DIGITAL PRINT IN METAL DECORATION

Digital printing has become one of the most discussed technologies across packaging segments. However, until recently, metal decoration remained a slow adopter. This has been limited by the demanding performance profile of metal cans and the high application demands of stoving, forming, filling and handling. 

Thanks to significant advancements in inks, primers and coatings – alongside rapid hardware and software developments – digital print is now emerging as a commercially robust and strategically important technology for three-piece can manufacturers, original equipment manufacturers (OEMs) and brand owners. For brands and packaging producers seeking greater agility and OEMs looking to expand the capability and value of their metal decoration platforms, such technical innovations represent a breakthrough moment for digital printing in metal decoration.

While metal packaging remains fundamentally about protection and durability, brand owners increasingly view the can as a strategic communication surface. Digital printing offers a set of advantages that align with the current pressures facing both brands and OEMs:

Simplified Short Runs – Until recently, short runs for metal-packaging applications was considered anything below 15,000m2. Today, increased numbers of stock keeping units (SKUs), localised campaigns and seasonal editions are the norm. Digital printing eliminates the need for printing plates, reduces set-up time and makes short runs economically viable even at 1,000–5,000m2.

Faster Design Cycles – Brands can iterate artwork rapidly, moving from concept to production in days, rather than weeks. This is something that analogue systems simply cannot match.

Sustainability Advantages – Inkjet-printing solutions offer lower energy consumption resulting from shorter set-up needs, minimised over production and printing closer to the market. In this way, delivery distances are reduced and so transport energy and emissions are lowered. Additionally, digital print enables reduced waste with no plate-making requirements, minimised make-ready and print on demand (POD) for more efficient inventory management. Furthermore, over production is reduced, resulting in discarding unused materials. Adopting inkjet printing may also result in a lower chemical load for the application. It offers a wider range of aqueous solutions, less solvents in cleaning and a reduction in the chemicals needed in the creation of printing plates. For OEMs building next-generation lines, digital modules reduce environmental impact and can support evolving regulatory expectations. 

Customisation and Differentiation – Whether through limited editions, promotional packaging/on-the-shelf marketing or test market batches, digital print creates new value propositions that analogue print processes struggle to serve economically. 

However, digital printing for metal decoration has historically been constrained by one major challenge – performance. The inks needed to survive stoving at 140°C+, forming, sterilisation, water contact and harsh chemicals – conditions beyond many digital inks.

Today, the majority of digital metal decoration printing is done using UV and UV-LED inks in combination with a primer and, in most cases, a post print coating. This established workflow has driven the implementation of inkjet technology and become the standard, achieving excellent print quality and application performance. 

Whilst the success of UV-ink technology is significant, there is a market pull to explore whether water-based inks could achieve the same performance. This could potentially increase the adoption of digital printing due to lower compliance challenges. For example, in relation to lip contact.

To enable water-based solutions to penetrate this demanding space, Sun Chemical has been innovating primers and inks to deliver equivalent application performance.

A critical enabler in the journey towards reliable digital metal decoration with water-based inks is the introduction of a thermal curing, flexo applied reactive primer designed specifically for metal sheets. This primer – co-developed with specialist resin developers – increases image formation and downstream physical robustness. The key technical breakthroughs are as follows:

Reduced Dot Gain and Cleaner Ink Lay Down – Trials show enhanced dot control, less inter-colour bleed, delivering more vibrant prints.

Significant Uplift in Water Resistance – Even prints dried at just 70°C demonstrate strong water resistance. This is a major step in making aqueous inkjet suitable for three-piece can lines. 

Designed for Both Analogue and Digital Lines – The primer supports hybrid operations, giving OEMs flexibility in equipment design and allowing decorators 
to adopt digital incrementally.

This development is underpinned by patented chemistry.

For OEMs, this approach represents a stable foundation chemistry that opens the door to integration of digital modules within existing metal decoration workflows.

For heavy duty metal applications, alongside the reactive primer, thermally curable aqueous inkjet inks have been engineered to cross-link under the same high temperature stoving conditions already used in metal decoration.

This creates a transformative combination – the safety and sustainability profile of aqueous technology with the performance traditionally associated with UV systems.

Exceptional Solvent Resistance – The new process can achieve excellent solvent resistance, including against ethanol and methyl ethyl ketone (MEK). This is a benchmark that historically kept aqueous technologies out of metal decoration. The patented technology, inducing cross-linking at temperatures greater than 125°C, is a breakthrough enabling technology for metal decoration.

High Resistance Without an Overprint Varnish (OPV) – The synergy between primer and ink raises the possibility of reducing the need for an OPV for some applications. This simplifies line design and reduces operational costs.

Printhead Safe – Experimental formulations dissolve in flush within 60 seconds, balancing performance with printhead lifetime.

Flexible Under Forming Conditions – When printed over conventional base coats and varnished, the inks show excellent performance during sterilisation. This results in no frosting, no peeling, stable adhesion and good flexibility, even through deep draw processes (a potential further application space). This is partially achieved by having a much lower dried film weight than UV-inkjet prints which also results in a visual appearance much closer to offset printed cans.

This combination of durability, flexibility and safety may represent a turning point for digital-ready OEM platforms.

The quantitative improvements emerging from the development work illustrate how far aqueous systems have progressed.

For brands and packaging manufacturers, this means digital print now meets the chemical robustness required for canned foods, aerosols and industrial contents.

For OEMs, it means digital systems can be engineered confidently into high performance metal decoration lines.

These developments can further strengthen the argument for digital print in metal decoration applications for both OEMs and brands.

Hybrid Lines Become More Attractive – Digital units can be inserted before or after analogue stations or alongside existing offset presses, enabling parallel benefits.

Modular Upgrades – OEMs can offer digital add-ons, creating new after-market revenue and expanding equipment life cycles.

Greater Automation and Workflow Integration – Digital dovetails with file-to-print workflows, inspection technologies and inline quality control systems. This offers packaging manufacturers more flexibility in production and inventory management.

Sustainability As A Differentiator – Aqueous digital systems help OEMs create future-proof lines that align with brand sustainability commitments.

Brands are looking to increase agility, reduce reliance on inventory and stagnation of cash flow, as well as opening up the potential for customisation and consumer connections. Digital print is supporting these goals.

Mass Customisation – From regional campaigns to influencer collaborations and promotional series, brands can execute diversified artwork without the penalty of analogue setup.

Faster Time to Market – Rapid SKU changes support agile marketing, faster trend adoption and reduced inventory.

Reduced Waste, Smaller Minimum Orders – Digital supports short runs and test batches, reducing obsolete stock and improving sustainability.

Premiumisation and Value Creation – Sharper graphics, special editions, consumer connection to loyalty programmes or engagement projects and highly tailored packaging elevate brand presence on shelf. This is vital in today’s competitive fast-moving consumer goods (FMCG) categories.

Development of new reactive primers and self cross-linking aqueous inks expands the potential for digital-print adoption in metal decoration. The technology aligns with the performance, compliance and efficiency needs of both OEMs and major brands.

Sun Chemical, through collaboration of digital ink, primer and metal decoration teams, has developed technology platforms to support the potential for digital print to increase share within this key packaging category. Together with hardware partners, the three-piece beverage can looks set for wider digital adoption with further inroads possible into two-piece cans and deep-draw metal packaging. The benefits for OEMs, packaging producers and brands are tangible. The value of inkjet is a reality today, not just for the future. For more information, visit www.sunchemical.com/packaging

To further explore the potential of digital printing for three-piece cans, Sun Chemical invites readers to visit Stand 3A39, Hall 3 at Metpack in Essen, Germany, from 5–8 May.