Photo purchased from … www.depositphotos.com
Printing on glass is a challenge. After all, the substrate is completely non-porous. In contrast, most commercial printing paper (with the exception of such synthetic stocks as Yupo) is porous. Printing ink seeps in and attaches to the paper fibers, and the vehicle (liquid part of the ink) is absorbed into both the paper and the atmosphere during the drying process.
Not so with glass. The ink sits up on the surface as it dries. What this means is that it will not adhere as well as ink adheres to paper. You can scratch it or rub it off. This means the divider window your architect just installed in your office suite may not wear as well or for as long as you would like, given what you just paid for it.
UV inks are an option. They are cured instantly by exposure to ultraviolet light and will dry right on the surface of glass, wood, metal, or practically anything else. But you still have issues with rub resistance of the ink (and, actually, degradation from light as well).
Of late, however, printers, ink companies, and ceramics professionals are rolling out frit-based ceramic inks that can be printed on glass. Once fired (just like ceramics that have been glazed are fired), the frit-based ceramic inks become part of the glass. (They are no longer just on its surface.) And as with ceramic art pieces, this ensures the durability of the pigment.
What Is Frit
First of all, what it frit? This is what Wikipedia has to say:
“A frit is a ceramic composition that has been fused, quenched, and granulated. Frits form an important part of the batches used in compounding enamels and ceramic glazes.
“According to the OED, the origin of the word “frit” dates back to 1662 and is “a calcinated mixture of sand and fluxes ready to be melted in a crucible to make glass.” Nowadays, the unheated raw materials of glass making are more commonly called “glass batch.”
“In antiquity, frit could be crushed to make pigments or shaped to create objects. It may also have served as an intermediate material in the manufacture of raw glass.”
New Process for Printing on Glass
I found an interesting article on this subject this week, entitled “Digitally Printing Glass for Buildings,” by Ben Pilkington, and published on www.azobuild.com on March 25, 2022. It describes how frit-based ceramic ink can be inkjetted onto glass, which can then actually be fired directly on the flatbed printer (presumably in an oven covering the flat bed of the inkjet equipment). This new technique puts custom printing on glass a step ahead of prior custom printing techniques (screen printing and UV digital printing). As noted before, just drying (or UV curing) the pigment on the glass does not address the problem of ink rub resistance (which also presents as deterioration over time when exposed to sunlight), and even screen printing ink onto glass (a process with considerably more complex and time-consuming makeready than UV digital printing) only ensures ink durability if the glass is fired (after printing and before use).
Moreover, according to the article, these imaging processes can weaken the glass, making them less desirable for printing large panes of exterior glass.
Also, custom screen printing usually requires multiple screens for printing complex, multi-colored images.
So the overall process, whether achieved with custom screen printing or UV digital printing, can take a long time, cost a lot, and reduce the longevity of the glass. Hence, the advent of inkjet equipment that can image highly detailed work (all colors and layers at one time), that requires minimal makeready, and that provides a durable product is a most encouraging development.
“Digitally Printing Glass for Buildings,” does mention an additional process, which can be done with intense heat. The glass must be heated and smoothed, which drives out air bubbles, “voids, and cavities” (“Digitally Printing Glass for Buildings”) and strengthens the glass surface, “ensuring a compacted, strong glass structure” (“Digitally Printing Glass for Buildings”), while chemically bonding the ceramic ink to the glass. After these preparation and custom printing processes, any additional surface coatings can be added.
Why Is This Important?
So now you can print incredible detail on glass at high resolution with an inkjet process that yields a durable product. Why is this important?
First, there are aesthetic reasons. An elegant, printed-glass product can add to the upscale ambiance of a corporate office, burnishing the company brand, all without additional maintenance costs. And since using frit-based ceramic inks actually bonds the ink to the glass, this aesthetic addition will last a long time.
Then there’s privacy. A window between offices can be of aesthetic benefit, but by adding a tint or pattern, the glass can become somewhat less translucent, providing separation between the activities in one room and those in the other.
But the third and most intriguing reason (to me, and apparently to Ben Pilkington in “Digitally Printing Glass for Buildings”) is the environmental benefit. By adding tints to glass, an architect can affect the efficiency of lighting and heating/cooling the building. Depending on the choice of coatings, the ambient temperature in the building can be naturally controlled. And this saves money.
Intelligently designed and placed printed glass can also reduce the need for and cost of interior lighting, depending on the “diffusion or transmission” of the glass coatings (“Digitally Printing Glass for Buildings”). Moreover, these glass panels can even be set at various angles both for aesthetic effect and to enhance their heating or cooling properties.
Finally, “Digitally Printing Glass for Buildings” notes that these ceramic, frit-based inks can be used to add traction to floors, which can minimize falls. They can also be used to mark windows with imagery that will deter birds from flying into the glass.
So between the aesthetic uses and functional uses, this technology has room to run, especially since the entire process benefits from the high-detail, high-resolution capabilities (and minimal makeready) of digital commercial printing, as well as the ability of the glass to control ambient light and temperature in sustainable ways that save money.
This is one trend I plan to keep abreast of.
The Takeaway
Most of you probably won’t be designing imagery for custom printing on glass. Granted. Nor will I. However, it is interesting to note that digital commercial printing, and specifically inkjet printing, is the vehicle for this advance in glass printing. I think that over time more and more processes for creating both objects (3D printing, which is akin to an inkjet process) and print media will depend on this technology of laying down one pass after another of either plastic 3D filament or commercial printing ink (or in this case heat-tolerant, frit-based ceramic ink).
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on Sunday, June 19th, 2022 at 10:01 pm and is filed under GlassPrinting.
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