When a venerable spring water brand in Italy starts using cans with stylish decoration for the first time, you can be sure that something’s up.

For almost a century, San Bernardo water has been sold in glass bottles. But with the availability of innovative inks and varnishes, cans are increasingly cool and are opening up a world of creativity for can designers, offering a range of effects that has produced an explosion of imaginative metal packaging.

From reactive pigments to overvarnishes that can create tactile, relief effects, technology has been harnessed by engineers to help brands make their products stand out on supermarket shelves.

In last month’s issue of The Canmaker, the designers behind some of the world’s most striking packaging artwork, many examples of which had won awards in earlier Cans of the Year competitions, talked about their projects. Key to their success, they argued, was the use of highly-engineered inks, varnishes and body forming techniques that provided them with a wide palate of media and substrate with which to work.

High on their list of enablers was the range of inks that canmakers have been using to startling effect.

Probably the most eye-catching have been photochromic, thermochromic and glow-in-the-dark inks.

While some of these inks have been around for decades, their cost until recently has made them prohibitive for use in anything but short runs. Efficiencies achieved in their production and canmaking decoration techniques since have helped bring costs down. Now all the major canmakers offer ranges of design options that utilise the inks in different ways.

“The power of speciality inks is in their ability to create ‘theatre-in- the-hand’ for consumers during every purchase,” says Barry McCann and Patrick Edson, product director and marketing chief at Colorado-based ink maker CTI. “We change consumers’ behaviour by the power of our communication and their experience using our product. Speciality inks entertain, protect, inform, surprise, empathise and protect quality.”

Each of the creative inks offer distinctive design opportunities for brands, and the secret of their success is in their distinctive properties.

Thermochromic inks
Among the most spectacular are inks that react to temperature. While they’ve been deployed since the 1970s in different products, including t-shirts which change colour when worn, canmakers have unleashed a number of colour-changing design options.

Among them is Ball’s ‘spaceman’ can, a concept to demonstrate its Thermochromic Reveal product. There are two main products that achieve the effect: thermochromatic liquid crystals (TLCs) and leuco dyes.

In TLCs the crystals have two properties that work in conjunction to produce colour. First, they are always on the move, shifting into new arrangements depending on the temperature. Second, they reflect light at intensities that depend on the density of their arrangements. To the human eye, this fluctuation in reflectivity is presented as different colours.

Italy’s Acqua San Bernardo enlisted canmaker Crown to recreate the droplets design of the company’s bottles in a matte finish for its first batch of canned water

At low temperatures the crystals condense into a near solid state that prevents them from reflecting as much light, meaning they present as darker colours.

Their sensitivity to light is such that they can be harnessed to accurately indicate temperature changes within substrates on which they’re laid. That’s especially useful in some medical devices, including thermometers. Their drawbacks, however, make them generally too expensive for widespread use on cans: they lose their capacity to change with repeated use, are difficult to apply and costly to make.

Leuco dyes, on the other hand, are far more robust, cheaper and easier to manipulate, but they’re not as sensitive to light.

Essentially, they are inks that contain a pigment made from organic acids and a solvent. At lower temperatures these combine and present the pigment’s colour. At higher temperatures, however, their chemical attachments become unstable and they separate, allowing light to shine through them and presenting no colour.

This is useful when the leuco dye is laid over a stable ink of a different colour: at lower temperatures the leuco dye’s pigment is visible, but as it warms, the underlying ink’s colour is revealed.

The colour changes aren’t as precise as with TLCs but for designers they still have their creative and functional uses. On beer cans, for instance, thermochromic panels can indicate to retailers and consumers whether the content is still cool enough to be properly enjoyed. Thermochromic inks are expected to provide designers with continuing creative opportunities, according to CTI, which teamed up with another ink-making giant, INX, in 2014.

“Brands can use thermochromic ink to activate a QR code only when the beverage reaches the target cold temperature or when the beverage is taken into sunlight,” suggest McCann and Edson. “Highly functional, this prompts interaction and keeps the brand top of mind.”

Among canmakers that have manufactured packaging with thermochromic inks is Poland’s Canpack, which deployed them with award-winning results. Canpack won a prize in the Cans of the Year in 2019 for a limited edition range of beer cans that commemorated the Ice Hockey World Championships held in Slovakia. It manufactured four different designs of the aluminium cans for brewer Pilsner Urquell in which the effect was used to reveal a hidden inscription when cooled.

In this two-stage reveal image, designers played with the thermochromic properties of CTI’s ink to produce an amusing effect of an emptying beer glass as the

Photochromic ink
When ultraviolet light is shone onto photochromic inks, their molecular structure changes and they become active. In their latent state, they allow light to pass through them. But in their active state, less light can penetrate. When those molecules are pigmented, their activated state is represented as colour.

This technique was used by Crown in its cans for Coors Light released in Canada in 2017. After the brewer had made waves by deploying thermochromic inks to give an active, cool look to the snowy-mountain motif on its packaging, it went a step further to create a warmer note for its summer editions.

The canmaker created six collectible designs that brought each can to life in an array of colours. With four times more beer drunk in summer months and Canadian summers being very short, Coors’ designers were asked to pack as big a punch as possible onto the aluminium’s surface.

“Our market research has shown that one of the top drivers of consumer purchase intent is ‘packaging that stands out’,” says Coors Light’s assistant marketing manager Garrick Frittelli at the time. “This innovation … will be a key differentiator for Coors Light this summer.”

Glow-in-the-dark ink
Glow-in-the-dark pigments are nothing new – bioluminescent compounds have helped some fish exist in the murk of deep sea for aeons. Their industrial use has a long history too – phosphorescent paint is used to highlight numerals on wristwatches, for instance.

These inks contain phosphors, chemical compounds – commonly zinc sulphide and strontium aluminate – that are excited when exposed to light and begin to reflect that energy back in the form of dim light. Depending on the compound, they will continue doing so for some time after the light has been dimmed.

For designers these add novelty to a can’s appeal. Ana Neale, marketing and strategic planner at Ball, says the canmaker’s glow-in-the-dark product is being targeted at alcoholic drinks brands, which are more likely to sell their products in dark bars and nightclubs.

Coca-Cola used glow-in-the-dark technology on aluminium bottles back in 2006. More recently, PepsiCo used it to promote its Mountain Dew soda in the Middle East on cans made by Crown. Using ink made by INX, designers gave the cans an ultra-green appearance when shone beneath ultraviolet light.

The effects of fluorescent inks are short-lived, however. They are not colourfast and will fade in bright light and sunlight over time. They can also reduce the sharpness of a printed design and so can only really be used for low-definition images.

Designers have also been working with innovative overvarnishes that offer other special effects.

Coatings giant PPG’s iSense range of overvarnish effects include a reflective pigmentation that produces a sparkling appearance, a flexible overvarnish suitable for necked bottles and shaped cans, and a lacquer that produces matte and satin finishes.

PPG uses reflective ingredients in its overvarnish to produce a sparkle effect on can surfaces

Canpack used such an overvarnish for the design of Asahi-owned beer brand Plzensky Prazdroi Slovensko. The overvarnish, applied strategically on specific parts of its cans, highlighted particular elements, giving a tactile dimension to the product.

“We know that improving speciality exterior coating line efficiency is just as important as making the cans look good,” says Robyn McMillan, PPG’s global beverage segment manager. “That’s why we are developing improved, low-misting versions of our matte and satin finishes.”

PPG is offering similar effects for use in personal care products. It’s also making basecoats with more than 1,000 colour matches.

That’s where the cans for San Bernardo’s spring water return to the story. Crown worked with the Acqua S. Bernardo team when it revived a design by car stylist Giorgetto Giugiaro used on its 1994 La Giocca bottles.

Selective layers of overvarnishes were used on 330ml sleek cans made at Crown’s Parma plant, giving “a special tactile finish … creating a multi-sensory product that truly stands out on retail shelves, at the same time ensuring brand consistency”.

As PPG’s McMillan indicated, tactile effects have added a new dimension to can designs.