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Ceramic frit ink (inorganic pigments), UV-cured, or sol-gel inks for digital printing on glass?
Which inks for digital printing directly on glass is the big question still in 2010 and as we move into 2012. Since many of our readers are print shop owners, manages, and printer operators around the world, they come to ask FLAAR for assistance in deciding which wide-format inkjet printer should they buy so they can skip screen printing and print directly on glass. Since our background at FLAAR is with architecture, we too are interested in printing on architectural glass. The world of wide-format digital printing is a world of fast printing of usually customized images, usually for short runs. A trade show booth may need glass walls, or glass table top. Or a restaurant may wish to have their logo on their windows (directly on the glass, not on roll-fed material adhered to the glass with an adhesive layer). UV-cured wide-format inkjet printers have traditionally been used for small print jobs such as these. Or an architect may wish an entire building to have a custom appearance on the glass façade. In the past, if you wanted long-runs of hundreds of examples or thousands of square meters, then you utilize screen printing, offset printing (for signage), pad printing, or flexo printing (for packaging, for example). But today in-line production printing is also realistic with inkjet chemistry. But today in 2010 and going into 2011, there are many competing inkjet ink chemistries. Each has several advantages but each ink chemistry has one or two things it can't handle well. So it is essential to compare and contrast the different ink and wide-format digital printer options. If you need in-line printing on glass, this is a separate world of industrial printing. Durst would be an example for in-line printing on other materials (for printing on ceramic tiles, in-line or their printer for wooden décor). I have been to the Durst factory and demo rooms three times in Brixen and twice in Linz, Austria. Polytype (formerly WP Digital and originally Leggett and Platt Digital Technologies) has also moved into developing workflow for digital printing on glass, but it has not yet been possible to visit their new Polytype facilities after they added their focus on glass (I have visited their former facilities twice: Spuhl and WP Digital, but that was before they really focused on printers for architectural glass). The weight of glass is considerably higher than of the normal materials commonly printed in UV printing: 2.5kg/mm/m2. I remember visiting a printshop near Milan, Italy whose manager said how much trouble his circa 2006-vintage NUR Tempo had handling the weight of large glass plates.
So taking into consideration all these aspects: in-line may require the automatic feeding system of glass in the printing machine that is going to increase the production speed tremendously due to the printing process that is continuous and simultaneous with the plates be manually loaded on the feeder in a continuous rhythm. At Glasstec I was shown the designs and plans for a new system of in-line wide-format inkjet printing on glass. I doubt any of the competitors exhibiting at Glasstec were aware of this new system. This will be described in the next TRENDs from the FLAAR Reports (available by Subscription by writing ReaderService@FLAAR.org). Plus five days after Glasstec I learned of an entirely new company that just entered the market. I doubt if any of the wide-format exhibitors at Glasstec were aware of this new competition (neither of these printers is made in China; the printer systems described here are highly sophisticated. In other words, what you saw at Glasstec was only the tip of the iceberg. A brief presentation of one current glass decoration process is to be found in Specialist Printing magazine site: under the Process Information Centre: Printing on flat glass.
For printing on glass, I would estimate that 90% of the UV printer manufacturers claim their machines can print on glass. Just look at their spec sheets and advertising claims. FLAAR does not accept these claims on all their spec sheets. In most cases these claims are misleading at best and inappropriate. The only companies where I have seen experience with printing on glass would be
I would like to point out that the Skyjet (SkyAir Ship) have been selling printers for glass somewhat longer than other companies who may emblazon their ads by saying they were first; I would bet that SkyAir Ship had their specialized glass printer long before). Now, in 2010, other UV printer manufacturers are showing glass versions of their flatbed or combo transport belt printers. I saw these other brands at Glasstec 2010 in Duesseldorf Germany last week. There will be new FLAAR Reports on digital inkjet printing on glass as a result. I am only convinced that a manufacturer can legitimately sell into the glass market when either I see a chemist in their company headquarters who knows glass and or ink chemistry for glass, or when I see a relationship with a major university chemical department or other comparable technology department (WP Digital with the University of Bern); Durst with several universities in Austria). For IP&I my documentation was visiting a printshop that printed on glass year in year out. SkyAir Ship has the experience gained from more than one hundred glass-printing shops that use their earlier models. Merely putting glass samples in your booth is not enough. Merely listing glass in your spec sheet is worse. And I am not impressed by any company that says they don't need a primer. In order to believe that I would need to see significant glass decoration companies daring to sell such a product to a skeptical end-user. If you are using UV-curing inks, glass requires a pre-treatment and in many cases needs post-treatment as well. If your UV ink needs no primer, then you probably need post-treatment, namely firing in a special oven at high temperatures for about 20 minutes. It is not appropriate to sell a printer without the entire workflow machinery. Again, we congratulate WP Digital and GCC for their experience with the complete workflow for printing on slippery surfaces. And I am impressed by the progress made by SkyAir Ship in handling the physical sheets of glass on their printer (glass is heavy, and obviously fragile). I can add additional UV printing companies to the list of reliable resources with realistic factual knowledge of glass decoration when I see their ability in their factory and/or in their headquarters demo room. Another way to protect the glass is to sandwich it between another layer. This way no one can use alcohol, Windex or other cleaning fluids, and no one can scratch it. Just hope that no condensation gets inside from change of temperature over the seasons. But if you laminate your glass then indeed you may not need to heat-treat it after printing or in some cases even prime it before printing. But… what about stacking the glass after it is printed, and between the time it is printed and when it finally gets laminated! How many of the images will be scratched or otherwise marred? If you do not want to print directly on the glass (for many reasons), you can print on PVB or other films and sandwich that between layers of glass. If you use the correct materials the result is triplex safety glass. At APPPEXPO in Shanghai about three or four of the booths were using a UV-curing ink for glass from Toyo (even when they were not actually printing on glass). Unfortunately the color and saturation of this ink is not very attractive (a polite way of saying it is dull and boring). I have seen other glass ink from other brands that is even worse (so dull I don't know why they bother to show such weak samples at a public venue). So if someone promises you an ink that will adhere to glass, be sure that the colors will pop. Otherwise, a dull image on glass is less inspiring than a dull image on PVC. In the meantime, on this FLAAR web page, I will list some glass decoration resources. GlassBuild America is a major show, autumn, includes glass printing UV-cured flatbeds. This event includes glass, windows, and doors (shower doors and all other kinds of doors). Organized by the National Glass Association. Their year 2010 event was in the Las Vegas Convention Center, Sept. 14-16 (Tuesday through Thursday). It alternates between Atlanta and Las Vegas. Glassman Europe, Czech Glass Society. There are also Glassman exhibitions and conferences in other parts of the world. Glassprint 2009, Darmstadt, Germany, 25-26 November 2009. Glasstec 2010, Duesseldorf Germany, 28 September through 1 October. Glasstec 2012 will be in Dueseldorf again. Vitrum 2011, Milano, Italy GLASSPLEX India, 2011, Mumbai Annual ESMA Glass Publication, Europe Architect's Guide to Glass and Metal Decorative Glass (dg) Door & Window Manufacturer Magazine GFF, Journal for Glass, Windows, Façade, Germany Glass Magazine, National Glass Association, USA Specialist Printing (ESMA), Europe Glass Worldwide (ESMA), Europe US Glass Window Film, USA Window&Door, USA Glass Associations (in US; many more in Europe, such as ESMA). American Architectural Manufacturers Association (AAMA) Bath Enclosure Manufacturers Association Glass Association of North America (GANA) Insulating Glass Manufacturers Alliance National Glass Association The major glass artists, architects, interior designers and print shops need ceramic frit inks for longevity. Every giclee atelier and décor printing company complains about UV-cured chemistry today; they state clearly that UV-cured ink is inadequate for when longevity is needed for décor and outdoor architectural decoration. Ceramic frit inks can be jetted through Spectra printheads, but almost no normal printer manufacturer offers this kind of ink system in a regular flatbed printer: because the ink layer on the printed glass then has to be heated in an oven. Printers such as the GlassJet from DIP Tech understandably and appropriately tend to be exhibited at glass expos not signage expos. So most of the technical glass printers are not at FESPA, and actually rarely even at DRUPA 2008.Printshops in strip malls don't have the space (or investment capital) for this kind of system. Printshops in the real world, the mass-market printshops, look for a more realistic way to print on glass for normal projects and normal applications: such as a new museum exhibit, or a store front, or a new office. Thus I was interested in learning about Ormo Print, Ormo Print GmbH, from Bryan Collings (Publishing Director, Specialist Printing, at his booth at VISCOM Duesseldorf 2009). He told me about Prof. Dr.-Ing. Ferdinand Trier, at the Munich University of Applied Sciences (Fachhochschule Muenchen). Professor Trier is at their Laboratory for Measurement Techniques Consultation for Glassing and Glasscoating, Lothstrasse 34, D-80335 München. His e-mail: trier@fhm.edu The ink from Ormo Print is briefly described in Specialist Printing magazine, 2009. This Sol-Gel is a solvent-based ink, not a UV-cured ink. As soon as I have an opportunity to test this ink I can update my observations. In the meantime, the most realistic printers to handle glass remain UV-cured flatbeds. There are plenty of uses for UV-cured ink which will last several years inside and at least a few years outside: not enough for building decoration on a façade facing outside, but adequate for temporary decoration. At Glasstec 2010 in Duesseldorf, Germany, it was possible to chat with Professor Trier in the booth of his technical university. My interest in glass comes from my background in architecture. Half of my family for three generations have been architects: just Google Hellmuth architect and you will see why I studied architecture my first three years at Harvard. 100% of the entries for all initial complete page after page of Google results are all family. But for my junior year I took a year off to do architectural history research on 8 th century Mayan temple pyramid and royal palace architecture of Peten, Guatemala, and I stayed in archaeology for many decades, moving from Harvard through three research positions at Yale. Being an archaeologist meant I spent many years looking at glass: museum exhibit cases! But most museums are too static, a polite way of saying a tad 18 th century. Surely there are ways to make a museum come to life (and I don't mean only at night in the silly way as in the movies that entertain you as you fly on an airplane and need to watch mindless movies to relieve boredom). So printing on glass is because I enjoy all aspects of architectural decoration, I seek better methods to decorate museum glass (exhibit cases), and I am inherently interested in innovative technology per se. Our interests in printing on ceramic tiles, metal, and glass require research, for which reason we appreciate when corporations host our visit to their facilities. Hosting a visit means covering the (economy) airfare, hotel, meals, and local transportation and a modest stipend to help cover our costs in reaching 470,000+ print shop owners, managers, printer operators and other companies and individuals around the world who wish to learn about flatbed printers. As soon as hosted visits and research stipends are available for late 2010 and throughout 2011, we will be updating our FLAAR Reports with additional discussions of printing on glass. Our Hellmuth family background in architecture is a help, as is our decade of experience with UV-cured flatbed printers. Of course today there are additional ink chemistries, which is all the more good reason for new research projects here at FLAAR Reports. As an archaeologist I have an even more natural interest in painting on fired ceramics. Indeed one of my specialties in Mayan archaeology is the iconography of symbolism on painted funerary ceramics, 4 th -9 th centuries AD, Guatemala, Mexico, Belize, and Honduras. I specialize also in the digital photographing recording of these Classic Maya vase paintings (also see www.maya-archaeology.org). For printing on unfired ceramics, Durst provides special printers for this industry. But most needs for decorated ceramics are not from factories, but from artists and architects and graphic designers: they need to print designs on ceramic tiles that are already fired. Here the best company is GCC: they have two separate chemical companies who have created the necessary primers. I hope that in future updates on this page I can add additional printer manufacturers to the list of recommended resources. For GCC I know about their capability since I have visited the chemical companies in Taiwan and China (near Shanghai). There are already FLAAR Reports about these visits. Any company that claims they can print, with UV-cured ink, on fired clay tiles, with no chemical treatment are even less convincing than a company claiming the same unlikely workflow for glass. Anyone can print on glass and on tiles: the question is whether it will fall off after a few months, especially if subjected to heat. The tiles we printed at Gandinnovations factory were put on top of our microwave oven and the entire layer of ink puckered up and came off completely ( meaning that 100% of the ink layer came off). I thank Diana Dogaru of WP Digital (now Polytype) for providing helpful, current, and useful information on glass conferences and glass symposiums. She has considerable real-world experience in UV-curable printing on glass (as well as color management and other aspects of grand format printing, both traditional solvent and the latest UV-cured). I thank the management of SkyAir Ship for arranging that the FLAAR Technical Writer on UV-curing printers (Jose Melgar) and myself could spend several days visiting their factory and demo room in China two years ago and again a second time during October 2010. Sky Air Ship is the #1 seller of UV-curable flatbed printers inside China. Most of their printers are used for decorating glass. Their glass industry partner in America, IGE Solutions, exhibited their flatbed printer at the major glass decoration trade show in Atlanta. Mark Ma from Sky AirShip was there. I thank John Vu, TMP Glass Style Corp, (Thien Minh Printing, and Thien Minh Design Fine Art) Ho Chi Minh City, Vietnam, for providing hospitality while inspecting his extensive glass working and glass printing facilities in Vietnam during 2009.
Most recently updated October 4, 2010, after attending Glasstec 2010 expo in Duesseldorf, Germany. First posted October 21, 2009. |
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