The production of chromatically customized sequins for the fashion & luxury sector does not involve decorating the finished micro-element, but rather flexographic roll-to-roll printing on reflective polyester (PET) film supplied in rolls. The continuous film is unwound, guided, printed and rewound after air drying; only subsequently is the colored web transferred to the mechanical die-cutting stage. This process ensures perfect reproducibility of the color palettes required by haute couture brands.
Introduction: the role of roll-to-roll printing in textile decoration
Within the production of accessories and trimmings for the fashion and luxury industries, sequins represent an essential decorative element for creating light effects, reflections and three-dimensional effects on fabrics. However, from a process engineering perspective, the aesthetic quality of the final sequin depends directly on the processing stages that precede the forming of the individual element.
In contemporary industrial processes, the color customization of reflective polymer films, primarily PET, is achieved through high-precision flexographic printing lines operating in roll-to-roll mode. The printing process applies the pigment to the continuous web before it is transferred to the die-cutting units.
Analysis of the technological process and machine dynamics
The dynamic analysis of the process using industrial narrow-web flexographic lines highlights a highly controlled kinematic sequence, which is essential for preserving the optical properties of the plastic substrates:
- Unwinding and tension control: The virgin roll of metallized or reflective PET is fed while maintaining constant web tension through electronic torque-control systems.
- Web guiding and electrostatic neutralization: The thin film passes through web-centering devices and antistatic bars to eliminate surface charges, preventing dust attraction that could compromise the uniformity of the ink deposit.
- Color transfer (flexographic printing unit): The ink is metered by means of anilox rolls and managed through enclosed chamber systems with continuous recirculation. The flexographic plate transfers the color formulation onto the film under precisely controlled, micrometric pressure.
- Hot-air drying: The printed substrate passes through a hot-air or UV/EB drying tunnel, depending on the ink’s chemical formulation, allowing rapid solvent evaporation or cross-linking without thermally affecting the dimensional stability of the PET.
| Process parameter | Typical technical specifications | Impact on final product |
| Printing substrate | Reflective / metallized PET film (20–100 µm thickness) | Gloss, rigidity and light refraction of the sequin |
| Web width | Narrow web (75 mm – 180 mm) | Optimization of die-cutting yield |
| Printing technology | Enclosed-chamber flexography (solvent- or water-based) | Coverage, uniformity and adhesion to the polymer |
| Line speed | 50–100 m/min | Thermal and tension consistency inside the tunnel |
| Downstream process | Micro-geometrical die-cutting | Definition of the sequin’s external profile |
Color customization in haute couture
In the luxury and haute couture segment, color is not simply an aesthetic variable, but a defining characteristic of a brand or a specific seasonal collection. The technical specifications imposed by fashion houses require extremely tight color tolerances.
Continuous flexographic printing on PET film meets this requirement through several strategic factors:
- Development of custom shades: Formulation of transparent or semi-opaque inks specifically developed to interact with the metallized polyester background, creating enhanced metallic, iridescent or satin effects.
- Longitudinal and transverse uniformity: The constant ink supply provided by the enclosed chamber ensures that color saturation remains identical from the beginning to the end of the roll.
- Inter-batch repeatability: Standardization of the printing plate (polymer plate) and anilox cells ensures precise color matching between collection replenishment runs carried out over time.
When the printed roll is die-cut, each individual micro-element inherits a portion of the surface that is chromatically identical to all the others. Applied in thousands of units to a garment, the sequins therefore produce a perfectly homogeneous visual surface, free from tonal variations or color mismatches.
Optical interaction between reflective film and ink layer
A critical aspect of engineering this process lies in the optical properties of reflective PET. Unlike opaque substrates, the final color response is determined by the combined interaction of two components:
- Specular reflection of the underlying substrate: Light passes through the dried ink layer, reflects off the mirror-like surface of the PET and passes back through the printed layer toward the observer.
- Refraction through the polymer ink layer: The nature of the ink resin determines its refractive index as well as the pigment’s resistance to mechanical abrasion and textile washing.
For this reason, the flexographic technology employed must ensure the deposition of a perfectly controlled color film thickness, often in the micron range, free from micro-bubbles or streaks that could generate abnormal light refraction after the sequins have been punched.
Sustainability and new materials: recycled PET (rPET)
The evolution of European environmental regulations and the fashion industry’s shift toward a circular economy have led to the introduction of certified rPET films, i.e. post-consumer recycled polyester, such as materials compliant with the GRS (Global Recycled Standard).
Flexographic printing on rPET involves additional engineering challenges:
- Variable surface tension: Recycled films may exhibit variations in wettability, requiring in-line Corona treatment integrated into the printing press.
- Mechanical resistance during die-cutting: Ink adhesion to the recycled film must be excellent in order to prevent flaking along the cutting edge during high-speed sequin punching.
How is color applied to fashion sequins?
The color is applied directly to the continuous reflective polyester (PET) film through roll-to-roll flexographic printing. After the ink has been dried and the roll rewound, the printed film is transferred to the die-cutting stage to produce the individual sequins.
What are the advantages of flexographic technology for this sector?
Flexography provides high production speeds, micrometric control of ink film thickness, exceptional color saturation on metallized substrates and excellent color repeatability for production intended for the luxury market.
Is the printing process compatible with recycled PET (rPET)?
Yes, subject to verification of the film’s surface tension and, where necessary, the application of in-line Corona treatment to ensure proper chemical and physical ink anchorage before the die-cutting operations.
Technical glossary
- Roll-to-roll (R2R): A continuous processing method in which the material passes from an unwind roll to a rewind roll through intermediate processing stages.
- Reflective PET: Polyethylene terephthalate film subjected to aluminum coating or vacuum metallization to provide mirror-like reflective properties.
- Anilox: A ceramic roll engraved with laser-etched micro-cells, used in flexographic printing to precisely meter the volume of ink transferred to the printing plate.
- Die-cutting / punching: A high-precision mechanical cutting operation that transforms the printed film or sheet into the final geometry of the decorative micro-element.
Illustrative guide to Modular™ 965 flexographic printing equipment
Modular™ 965 equipment (model F965-FS-01), manufactured by Giugni s.r.l., is a roto-flexographic printing machine developed for one-color printing on polyethylene terephthalate (PET) film. Designed to provide maximum precision and industrial efficiency, it combines an advanced ink recirculation system, hot-air drying units and a touch-screen control interface designed for Industry 4.0 integration.
1. Architecture and main components
To understand the operation of the machine, it is essential to examine its layout both on the operator side, where machine operation and film travel take place, and on the drive side, dedicated to ventilation and web transport.
General view – Drive side
The operator side houses the unwinding and rewinding units, the touch-screen console, the printing unit and the web tension control systems.
General view – Motor side
The rear section of the machine contains the power and ventilation systems, responsible for air extraction and thermal management during the drying process.
2. Printing unit and enclosed chamber
The core of the equipment is the printing unit, consisting of the impression roll, the ink roll (Anilox) and the enclosed chamber system.
The enclosed chamber
The enclosed chamber distributes the ink uniformly across the anilox roll while preventing splashing and residual ink. It is equipped with doctor blades, sealing gaskets and anti-drip quick couplings for ink supply and discharge.
3. Ink recirculation unit
Ink is supplied by a diaphragm pump, which draws the ink from the dedicated container and delivers it to the enclosed chamber, while a second pump handles the return flow. The system includes a reverse function that is essential during emptying and cleaning operations.
4. Installation, loading and film path
Roll loading
To position the film roll, it must be mounted on the expandable shaft at the correct distance and secured by supplying compressed air through the dedicated nozzle.
Film path
The unwound film passes through the dancer rolls, the antistatic bar and the inlet web guide before being printed between the impression roll and the printing plate, and finally enters the drying tunnel.
5. Physical and touch-screen control panel
The operator interface is divided between the physical control panel integrated into the machine side frame and the touch-screen control panel.
Physical control console
The side-mounted console allows immediate control of material feeding, drive motors and emergency stop functions.
Touch-screen interface
Through the touch-screen panel, the operator can monitor production data, configure machine start-up, activate the ventilation system and manage system alarms.
| Home menu (job parameters) | Print start-up menu |
| Initial roll diameters, production length and speed settings | Activation of RACK, grinding and recirculation pump |
| Ventilation and tunnel management | Industry 4.0 module |
| Temperature adjustment and tunnel closure | Job interfacing and production-time monitoring |
6. Fine adjustments and maintenance
Printing pressure adjustment and graduated indicators
To ensure high-quality printing without deforming the film or damaging the printing plate, the printing pressure is adjusted using dedicated handwheels equipped with graduated indicators.
Calibration note: Each graduation indicated by the red arrow corresponds to a 0.01 mm adjustment. A complete 360° rotation produces a 1.00 mm movement.
Enclosed chamber alignment
Ensure that the enclosed chamber is perfectly parallel to the axis of the ink roll (Anilox). Incorrect pressure or misalignment may result in ink leakage or premature wear of the doctor blades and sealing gaskets.
Doctor blade maintenance and gasket replacement
During routine maintenance, after the enclosed chamber has been emptied and disassembled, the condition and wear of the doctor blades and sealing gaskets must be inspected.
Roll-to-roll flexographic printing on PET film represents an effective solution for the production of sequins intended for the fashion and luxury sectors. Precise control of web tension, ink, printing pressure and drying conditions ensures color uniformity, aesthetic quality and repeatability across different production batches. The evolution toward the use of rPET also demonstrates the potential to combine industrial performance, technological innovation and a stronger focus on sustainability.
Discover the Modular™ 965, the Giugni® solution designed for flexographic printing on PET film, ensuring precision, color uniformity and process continuity in the production of sequins for the fashion and luxury sectors.
Written by Gian Pio Giugni – President of Giugni S.r.l., 40 years of expertise in Flexographic Technology | Team Giugni®
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