The molecular recipe: How algae, soy and high-tech are rewriting ink production

Ink typically accounts for less than five per cent of a package's total weight. Yet its composition directly affects recyclability, compostability and toxicological safety. Strict EU regulations are forcing manufacturers to rebuild the chemical composition of their products from scratch. So, how is industrial printing ink actually made? A look inside the ink production facility reveals how agricultural and biotech methods are replacing traditional processes.

Every functioning ink system is a highly precise setup built on four main components:

• First is the carrier medium. Water, solvents and reactive diluents then manage the logistics. These keep the ink fluid enough to travel smoothly from the duct, across the roller train or printheads, and directly onto the substrate.
• Resins or oligomers form the structural backbone. Once the ink hits the material, these binders anchor the solid elements into the surface and cure into a highly resistant film. This layer must be able to withstand significant mechanical stress later on. If it fails, the ink will chip off during folding, die-cutting or stacking.
• Pigments provide visual impact. To achieve full brilliance, these microscopic solid particles must be completely evenly distributed in the liquid matrix without clumping together.
• Highly specific additives are then used to finish the job. Waxes, defoamers and drying accelerators often represent only a small part of the recipe. Yet they are the deciding factor in real performance on the shop floor. They prevent ink from foaming in the units, optimise flow properties, and ensure that the printed sheet is completely dry by the time it reaches the next station, even at maximum press speeds.

Classic water-based or UV-curing inks are produced through a rigorous mechanical process. The biggest physical hurdle here is the pigment. Unlike soluble dyes, pigments are insoluble solid particles (complex organic or inorganic compounds) that do not melt. They determine the opacity and lightfastness of the final print. However, they usually arrive at the factory as hard, baked-together blocks of powder.

To break them apart, the industry relies on agitator bead mills. These machines contain microscopic zirconium oxide beads that rotate with immense kinetic energy. These beads smash the clumps into primary particles through extreme shear forces. The resulting friction heat is substantial and requires specialised cooling jackets to stabilise the machinery. Only after this intense milling process is the highly concentrated paste diluted with further solvents to meet the final press specification.

UV-curing inks use reactive monomers, such as TMPTA, as solvents. These do not evaporate during the printing process. Instead, they instantly cross-link with the resin under UV light to form a solid polymer film.

The physical problem arises at the end of the product's lifecycle, during paper recycling. Recycling plants rely on flotation to separate old ink from the fibre. The process is straightforward: air bubbles rise through a large volume of water and paper. The ink particles are supposed to attach to these bubbles, float to the surface, and be skimmed off as foam.

However, this method fails completely with the cured UV film. The highly resistant acrylate network shatters into large, rigid flakes when the paper breaks down. These flakes are simply too heavy and flat for the air bubbles to carry them upwards. They fall back into the fibre mass and reappear later as black dirt specks in the new paper. 

Water-based inks present a different physical challenge. They fragment into such tiny, water-loving particles that they completely ignore the rising air bubbles. They bind directly to the water, turning the entire recycling bath irreversibly grey.

Soy-based inks offer a biological alternative. While the production of traditional ink relies on petrochemical supply chains, the production of soy ink starts in the field. Harvested beans are rolled into flakes by industrial machines, which then extract the oil using hexane. The raw soy oil then needs to be stripped of waxes and mucilage, which would otherwise disrupt the printing process.

The crucial difference lies in the drying behaviour. Soy oil does not evaporate. Instead, the ink dries through slow oxidative cross-linking with oxygen in the air. However, this natural process is far too slow for industrial press speeds, so manufacturers add metallic catalysts. For environmental reasons, the industry is moving away from the use of toxic cobalt and replacing it with iron or cerium salts. This makes balancing the chemical formulation more difficult. Soy inks perform brilliantly during paper recycling because they detach easily from the fibre. However, they are not perfect: fatty acid residues can cause resinous discolouration in the newly formed paper.

Algae-based inks represent a significant departure from traditional production methods. They replace the most problematic element of black ink, the fossil-based pigment carbon black. Rather than cracking crude oil, industrial farms cultivate cyanobacteria or green algae.

Pyrolysis is the key technology in this process. Reactors heat the dried algae mass to extreme temperatures in an oxygen-free environment. Without oxygen, the plant structure cannot burn. It carbonises into a pure black powder. This process locks in the CO₂ that the algae absorbed while growing. Therefore, the pure pigment achieves a carbon-negative balance of -4.16 kg of CO₂ equivalent per kilogram – a unit of measurement that compares the impact of all greenhouse gases to that of CO₂.

In order to reduce historically high production costs, manufacturers are heavily promoting vertical integration. They are building pyrolysis plants directly at biomass collection points. Biological waste streams, such as spent yeast, are now also being fed into the reactors, significantly reducing the cost and increasing the flexibility of pigment production.

In recent years, crucial breakthroughs have been made in running algae inks on industrial presses. The combination of organic algae pigments and reactive UV chemistry was previously deemed incompatible with high-speed printing. However, flowable UV algae inks can now be used successfully in conventional doctor blade systems for narrow-web UV flexo printing. Using black algae ink for beverage labels reduced the carbon footprint from 4.27 kg to 1.66 kg of CO₂ equivalent.

The transition to the CMYK colour space is also becoming more feasible. Algae naturally produce vibrant colours, such as the blue protein phycocyanin. Previously, these proteins would disintegrate under the heat of industrial processing. However, researchers have now stabilised phycocyanin at the nanoscale in emulsions, maintaining its brilliance even under severe thermal stress.

This development could not be more timely. Legislation is forcing ink manufacturers to change the materials they use. For example, Switzerland will mostly ban 'Part B substances' (chemicals lacking comprehensive toxicological evaluation) in food packaging from 2026. The industry must therefore quickly replace established resins with fully evaluated alternatives. This will greatly accelerate clean, bio-based production runs. 

Ecological mandates are no longer holding back the printing press. Although optimised recycling processes are making classic UV and water chemistry cleaner, biotech approaches offer a genuine departure from the fossil past. Today, ink offers much more than just shelf appeal. It is a powerful tool for decarbonisation, determining whether packaging is burned as waste or remains a clean resource in the circular economy.