brush size and the amount of liquid ink required. For making several different tones of ink with smaller quantities, a traditional Plum Motif Palette in the above photo is very convenient.

Preservation and Overnight Ink (Shuku-boku)

The shelf life and preservation of ground sumi ink are defined by the natural properties of its binder, animal glue.

When exposed to water, the protein in animal glue begins to break down over time through hydrolysis, causing decomposition. As the glue loses its strength, the soot particles in the liquid ink bind together to form clusters and settle at the bottom. This state is called shukuboku (overnight or rested ink).

This degradation happens much faster in warmer temperatures, as heat quickly weakens the adhesive strength of the glue and causes rapid particle aggregation. While shukuboku brings a unique, expressive nuance to bleeds and dry brushwork , applying it in high concentrations prevents the ink from fully penetrating paper fibers. This leads to poor results during the traditional mounting process (hyogu) for hanging scrolls or framing. For long-term preservation of your artwork, it is ideal to use up freshly ground ink on the same day.

【Related article】

Learn how to hold and grind ink sticks

About the technique of adjusting tones of sumi ink

5. Choosing and Caring for Your Inkstone

How to Choose Inkstone： Material and Size

Materials

Inkstones made of natural stone are ideal. Surfaces of a natural stone have a fine, sanding texture known as houbou to grind the solid ink stick. Stone's natural texture and density of houbou directly influence the resulting color and nuance of the ink.

Among natural stone options, Duan (Tankei) and She (Kyuju) inkstones are two of the most distinguished types. Depending on the specific quarry from which the stone was mined, each inkstone possesses unique colors, patterns, and physical characteristics, making every piece one of a kind.

Sumi ink sticks aged for 10 years or more after production become harder over time, so PIGMENT TOKYO recommends Chinese inkstones (Token), which are generally harder than traditional Japanese inkstones. 

Moreover, ceramic inkstones are softer than natural stone, and are not suited for grinding sumi ink sticks. It is used for grinding colored ink sticks.

List of Inkstones for Sumi Ink Sticks

Size

You can choose the size of the inkstone depending on your artwork size and the volume of ink required. 

A larger inkstone allows you to grind ink efficiently for big pieces, while a small size (5 inches or smaller) is ideal for smaller works and portability.

Caring Your Tools：Cleaning and Storing

Ink Stick

After use, wipe the ground surface dry with a clean paper towel, and allow the stick to dry before returning it to its box. Store the box away from direct sunlight, high humidity, and sudden changes in temperature or moisture.

Inkstone

Rinse off the ink on inkstone with plain or warm water to ensure no ink remains. If leftover ink dries and hardens on the surface, it will mix into your ink next time. Keeping your inkstone clean ensures smooth grinding and produces liquid ink with a rich, beautiful tone. Once completely dry, store the inkstone in its protective case.

【Related article】Introduction to inkstones

6. Workshop

At PIGMENT TOKYO, we host a wide variety of workshops where participants can explore painting techniques, art materials, and creative expression through both theory and hands-on practice. Our workshops are planned for everyone from beginners to active professional artists.

PIGMENT TOKYO’s Workshops (Regular & Special Events)

Workshop - PIGMENT TOKYO

Enjoying Sumi Ink: An Introduction to Hands-On Workshops

This introductory workshop allows you to learn two traditional Japanese art techniques, which are Suminagashi (Japanese marbling) and Sunago (powdered metal leaf application) techniques.

By grinding sumi ink slowly on an inkstone and facing the art materials with all senses, you will practically deepen your understanding of the properties and handling of ink. In this workshop, you can also experience the comparison of grinding ink with different water hardness levels, as introduced in this article.

We will share the key tips on how to grind ink clearly, even for those who have never touched sumi ink before. It is recommended not only for those who want to learn from the basics, but also for those who want to expand their range of expression.

【Related article】

Sitting in front of your inkstone and grinding an ink stick in a quiet environment brings a rich moment of focus that offers new inspiration for your work. We hope you will enjoy exploring this traditional color of black with your own hands.

Reference

Boku-Undo Co., Ltd.   https://boku-undo.co.jp/

・How to Sumi Ink is Made  https://boku-undo.co.jp/pages/110/

・Research and Development / Manufacturing   https://boku-undo.co.jp/pages/123/

・Sumi Ink and Calligraphy Supplies Q&A   https://boku-undo.co.jp/pages/122/

Kobaien Co., Ltd.  https://kobaien.jp/index.html

・The Birth of Sumi Ink   https://kobaien.jp/sumitanjyo.html

Kuretake Co., Ltd.   https://www.kuretake.co.jp/

・About Sumi Ink  https://www.kuretake.co.jp/product/calligraphy/sumi

Editor & Writer

Natsuko Shiraishi

Graduated from the Textile Design at Tama Art University. She is an artist who mainly works with original Washi paper and calligraphy.

Favorite matière: Paper, dynamic moves of wood fiber

Graduated from the Textile Design at Tama Art University. She is an artist who mainly works with original Washi paper and calligraphy.

Favorite matière: Paper, dynamic moves of wood fiber

Translator

Atsumi Okano

Completed her post-baccalaureate program at the School of the Art Institute of Chicago in Painting and Drawing.
While working with PIGMENT ARTICLES mainly as a translator, she also creates paintings and installations with translucent materials as an artist.

Favorite matière: Interaction of intentionality and coincidence created by the layers of transparent materials and colors.

Completed her post-baccalaureate program at the School of the Art Institute of Chicago in Painting and Drawing.
While working with PIGMENT ARTICLES mainly as a translator, she also creates paintings and installations with translucent materials as an artist.

Favorite matière: Interaction of intentionality and coincidence created by the layers of transparent materials and colors.