Flexography is a high-speed printing method that uses flexible raised plates to transfer ink onto almost any material, from plastic food wrappers to corrugated shipping boxes. It dominates the packaging industry because it prints quickly on surfaces that other methods can’t handle well, including films, foils, and non-porous plastics. Modern flexo presses reach speeds up to 800 meters per minute (about 2,600 feet per minute), making it one of the fastest commercial printing technologies available.
How the Process Works
Flexography follows the same basic logic as a rubber stamp, but at industrial scale and with precise ink control. The process breaks into three stages: prepress (preparing the plates and artwork), press (the actual printing), and post-press (cutting, folding, or rewinding the finished material).
On the press itself, ink moves through a short chain of rollers before reaching the material being printed. First, ink feeds onto a specially engineered roller called an anilox roller. This roller is covered in millions of tiny cells, each one holding a precise amount of ink. The anilox roller then transfers that controlled ink layer onto the flexible printing plate, which carries the raised image. Finally, the plate presses against the substrate (paper, film, foil, or whatever is being printed) and deposits the image. For web presses, the most common type, substrate unrolls from a large roll at one end of the press and collects on another roll at the other end after printing is complete.
The Anilox Roller: Flexo’s Secret Weapon
What sets flexography apart from other printing methods is how it controls ink. The anilox roller is the critical piece. Its surface is engraved with microscopic cells, and the volume, depth, and shape of those cells determine exactly how much ink reaches the plate. A higher cell count with smaller cells produces thinner, more precise ink layers for fine detail work. A lower cell count with larger cells deposits more ink for bold, saturated coverage.
Getting this right matters enormously. If the cells deliver too much ink, the image floods and loses sharpness. Too little, and colors look washed out. Printers select different anilox rollers depending on the job, essentially swapping out rollers to change the ink film thickness without reformulating the ink itself.
Printing Plates
Flexo plates are made from photopolymer, a light-sensitive plastic that hardens when exposed to ultraviolet light. The platemaking process starts with a digital file of the artwork. A laser images a mask on the plate surface, exposing only the areas that should be raised (the printing areas). UV light then cures those areas into solid, flexible rubber-like material, while the unexposed portions wash away during development, leaving the raised image behind.
Plates can be developed using solvents or thermal processing. The flexibility of the plate is what gives flexography its name. Because the plate bends, it wraps around a cylinder on the press and conforms to uneven surfaces like corrugated cardboard without crushing the material.
Print Quality and Resolution
Flexography used to have a reputation for fuzzy, low-quality output. That’s changed significantly. High-definition flexo now achieves plate screen rulings of 175 lines per inch (lpi) or greater on narrow-web presses and 150 lpi or greater on wide-web presses, according to the Flexographic Technical Association. For context, many magazines are printed at around 150 lpi. This means modern flexo can reproduce photographic images, fine gradients, and small text with clarity that rivals offset lithography for most packaging applications.
What Flexo Can Print On
Versatility with substrates is one of flexography’s biggest advantages. It handles porous materials like paper and cardboard as well as non-porous surfaces like plastic films, metallic foils, and cellophane. This range makes it the go-to choice for food packaging, beverage labels, shipping boxes, gift wrap, and plastic bags.
Research is pushing the boundaries further. Scientists have demonstrated flexographic printing of functional nanoparticle inks (silver, zinc oxide, and others) onto rigid and flexible substrates, including PET films. This opens doors for printing electronic components like sensors and circuits onto everyday materials, potentially landing flexo technology on surfaces like contact lenses and ultrathin membranes.
Three Types of Flexo Ink
Flexographic inks fall into three main categories, each with a different drying method and set of trade-offs.
- Water-based inks use water as their primary carrier. They’re the most environmentally friendly option since they produce very low emissions. The downside is speed: water-based inks dry about 4.5 times slower than solvent-based inks because water evaporates more slowly. Small amounts of alcohol are often added to improve drying. These inks work best on porous substrates like paper and cardboard, where the material itself absorbs some of the moisture.
- Solvent-based inks use organic solvents that evaporate at room temperature, producing a fast-drying result. They adhere well to non-porous surfaces like plastic films and foils, which is why they’ve been widely used in flexible packaging. The major drawback is environmental: the evaporating solvents release volatile organic compounds (VOCs) into the air, requiring expensive exhaust treatment systems to meet air quality regulations.
- UV-curable inks contain no solvents at all. Instead, they stay liquid until exposed to ultraviolet light, which triggers a chemical reaction that hardens the ink into a solid film within fractions of a second. Because nothing evaporates, there’s no VOC problem. UV inks produce vibrant, durable prints, but the press must be equipped with UV curing lamps, and the inks themselves cost more.
Environmental Impact and the Shift to Water-Based Ink
Solvent-based flexo inks used to be the industry standard, and they created serious air quality problems. A typical solvent-based flexo ink is about 50% VOCs by weight. One EPA case study documented a flexographic printer that switched entirely from solvent-based to water-based inks and reduced its VOC emissions by 99% over seven years. Had the company stayed with solvent inks, it would have been emitting over 100 tons of VOCs annually.
Water-based ink formulations have also improved dramatically. In 1989, water-based flexo inks still contained 10% to 12% VOCs by weight from additives like dispersants and surfactants. By 1996, that figure had dropped to 0.71%. Manufacturers are now developing completely VOC-free dispersions. The EPA’s Design for the Environment Flexography Project has evaluated all three ink technologies to help printers choose options that balance performance, worker safety, and environmental impact.
When Flexo Makes Economic Sense
Flexography requires upfront investment in plates and press setup for every new design. Each color needs its own plate, and every change in graphics (a different flavor label, for instance) means making new plates. This setup cost is significant for small jobs but becomes negligible when spread across thousands or millions of impressions.
This is where the comparison with digital printing matters most. Digital presses need no plates and virtually no setup time, making them cost-effective for short runs and frequent design changes. But digital presses are slower. As run length increases, flexo’s superior throughput speed overtakes digital’s setup advantage, and the cost per unit drops well below what digital can match. Every product has a crossover point where flexo becomes the cheaper option. For high-volume packaging like snack bags, beverage cartons, or shipping labels printed in the hundreds of thousands, flexo is almost always the more economical choice.
The combination of speed, substrate flexibility, and falling cost-per-unit at scale is why flexography accounts for the majority of printed packaging worldwide. If you’ve picked up a cereal box, peeled a label off a shampoo bottle, or opened a corrugated shipping box today, you’ve probably already held a flexo-printed product in your hands.