Unlike a conventional colour ink, whose main purpose is to reproduce a specific colour after firing, an effect ink is intended to generate an additional response. It can modify gloss, create a localised matt finish, react with the glaze, provide opacity, reserve specific areas or enable the subsequent application of other materials.
This distinction does not mean that colour and effect are developed separately. Within a ceramic collection, both must form part of the same decorative system. The graphic, channel distribution, application sequence and glaze behaviour must all be coordinated so that the final result retains the original design intent.
Within our range of digital inks, we work with reactive, white, matt and gloss solutions, digital glues and other specific developments. All of them must maintain stable machine performance, controlled particle distribution and rheology compatible with the printing system.
How the effect develops after printing
The final effect is not always visible before firing. In many developments, it appears or reaches its full expression during the firing process.
The process begins with the controlled deposition of the ink onto the engobe, glaze or other layer defined during development. The amount applied and the position of the ink within the production line determine how it subsequently interacts with the other materials. During the thermal cycle, melting, maturation and reaction processes take place, ultimately defining the appearance of the fired surface.
For this reason, two factories may use a similar formulation and obtain different results. Variations in the glaze, body absorption, kiln curve or ink discharge can alter the intensity, definition and even the nature of the effect.
As a colour supplier, we do not analyse the ink in isolation. We study the complete system to understand which variables are creating the result and which ones may destabilise it.
What effects can be achieved with inkjet printing?
Digital decoration technologies make it possible to apply material to highly precise areas and coordinate it with the graphic. This opens up a wide range of aesthetic possibilities, although each effect requires a specific formulation and specific operating conditions.
Gloss and matt contrasts
Gloss and matt effects make it possible to modify the way light is reflected in selected areas of the piece. They can be used to highlight veining, geometric patterns, ornamental details or changes in material within the same surface.
In a stone reproduction, for example, a localised gloss effect can enhance specific mineral inclusions. In a cement-inspired collection, a matt ink can help create controlled visual irregularities without altering the entire surface.
The definition of the contrast depends on the ink, but also on the background gloss, the composition of the ceramic glazes, the amount deposited and its maturation during firing. A gloss effect applied over a highly reflective base may lose visibility. Likewise, a matt effect may become concealed if the top glaze flows excessively.
Reactive effects
Reactive inks are formulated to interact with other layers in the ceramic system. This reaction can create variations in depth, slight depressions, changes in gloss, defined boundaries or visual responses that are difficult to achieve using a colour ink alone.
Reactive effects require particularly precise control. A reaction that is too weak may go unnoticed, while an excessive response can alter the definition of the graphic or create unwanted irregularities.
It is also important to distinguish between the action of a reactive ink and other special finishes generated through glazes. Certain formulations can react with temperature or with digital decoration to produce physicochemical relief effects, metallic finishes, lustres, iridescence or microcrystals. Not all of these finishes should therefore be attributed exclusively to the ink.
White inks and opacity effects
White ink can be used to create reserved areas, increase coverage or modify how other colours are perceived over dark or variable backgrounds. It can also be used to build localised details and reinforce specific areas of the composition.
Its performance depends on the deposition capacity of the equipment, suspension stability and its integration with the preceding and subsequent layers. A high-solids formulation must maintain an appropriate particle distribution to prevent sedimentation and ensure consistency throughout the printing process.
Digital glues and selective material application
Digital glues make it possible to subsequently fix ceramic grits or other materials onto specific areas of the tile. In this way, the graphic determines where the material is deposited and where the background remains visible.
This selective application makes it easier to create textures, reliefs and changes in gloss coordinated with the image. Current decoration technologies allow graphic processing to be synchronised with targeted granule deposition, creating surfaces with visual depth and tactile richness.
The glue must provide sufficient adhesion, maintain the definition of the design and perform correctly during drying and firing. Incorrect discharge settings may result in insufficient material, loss of detail or build-up along the edges of the graphic.
What these inks contribute to product development
Special effect inks expand the visual language available to manufacturers when developing a collection. Design is no longer based on colour alone, but also on light, depth, opacity and texture.
This capability offers several advantages.
Firstly, it makes it possible to differentiate products inspired by similar references. Two collections based on marble, stone or cement can develop very different identities through the localised use of gloss, matt, reactive or material effects.
It also gives the design team greater freedom. The effect can follow a vein, appear only in specific details or vary between pieces within the same collection. Current industrial printers can work with multiple-bar configurations, different printhead models and complex graphic files, expanding the possibilities for coordinating colour and effect.
Another advantage is the increase in perceived value. A surface that reacts differently depending on the angle of the light, or that combines graphic design with materiality, conveys greater visual richness. However, that value can only be maintained if the solution is stable. A spectacular effect that is difficult to reproduce creates more problems than opportunities.
As a colour supplier, we aim to balance creativity with technical feasibility. The objective is to transform an aesthetic intention into a formulation capable of performing under real factory conditions.
Technical variables that determine the result
An effect ink may behave differently depending on the system in which it is integrated. Before adjusting the formulation, we therefore need to analyse the variables surrounding its application.
The body, engobe and glaze
The absorption, porosity and colour of the body influence how the ink is deposited and dries. The engobe and glaze then act on this base, modifying wettability, definition and behaviour during firing.
A stable engobe helps create a uniform background and reduces interference with the digital decoration. The glaze, meanwhile, determines melting behaviour, gloss, transparency and interaction with the inks. There is no universal formulation that will produce exactly the same effect on every base.
Rheology and printhead compatibility
For an ink to perform continuously, its physicochemical parameters must be adapted to the printing system. Viscosity and surface tension affect droplet formation, ejection and deposition, while particle size and distribution influence stability and printhead protection.
As a specific reference, Kerafrit digital inks have an average particle size below 1 µm, viscosities between 8 and 15 mPa·s at 25 °C, and surface tensions between 25 and 35 mN/m. These values apply to our range and must always be adjusted according to the technology, printhead and effect to be achieved.
Ink recirculation and the maintenance of a homogeneous suspension are also essential. Current printing systems incorporate solutions to reduce sedimentation, sustain high discharge levels and maintain production continuity.
Deposited quantity and application sequence
The discharge level determines the intensity and behaviour of the effect. An insufficient amount may produce a weak response. Excessive discharge may reduce definition, saturate the surface or alter interaction with other layers.
The point at which the ink is applied also matters. Depending on the desired result, it may be applied over the glaze, beneath a protective glaze or before granule application. Changing its position in the line alters its contact with other materials and therefore changes the final response.
Graphic design
The graphic file cannot be considered separately from the formulation. Resolution, screening, discharge percentage and channel correspondence must be designed according to the actual capabilities of the ink.
An area that is too dense may accumulate material. A screen that is too open may cause the effect to disappear after firing. Collaboration between design, laboratory and production teams prevents the graphic from demanding a behaviour from the ink that is incompatible with the process.
The firing curve
Ceramic inks develop their final response in the kiln. Within our range, we work with indicative temperatures between 950 and 1,200 °C, although the exact setting depends on the product, body and industrial cycle.
Maximum temperature is not the only relevant variable. Heating rate, soaking time, atmosphere and cooling also play a role. A small deviation may change the gloss level, weaken a reaction or alter surface definition.
Repeatability is not achieved by adjusting the ink alone. It comes from stabilising every variable involved in building the surface.
Common problems when working with effect inks
Problems rarely arise from a single cause. Diagnosis must therefore consider the system as a whole:
Loss of intensity when moving from laboratory to production.
The effect may weaken due to lower discharge, a change in glaze, different drying conditions or a firing curve that does not reproduce the original test.
Batch-to-batch variations.
When the result is not consistent, we review raw material stability, dispersion, viscosity, storage conditions and machine feeding parameters.
Sedimentation or blockages during printing.
Diagnosis should include the condition of the filters, recirculation, printhead compatibility and ejection consistency. A stable, uniform ink reduces downtime and helps maintain consistent decoration during long production runs.
Poor coordination between effect and graphic.
This may appear as misalignment, imprecise boundaries or material build-up. In these cases, reformulation alone is not enough: the file, resolution, bar synchronisation and application sequence must also be reviewed.
Material build-up or insufficient material in specific areas.
Incorrect screening, discharge or sequencing can create visible differences and alter the effect after firing.
When an effect is not reproduced correctly, analysing a single variable leads only to partial corrections. The colour supplier must study the ink, ceramic layers, equipment, graphic and firing process as a single system.
How we develop an effect ink for a collection
Development starts with a clear question: what should the effect bring to the surface?
Before formulating, we need to understand the desired visual result, the body, the glaze, the type of product, the available technology and the performance requirements the final product must retain. Creating a localised gloss effect for wall tiles is not the same as applying a digital glue to flooring that will undergo subsequent protection or finishing processes.
Based on this information, we analyse the complete ceramic system. We study the layers, the application sequence and the kiln curve. We then adjust the formulation and carry out tests using different discharge levels, bases and firing conditions.
Validation does not end in the laboratory. Industrial scale-up allows us to assess:
During this phase, we establish an operating window. We document the parameters that must remain under control and define tolerances so that deviations can be detected before they affect the finished product.
This support is part of the way we work as a colour supplier. We do not simply deliver an ink. We develop a solution adapted to the process and move forward together with the manufacturer, from the initial idea through to stabilisation on the production line.
What should a specialised colour supplier provide?
Choosing an effect ink should not be based solely on a visual sample. Manufacturers also need to assess the colour supplier’s ability to adapt the solution to their production conditions.
A specialised colour supplier must provide formulation expertise, in-depth knowledge of digital decoration systems and experience in the interaction between inks, glazes, granules and protective coatings. It must also be able to adapt the product to the printhead, discharge level, line speed and firing cycle of each production line.
Support during industrial trials is essential. It is in the factory that we confirm whether the formulation:
At Kerafrit, we work with a technical yet approachable mindset, adapting each development to the actual conditions of the line, body and firing cycle. Our goal is for the surface not only to perform during a test, but to maintain its aesthetic identity and performance once it enters production.
Special effect inks open up new possibilities for differentiating a collection, but their value comes from the balance between formulation, design and process. When every variable works in the same direction, an aesthetic idea stops being merely an intention and becomes a reproducible surface.
Do you have an effect in mind, or do you need to improve the stability of an existing development? At Kerafrit, we study your ceramic system and work alongside you from the first trials through to industrial validation.
