V i s i t S G I A a t S G I A . o r g S G I A J o u r n a l ■ M a r c h / A p r i l 2 0 1 7 | 9

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By Lia Milgram, Industry Author

Growth opportunities are boundless, both for the people who develop products as well as for screen printers and ink manufacturers.

Food a nd be ve r a g e vendor s , pha rmaceut ic a l suppl ie r s , e vent planners, cosmetic companies, computer processors, marketing and advertising professionals are increasingly demanding the opportunity to print on glass to set themselves apart in the marketplace. This technology allows slogans, photographs, logos and other images to appear brighter and more vibrant. The colors pop and the image won’t fade. Printing on glass lends modernity and class to the end user’s space.

The growth opportunities are boundless, both for the people who develop products as well as for screen printers and ink manufacturers. So, too, are the challenges. Before any product can be released, special care must be taken to ensure the highest color management standards are upheld to avoid costly color mistakes.

Images printed on glass or acrylic surfaces have the unique ability to be illuminated from behind, making it hard to achieve accurate measurements

with traditional color management tools. Ref lective spectrophotometers use light that bounces off the subject to compare intended versus actual color. But since glass is itself a reflective surface, the substrate’s natural gloss effect will hinder the spectrophotometer’s ability to appropriately convey color as it is beholden to the human eye.

Instead, a transmission spectro-photometer is used to calibrate and profile wide-format digital printers for printing on glass and any other transparent substrate that necessitates backlit viewing.

When effecting color management processes using transmissive spectro-photometry, it’s important to keep in mind that measuring and managing color printed on glass encompasses certain limitations due to the thickness difference. It is possible that as the tool’s measuring head touches the glass, stray light from outside the managed area can cause incorrect readings and skew parameters

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set for dark colors. To avoid this risk of color error, it’s recommended that you stick to glass between 3 and 5 millimeters thick. A few other things to consider:

• Measure glass in the same orientation as it’s intended to be viewed. The instrument’s diffusor should be positioned at the side of the light source, and the measuring head pointed toward the print side of the glass. Setting up color management efforts in this manner will guarantee that light only streams through the patch to be measured.

• Milky, translucent glass can be measured in much the same way as fully transparent glass, but this endeavor should be undertaken at slower speeds and with more care to understand how the influence of stray light is enhanced in lower light.

• Spectrophotometers used for color management applications assume a white background as the human eye understands it to be so, and all interpretations of color are based on this supposition. Colored glass is more challenging still, rendering absolute colorimetric intent impossible. When precise color matching is required, it’s recommended that you substitute a swath of transparent glass of the same thickness.

Use of the right hardware is essential to any effective color management effort — whether printing on paper, glass or film — but so is a properly calibrated monitor. Some come out of the box with the correct properties in place, but many others do not; a monitor must be specifically calibrated and tuned to meet the color needs of the user environment, the subject matter and the intended substrate. And the task bears repeating. Even a monitor that once displayed perfectly managed color will falter. Industry color experts recommend weekly calibration upon a monitor’s introduction to the print workflow until the display stabilizes, and then again once a month.

UV InksMore and more, printers and ink manufacturers are recognizing the inherent benefits of using and developing UV-curable inks for printing on glass. UV inks comprise resins, monomers (i.e. thin, reactive liquids), pigment and photoinitiators. Upon exposure to ultraviolet light, the photoinitiators start a cross-linking chemical reaction between

Use of the right hardware is essential to any effective color management effort — whether printing on paper, glass or film — but so is a properly calibrated monitor.

V i s i t S G I A a t S G I A . o r g S G I A J o u r n a l ■ M a r c h / A p r i l 2 0 1 7 | 1 1

resin and monomer, and the result is almost instantly cured ink film.

This instant curing capability is among the chief benefits of using UV technology for printing on glass substrates. UV inks offer unrivaled color stability before as well as after curing, and on press, too. Other solvent-based inks require heating to cure and then must cool before the final color can ever be viewed. This is not the case with UV inks since they are never subjected to high temperatures.

UV inks also offer enhanced color stabi l it y during pr int ing. W here conventional inks wil l feature the evaporation of a solvent during the printing process, their UV-curable counterparts are solids-based systems, thus ensuring the color stays consistent from the start of the print run to the end.

Specially formulated for printing on drinkware, cosmetics bottles, ashtrays, vases, room dividers and other glass appl ic at ions , Marabu* deve loped technology to prove UV ink durable enough to withstand repeated exposure to high heat, humidity and harsh chemicals. Marabu Ultraglass UVGO often does require pre-treating prior to printing, with the addition of an adhesion modifier that will better prepare the surface for ink application, but in some cases UV curing alone is enough. All 13 basic shades in the Ultracolor range available from Marabu can print on glass, including special formulations, high-opacity shades, metallics and etch imitation effects. Similarly, the UV-curable, two-component UltraGlass UVGL requires no additional post baking while guaranteeing highest resistances, according to the manufacturer.

The use of UV-curable inks, combined with the most accurate management equipment and tools, enables maximum color capability, superior production efficiency, and anyone seeking to leverage the opportunity and benefits presented by printing on glass the ability to do so.

ReproductionYour color is matched and your product is shipped. It’s time to start anew, but with what reference point? Consistent color matching from one batch to the next is important at every stage in the supply chain — a concern not limited to color efforts as they relate to printing on glass. How do you reproduce the color when it’s needed again? How is ink inventory tracked? How can you most effectively estimate the amount of ink needed for the next two print runs, or four?

The answer is this: digitally, and with the aid of a properly calibrated spectrophotometer. Managing an efficient supply chain for a major cosmetics retailer with brand standards to uphold requires precise color specifications communicated between the designer, the ink formulator, the manufacturer, the package developer, the marketing team — everyone. And it all starts with color management.

Digita l color communication is inherently necessary and can be a challenge made easier with the aid of automation. Digital colors can be specified and stored within software and devices to ensure that perfect color matches occur during every step of the manufacturing process.

Software systems built into today’s most advanced printing technology enables the color minded to gauge ink levels and consumption, and re-order as necessary to streamline color management. This software is designed to make your jobs easier, offering:

• Electronic formula storage: Specific details about which colors were used for which projects can be input directly for easy reproduction at a later date.

• Inventory management: With this tool, supply chain managers can enter and view current inventory levels, set minimums and enter cost and duration data. The information gathered can then be used to determine the approximate cost of new color mixing and to predict when ink should be reordered.

• Formula editing: The ink formula that renders beautifully on paper or film might, at first pass, appear dull or just not quite right when printed on glass. Advanced system software allows the user to edit an existing formula to suit a new need, and then to save the differently fashioned formula for future use.

Working alongside and in conjunction with intel ligent color management software, certain hardware is equipped to dispense ink automatically depending on the particular needs of a given print project. Gravimetric or automatic dispensers release ink by weight over volume, and are accurate to 0.1 gram. Such dispensers have the capability to dispense color on demand in as little time as minutes, thus reducing the number of pre-blended colors a print shop must keep on hand. This enables a more efficient print-on-demand model and provides significant inventory and labor savings.

The use of UV-curable inks, combined with the most accurate management equipment and tools, enables maximum color capability and superior production efficiency.

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Alternatives to Printing on GlassGlass is risky. It breaks. It scratches. People use harsh cleaners that can damage the integrity of glass-printed images displayed in office buildings and their homes. So what can be done?

Printers and professionals who desire the look of regular printed glass with less risk opt to laminate, or sandwich the print between two panes of glass.Doing so protects the image from the elements and virtually eliminates the need to prime or heat-cure the surface before treating, making this a viable and time-saving alternative for anyone without immediate and easy access to UV inks. Take special care, though, to laminate the glass carefully to prevent scratching or otherwise damaging the image. With this method, it’s important to note that condensation, on occasion, will creep through the layers as environmental conditions change.

Some of the conscientious or risk-averse printers might even choose to print on thin, flexible film, which can then be placed between two individual pieces of glass. This method of laminating glass has benefits beyond ensuring color once measured and managed remains, but also adds an additional layer of safety within the glass itself; if one pane breaks, the other remains steady. Printers and end users whose applications include curtain walling, windows or skylights often choose to achieve a printed glass effect through lamination.

ConclusionFrom coast to coast, everyone printing on glass shares a common concern: to get the color just right. And SGIA members are making that happen. Consider this — in June of 2009, a small, family-owned brewery based out of Greenville, South Carolina started on a new path. Holding true to their stated mission of, “Don’t be typical,” Thomas Creek Brewery LLC became the first recognized bottler to print directly onto its glass packaging materials using Uvaclear technology developed in part by INX International*.

This system uses singular, UV-curable ink applied using a high-speed screen printing process. Ink is cured and dries instantly, and it’s environmentally friendly too. Thomas Creek Brewery bottles are f lame-treated to remove any coating applied during manufacturing, pre-washed to optimize ink adhesion and then fed directly into the press, where ink is applied and then exposed to UV light to cure in a fraction of a second.

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But first, the color must be managed. Brand experts at Thomas Creek Brewery communicated directly with art and print partners to provide instruction. Included among separate color screens produced for each, the direct-print label features a specific, Pantone-coded yellow, a black background and white ink. The beer might be good — but without proper color, the bottles would fall flat.

UV-curable inks are growing steadily in their popularity among those interested in printing directly on glass for decorative, home, commercials and industrial uses — thanks to their supreme color stability

and range, fast curing speeds with little or no heat required, vast environmental advantages, and special effects capabilities, too. This revolutionary technology combined with the most accurate, effective color management tools and equipment can open new doors into new product streams for imagers everywhere.

*SGIA Member, in order of mention:Marabu, since 2000INX International, since 2006

Lia Milgram is an editor and a writer.

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