Ιn recent years, DTF (Direct To Film) technology has become an important part of the (digital) textile printing sector. Thanks to its ability to deliver vibrant colors, high durability, and application on a wide variety of fabrics, it is now an essential tool for professional printers as well as for small businesses.

The heart of this process is none other than DTF ink. Although most people see only the final result on a t-shirt or a bag, very few know what exactly this ink contains and how each of its components contributes to the flawless final outcome.

In this article we will explore the basic ingredients of DTF inks, what excaclty their role is for, and why their quality is considered important.

DTF inks are specially designed for use in inkjet printers, modified for Direct To Film technology. Unlike other inks, such as those of digital Sublimation printing method, DTF inks have a different chemical composition in order, in summary:

• to adhere properly to the special film
• to withstand the high temperatures of the heat press
• to maintain vivid colors after washing and/or abrasion

The basic ingredients of DTF inks

DTF inks consist of a combination of four main components: the carrier/solvent, the pigments, the dispersants, and the binders/resins. The composition of these inks is supplemented by other elements which, due to their small content, will be mentioned briefly. For now, let us look at each category of the main ingredients.

Carrier/Solvent

The main part of a DTF ink solution is the carrier/solvent, which is deionized water with a typical concentration range of 40–65%, mixed with a small percentage (5–20%) of co-solvents (e.g. glycerin, 1,2-propanediol/propylene glycol, 2-pyrrolidone, diethylene glycol). Its primary role is to maintain the viscosity and surface tension of the ink at the desired levels to achieve proper jetting(1). Secondarily, the carrier controls the evaporation–drying of the ink, in order to avoid easy/rapid drying of the printer head nozzles. Due to its composition, it is characterized as environmentally friendly.

Pigments

Pigments are microscopic particles which, as their name indicates, are mainly responsible for the color of the ink. The basic inks used in DTF digital printing technique, are the CMYK inks and white ink. The former contain organic pigments, while the latter, which is more particular, contains titanium dioxide (TiO₂) of high scattering(2). This is a white, inorganic pigment characterized by high whiteness and opacity. The presence of this substance in the composition of white ink explains why white ink appears denser and more opaque compared to the CMYK ones.

The typical pigment concentration range is 5–15% for CMYK inks, while this percentage increases significantly in white, where it ranges between 20–35% of TiO₂. The role of the pigments is on the one hand to provide the desired color to the ink (CMYK), and on the other hand to achieve the required opacity and coverage.

Indicatively, certain critical specifications concerning white ink and related to the pigment it contains are mentioned. Specifically: D50 ≈ 0.2–0.3 μm, D90 < 0.8–1.0 μm, Narrow PSD, stable pH and ionic strength.

Dispersant

The dispersant is the element that ensures the uniform distribution of particles within the aqueous solution of the ink, so as to avoid both the agglomeration of the various suspended particles and the tendency for sedimentation, two problems that can cause serious issues during printing. In other words, dispersants are the substances contained in inks that keep them “alive” and ready to use. The typical range of these substances is between 1–5% of the total, or 5–20% of the pigment content. The value determined by the manufacturer is particularly critical, as a high value leads to an increase in viscosity and thus difficulty in ink flow, while a low dispersant content may lead to foaming, poor wash fastness as well as an oily print surface that prevents powder adhesion at the subsequent stage.

Binders/Resins

Binders, or resins, constitute the connecting link of the entire DTF digital printing process. They are polyurethane dispersions (PUD), often with acrylic copolymer, and their typical concentration range is between 10–25% as solid resin. With respect to the production process, they are responsible for the smooth adhesion of the ink to the printing medium (film) and later for the adhesion of the print to the fabric after transfer, providing flexibility and resistance to washing/abrasion in the final result.

Complementary ingredients

These are secondary components, the characterization arising from their small content in the total ink solution and not from the various functions they perform. Briefly mentioned are the ingredients contained in DTF inks, beyond the four main ones listed above:

• Surfactants → non-ionic/silicone/fluorinated wetting agents for achieving a uniform layer and controlling surface tension
• Rheology modifiers/anti-settling agents → usually mild associative thickeners, silica, polyurea at trace levels to reduce sedimentation tendency without simultaneously increasing the viscosity
• Defoamers → silicone/non-silicone, for control of microbubbles responsible for misfire(3)
• pH regulators → usually amines (e.g. AMP-95, TEA), responsible for maintaining pH of the solution within the desired range (7.5 – 9.0)
• Preservatives/Biocides & Chelating agents → MIT/BIT-free preservatives (due to regulations), EDTA or equivalents for ion binding, responsible for protection from microbial growth (odors, viscosity increase)
• Crosslinkers → improvement of wash resistance levels with thermal activation

When we talk about DTF inks, it is easy to assume that they are just another consumable, a product we purchase like so many others in the printing field. In reality, however, every bottle of DTF ink hides within it a complex balance of components and technology that determines the final result. Pigments, carrier, dispersants, and resins work in precision so that the design comes out vibrant, durable, and professional. A small error in the formulation or a poor quality choice can mean not only a low-aesthetic result but also equipment damage, increased maintenance costs, and ultimately loss of reliability towards customers.

It is therefore clear that behind the “simple” question “which DTF ink should I buy?” lies a series of critical issues: color fastness, equipment protection, production reliability, and customer satisfaction. Ink is not merely a container of liquid color; it is the core upon which the entire DTF printing process is built. For this reason, good knowledge of its ingredients and the conscious choice of quality products form the foundation for every professional who wants to stand out in the market.

Jetting(1): In the context of digital printing inks, the term jetting refers to the process by which the ability of the ink to be correctly ejected from the nozzles of each printhead is evaluated and regulated. During smooth digital printing, each nozzle sprays very small ink droplets with accuracy, speed, and stability. This term, more specifically, includes monitoring parameters such as: the shape and size of the droplets, the trajectory they follow, the firing frequency, and the compatibility of the ink with each printhead (viscosity, surface tension, temperature).

Scattering(2): This is the phenomenon in which light encounters a penetrable surface but is not transmitted in a straight line; instead, it is scattered in many random directions. Practically, in white DTF ink, the higher the scattering, the fuller, more opaque, and brighter the white appears in the final result of the print.

Misfire(3): This term denotes the “faulty” ejection of ink, where “faulty” means any jetting parameter outside the desired specifications.