What Is Inkjet Pigment Dispersion?

A colourant concentrate is one part of the ink

In a pigment dispersion, the colour-bearing material remains a solid phase. In a dye solution, the dissolved colourant is present at the molecular or ionic level. A pigment dispersion can look uniform to the eye while still containing a distribution of particle sizes.

The carrier may be aqueous, solvent-based or suited to a radiation-curable formulation. This guide focuses on aqueous inkjet pigment dispersions, the field in which AIC supplies self-dispersed colourants. A dispersion designed for water-based inks should not be assumed compatible with a solvent or UV-curable vehicle.

Descriptions such as color paste, pigment preparation and inkjet colorant can refer to this intermediate liquid. “Ready to use” needs a stated purpose: ready for incorporation into a formulation does not necessarily mean ready to pour into a printer. Fujifilm likewise presents aqueous pigment dispersions as ingredients for ink formulation. [3]

Making a dispersion means separating particles and keeping them apart

The conventional process combines wetting, mechanical deagglomeration and stabilisation. Wetting brings the liquid into contact with pigment surfaces. Mechanical energy breaks down agglomerates; the stabilising system helps prevent the separated particles from flocculating again. These functions are distinct: adding a dispersant alone does not perform the mechanical separation. BYK describes this sequence in its dispersion-process guide. [1]

Manufacturing also needs control over oversized material, contamination and batch consistency. The exact operations depend on the pigment and technology. A buyer should ask what particle processing, purification and quality checks the manufacturer uses rather than infer the whole process from the word “nano” or “self-dispersed”.

How are the pigment particles stabilised?

Dispersant-stabilised dispersions

Wetting and dispersing additives interact with pigment surfaces and the liquid medium. Depending on the chemistry, stabilisation may involve electrostatic repulsion, steric protection or both. Compatibility needs to be checked after the concentrate meets the intended resin, co-solvents and other ingredients. [1]

Surface-modified, self-dispersed pigments

One route attaches hydrophilic functional groups directly to the pigment surface, allowing the modified particles to stabilise in water without relying on a conventional external dispersant. Cabot's surface-modified platform is an established example of this approach. [2] AIC's Carboxylic and Phosphate Series are aqueous self-dispersed colourant platforms.

Self-dispersion describes the stabilisation approach. It does not by itself establish that every commercial product contains no other ingredients, undergoes no particle processing or will tolerate every ink recipe. Surface chemistry and the formulation environment still have to work together. Read our surface-modified pigment formulation guide for more detail.

Polymer-encapsulated or cross-linked dispersions

Other technologies engineer a polymer structure around the particles. For example, Fujifilm describes its RxD process as a cross-linked polymer cage. [3] These architectures deserve evaluation on their own merits; there is no useful universal ranking based on the technology name alone. See our surface-modified versus polymer-encapsulated comparison for the textile formulation trade-offs.

Pigment loading and total solids are different numbers

Pigment loading states how much pigment the dispersion contains, commonly as a mass percentage. Total nonvolatile content measures what remains under the stated drying method. Where nonvolatile polymer or other material is present, that residue need not consist entirely of pigment. Confirm the supplier's definition before comparing two “solids” values.

A mass balance is useful when planning a trial. If a dispersion contains 15 wt% pigment, incorporating 20 wt% of that dispersion into an ink contributes 3 wt% pigment to the total recipe: 0.15 × 0.20 = 0.03. This assumes the stated loading is on a mass basis and no other pigment source is present. It is an arithmetic example, not a recommended ink formulation.

A more concentrated colourant can leave greater room for the remaining ingredients. Whether that helps depends on its viscosity, handling and compatibility at the required use level. Compare cost and formulation space at equal pigment content, then check colour development in the actual print.

What makes a dispersion suitable for inkjet?

Particle distribution, including the coarse tail

D50 is a median on the reported distribution basis, not a maximum particle size. D90 and, where measured reliably, higher percentiles add information about the upper part of that distribution. Number-, volume- and intensity-weighted results are different descriptions; the instrument, analysis method and sample preparation belong with the values. Malvern Panalytical explains these distinctions. [4]

A low D50 alone does not demonstrate low oversized-particle contamination or reliable filtration. D99 cannot be reconstructed from D50 and D90 alone. Use the complete report and suitable coarse-particle checks alongside storage and filtration results. Our particle-size guide covers the interpretation in more detail.

Fluid properties under stated conditions

Viscosity, pH, conductivity and surface tension help characterise a concentrate and track changes during formulation. Record the measurement conditions: temperature and shear conditions for viscosity, calibration and temperature basis for conductivity and pH, and static or dynamic method for surface tension. Dynamic measurements also need their surface-age context. KRÜSS discusses why interfacial behaviour matters during drop formation and substrate wetting. [6] Our dispersion-property evaluation guide explains the individual measurements.

Printhead requirements apply to the finished fluid. For example, Ricoh publishes 10–12 mPa·s viscosity and 28–35 mN/m surface tension for its MH5420/5440 family. Those values are a model-specific reference, not universal inkjet limits or specifications for an AIC concentrate. Confirm the operating and measurement conditions for the selected head and ink system. [5]

Stability in the concentrate and in the ink

A practical evaluation compares fresh material with stored samples, noting particle distribution, viscosity, settling and redispersibility. Repeat relevant checks after adding the proposed vehicle and binder. Define accelerated-aging conditions and acceptance criteria; a short hot-storage test alone does not establish a commercial shelf life.

For filtration, record the membrane material, pore rating, sample mass, pressure and test time. A filter result obtained under one protocol should not be treated as interchangeable with another. Continue with drop observation, idle/restart and sustained-printing trials on the intended system.

The application determines the final qualification

For textile pigment inks, dispersion stability and pigment fixation are separate tasks. Binder chemistry, fabric treatment and curing affect how well the print withstands washing and rubbing. Laundering resistance should be tested under an agreed method, such as the relevant procedure in ISO 105-C06, on the finished fabric. [8]

For paper, labels and packaging, the evaluation shifts towards colour development, spreading, absorption, drying, adhesion and the required resistance properties. Fujifilm's ink-technology explanation emphasises that pigment selection and the overall ink system both contribute to print properties, including lightfastness. [7] A dispersion's particle-size chart cannot establish those properties by itself.

These are application-development questions, not a claim that one grade is qualified for every substrate or printhead. Start with the Product Finder, then discuss the specific process and target performance.

Reading a real example: AIC-Magenta Red 1015

AIC-Magenta Red 1015 is a carboxylic, self-dispersed aqueous PR122 colourant with nominal 15% pigment content. Its supplied example report lists D50 132 nm, D90 181 nm and D97 214 nm. These are reported sample values, not interchangeable with every batch's acceptance limits.

The report does not provide D99. Nor should its distribution basis or measurement principle be assigned from the instrument supplier's name alone. Read the original particle-size report together with the model TDS and representative batch COA. Use the current specification and an agreed measurement method when qualifying a supply.

What should an ink maker ask before ordering a sample?

A useful enquiry gives the colourant supplier enough information to narrow the starting grades:

1. Define the printing system. State the application, printhead, aqueous vehicle, substrate and drying or curing process.
2. Identify the colour requirement. Give the Colour Index pigment, target shade and intended pigment loading, where known.
3. Request comparable documents. Ask for a current TDS and SDS, representative COA, particle-size report and the definitions behind solids and test values.
4. Agree a trial plan. Check vehicle and binder compatibility, filtration, storage and jetting before evaluating the printed article.
5. Set acceptance criteria. Link each decision to a method, condition and end-use requirement rather than one attractive number.

AIC supplies AIC Series Self-Dispersed Pigment Colorants for aqueous ink development. Explore the Carboxylic and Phosphate product platforms and the technical resources to prepare a grade-specific discussion.

References and further reading

Sources checked on 28 October 2026. External manufacturer examples explain particular technologies or equipment; they do not establish equivalent AIC product performance. The sample figures above come from the AIC documents linked in the example.

1. BYK: The dispersion process — wetting, mechanical separation and stabilisation.
2. Cabot: Surface Modified Dispersions — functional groups attached to pigment surfaces for aqueous dispersion.
3. Fujifilm Ink Solutions: RxD aqueous inkjet pigment dispersions — colourants for ink formulation and cross-linked polymer stabilisation.
4. Malvern Panalytical: Definition and Measurement Methods of Particle Size Distribution — distribution weighting, methods and percentiles.
5. Ricoh: RICOH MH5420/5440 — published printhead specifications.
6. KRÜSS: Inkjet printing — surface tension, wetting and drop formation.
7. Fujifilm: Inkjet Technology — Inks — formulation and finished-print properties.
8. ISO 105-C06:2010 — colour fastness to domestic and commercial laundering.