Using a flatbed UV-cure digital printer to decorate glass can be a little tricky, however. Still, the results are worth the extra effort and care. We reached out to some equipment suppliers and end users and asked them to look at some of the hot trends in glass printing. We will also touch on the printing process itself with tips and advice for printing onto glass surfaces.
What’s Trending?
According to Deborah Hutcheson, director of marketing at Agfa Graphics, Elmwood Park, New Jersey, UV inkjet printing is taking off in the area of décor applications for the architectural and design market. “This market is realizing the benefits of UV printing, such as high quality output, fast turnaround and customization. As a global leader in UV-curable inks, Agfa Graphics has an expertise in the sign and display market; as well as the industrial inkjet market where glass printing is being integrated into the manufacturing process of producing branded beverage bottles, for example. Here we work with systems integrators to design, develop and manufacture inkjet inks and fluids for industrial production,” she explains.
“Some examples of glass applications for UV inkjet include printed mirrors and glass signage, decorative indoor glass wall panels, shower doors, furniture glass, cabinet glass and kitchen backsplashes,” she adds.
Colorful Apps
“According to our clients, one of the most popular uses for glass printing today is for high-end, high-quality color applications,” says Shael Sacks, vice president of NGI Designer Glass, a firm specializing in glass decoration in Concord, Ontario, Canada. "From our standpoint, printing on glass has provided a unique way to give a sleek premium look to graphics. The biggest trend in glass printing right now is in indoor architectural applications. We work with designers, architects and creative people across the country to transform standard signs and other branding vehicles into stunning decorative glass panels.”
Sacks adds that based on what NGI now handles, the current most popular applications that clients are requesting include high-end decorative wall panels, backsplashes and partition walls.
Glass Growth in North America
Using flatbeds to print on glass is very big in Europe but is showing signs of catching on more vigorously in North America as well. One output provider that is seeing an uptick in this sector is Agio Imaging, a wide-format printing firm in Kalamazoo, Michigan. “We have been in this market for about eight years and we are seeing some nice increases of late. Glass printing is a growing niche market for us,” says Davina Logan, Agio's director of sales, marketing and administration. “Most of the work we are doing in this area is with high-end interiors. Using our processes, we are able to create products that are elegant, durable and green. Glass also provides a more stylish look over using acrylics.”
Personalized Applications
Heather Roden, product marketing manager, Fujifilm North America Corp., Graphic Systems Division, Hanover Park, Illinois, says that this area is becoming highly personalized in the products that can be created. “Popular applications include awards, tiles, shower enclosures, office partitions among other decorative applications. These are especially popular given this growing demand for customization and personalization.”
Second-Surface Printing
Josh Hope, senior manager, Industrial Printing Business Development & Marketing at Mimaki USA, Suwanee, Georgia, believes that second-surface printing on glass is very popular for a higher end premium product look and feel. “Second-surface printing is the practice of printing onto the backside of a transparent material where the printed artwork is viewed through the substrate itself. This is something that had been seen in advertising and P.O.P. applications, but it is now becoming more common in consumer photo and home décor applications.” He adds that personal photographs and artwork, POP displays and interior décor are all very popular right now.
“With the Mimaki Kebab MkII option for the UJF MkII Series and UJF-7151 plus printers, users can also print directly onto cylindrical glass objects such as wine bottles, beverage glasses, and vases,” Hope says.
Techniques for Printing onto Glass
Joe Garcia, managing director at StratoJet USA, Santa Fe Springs, California, says there are some specific techniques used for printing successfully onto glass with a UV-curing printer that need to be followed. “Printing on glass is one of the most visually stunning media," Garcia says. "When you print on the reverse side, the printed image bonded in glass gives a more luxurious look.”
Garcia continues, “To achieve this for a reverse print, choose the desired effect using white ink. Then, choose spot white for a combination of translucent view-thru application, such as an office divider or choose to overcoat with white for a museum display. For an even more stunning look on a thicker glass, you can print CMYK, then overcoat white turn the glass around and complement the print with a small detail. This will give a 3D look to the final print,” he points out.
Garcia adds that it is possible to print UV successfully onto glass without coating the glass first. “Customers can print on one side only and the ink will adhere, however, because glass is expensive and it is difficult to handle; customers want the maximum possible adhesion and scratch resistance, hence nearly always an ink adhesion promoter is applied before the print.”
Good Combination Between Ink and Substrate
Hope adds that second-surface printing onto glass with UV-cure inks is actually a very easy process. The key is to ensure that the ink and substrate combination provide adequate adhesion and durability. He adds that it also possible to print UV successfully onto glass without first coating the glass.
“Some printers such as the Mimaki JFX and the UJF Series printers can jet primer in the same way that it jets ink,” Hope says. “In many cases this enables users to print directly on glass surfaces without the need for pre-treatment.”
Use a Primer
Hutcheson says that Agfa suggest their customers to use a primer for the best outcome when printing onto glass. NGI Designer Glass is an Agfa customer that specializes in commercial, decorative glass, lamination and distributes these products worldwide. According to NGI’s Sacks, “From all the testing and printing we have done, a primer of some sort is required for proper adhesion of the ink to the glass. The settings are similar to those settings used to cure non-porous materials requiring lamp settings at a higher level.”
Other Output Processes
“Very often our Acuity flatbed series is used with an adhesion promotor (primer) to create some surface tension on what is typically a very smooth substrate,” comments Roden. “However, one of our customers, Epo Glass in Warsaw, Poland, uses an Acuity LED 1600 to produce stunning results with a vacuum lamination process,” she adds.
Roden says that with Epo's unique process the image is first printed onto a special roll media that is sourced direct from a manufacturer in Germany with white on the reverse. “It is then cut to shape and placed on the bed of the oven. A laminating foil is placed on top and then the sheet of glass on top of this. The oven is then switched on and cycles through a combination of heat and vacuum.
This unique process—which was established over many years of testing—was eventually patented by Epo. The print is ready after about 90 minutes in the oven. "At the end of this time, the laminating film has dissolved,” she explains. “Epo Glass has demonstrated that Fujifilm's Acuity LED and Uvijet LL printers work well with the patented process,” she explains.
More Tips and Tricks
Mike DeRuiter, partner and operator at Crop Marks in Grand Rapids, Michigan, a shop using StratoJet printers, says it is very important to start with the right glass. “Not all glass is the same. For example, thinner glass, (i.e., 1/8") often times has more thickness variation. This variation will reduce the print image quality. Have the glass supplier identify the ‘tin side’ on each piece. Most people are not aware that one side is more even than the other; the ‘non tin’ side or also called the ‘air’ side is the right side to print on,” he explains.
DeRuiter adds that to ensure that the glass is free of any oils, it should be cleaned with isopropyl alcohol and a lint-free cloth. “Add a small amount of adhesion promoter to a lint-free cloth and evenly spread across the print area. I like to use a circular motion, similar to waxing a car." He cautions that since there a number of adhesion promoters available, it's best to chose one that is recommended by your ink manufacturer in order to ensure best compatibility.
More Pointers
Stratojet’s Garcia says that when handling glass, it's a good idea to use gloves—such as Dermatril nitrile gloves. “These gloves are chemical resistant and do not generate dust particles," he says. "Gloves are used to avoid leaving fingerprints on the glass because fingerprints compromise adhesion. In addition, always set the printhead height adjustment following the manufacturers recommendation and set the UV lamp curing power to max.”
Roden says that it’s always a good idea to provide increased printhead maintenance and cleaning when printing onto reflective substrates like glass or mirror to ensure the heads continue to jet properly. UV light reflected back to the printheads can cause ink to cure where it's not wanted.
Run Tests
Hope adds the key to printing on glass with UV inks is to always test the ink and substrate combination to ensure that the proper adhesion and durability are achieved for the intended application. “Once the adhesion is established, printing on glass is no different than printing on any other substrate. One stipulation is additional precautions that would be necessary if the surface is highly reflective such as mirrored glass. In that case, it is strongly suggested to mask off any areas that are not being directly printed on, and to run maintenance cycles more often to reduce the chance of ink curing on the print heads,” he concludes.