Ceramics Technology & Design - March 2011
By Darius Helm & Jessica Chevalier
The last decade has seen an explosion in ceramic tile design, with ultra-realistic faux looks, incredible textures and a range of abstract visuals entirely new to the flooring industry. Some of these new designs are driven by technological developments, while others derive from the progressive visions of the designers themselves.
One of the more noteworthy developments in ceramic tile surface technologies is digital inkjet printing. The first machines came out in 2000 at Cevisama, Spain’s giant tile show, and over this last decade the technology has evolved to the point where the newest machines now use a palette of up to six inks to create image resolutions as high as 1,000 dpi. Digital inkjet technology, while still developing, is already by far the best tool for precision tile visuals. All the big manufacturers have invested in the technology, and it won’t be long before all but the niche producers have it as part of their design arsenal.
Beyond the surface of the tile, there are two other significant tile trends, both originating in Europe and gradually gaining acceptance in North America: large formats and thin tiles. The design community, which is always looking for fewer seams in its products, has been particularly drawn to large format tiles; the reduced grout lines offer a richer aesthetic. Formats have been increasing for several years, and U.S. producers have embraced the trend. Crossville, for instance, can make tiles up to 24”x36”, Florim USA stocks tiles as large as 24”x24”, as does Fiandre’s StonePeak, and Marazzi has a 24”x48”. Manufacturers can go bigger too, but it’s also a learning curve for installers to get used to handling the large slabs and using new setting materials. And in the U.S. market, at least for now, there’s not much demand for formats much larger than what’s available.
Thin tiles, pioneered in Italy, have been around for about three years. While standard tile ranges in thickness between 9mm and 11mm, some of the newer tiles on the market come as thin as 3mm, or 4mm for glazed products. The market’s first reaction was to be wary, understandably; it’s hard to believe that a piece of tile only 3mm thick, which is less than 1/8”, can withstand any kind of sustained pounding. And even now there’s a perception among many in the flooring industry that those thin tiles are really designed for walls.
However, thin tile is gaining traction in Europe, where it’s installed over existing floors that can accommodate the slight increase in height or over level subfloors. And, if of good quality and installed correctly, the thin tiles appear to live up to their reputation of strength, resilience and, surprisingly, flexibility. Some thin tiles feature performance enhancements, like Cotto D’Este’s Kerlite Plus, which has a 0.5mm fiberglass backing for added impact resistance. Thin tiles are now making headway in the North American market, though, much like large format tiles, installers are having to learn new techniques for how to handle them.
In terms of U.S. producers, StonePeak sells 4.5mm thin tiles from Italian parent company, Fiandre, in the North American market, and American Marazzi also offers a thin tile, 4mm, made by Marazzi in Italy. Daltile is currently importing a 12”x24” thin tile, while Florida Tile’s parent, Panaria, was one of the first thin tile manufacturers, and in addition to 3mm tile the firm offers enhanced strength and rigidity for flooring applications through a laminated product of two 3mm slices sandwiching a fiberglass mesh, for a total thickness of 7mm.
There are, loosely speaking, two types of tile constructions: through-body and glazed white-body. A through-body tile, which is unglazed, infuses color in wet-milled granules, so the color goes through the whole tile, and the surface, be it polished, matte or textured, is the same color as the body of the tile. Glazed white-body tile derives its visuals largely from the glaze. Through-body tile goes to the commercial market, while glazed white-body goes to both the residential and commercial markets.
Tile with a through-body construction is designed for performance, often in heavy commercial settings like airports, where it has to sustain all kinds of indignities. The through-body construction is ideal for hiding scratches and chips. However, designs tend to be more limited; it’s at its best with stone looks, where salts and atomized clays can be used to create veining, shading and color shifts. Crossville’s Buenos Aires Mood, for instance, is a through-body with a lush, convincing stone look.
Through-body tile is generally a higher end product, and it gets even higher as more pigments and materials are added into the body. One method manufacturers have developed to offer those high end through-body looks at more affordable prices is by double loading, in which the lower two-thirds of the tile is made of pure technical porcelain and the upper third features all the bells and whistles, and the combination is then pressed. That 3mm layer can both offer high design and accommodate all the pounding of a high traffic installation.
Double pressing is another technique, in which the first layer is pressed, the decorative layer is added, and the tile is pressed again. In double pressing, the top layer is thinner than in double loading.
StonePeak, a Tennessee manufacturer, uses the patented technology of its parent company, Fiandre, for enhanced through-body styling. A huge structure that hangs above the press enables powders to be delivered in multiple ways, both enhancing design options and streamlining the process.
Another type of tile gaining in popularity is color-body, a glazed product with particles in the tile body coated in color as opposed to infused—which means that polishing would reveal the white color of the particles, so the procedure is to glaze the surface the same color as the body. It’s not as abrasion resistant as through-body and it can’t handle heavy traffic areas like airports where through-body is often specified, but its color-body construction still appeals to specifiers for a range of high performance commercial installations.
Tile and Texture
The basic procedure for making tile is to press it, glaze it and fire it. As the tile travels down the line, a pair of steel punches, one on the top and one on the bottom, press texture into the tile; one creates the standard profile of the back of the tile and the other creates the texture on the top—the profile of the tile, as opposed to the literal texture (whether it feels smooth or rough, whether it’s slip resistant) and gloss level, which is determined by the glaze.
The use of texture, and the variety, has exploded in recent years. Microtextures and small scale faceting have been used to achieve stunning visual effects; textured stone looks, like slate, have become much more dimensional; and new wood designs feature precision graining that’s indistinguishable from the real thing. However, in many ways these developments are design driven, not technology driven. The steel punch is much the same as it has been for years, and techniques for creating greater precision have steadily developed as design has evolved.
The most dramatic advancements in texture have come from glazed tiles, and new glazing technologies that enhance the aesthetic function of texture—most notably, digital inkjet technology.
Tile Glaze Developments
Dry glazing, which is used in through-color as well as glazed tile, involves the use of powders that are deposited on the surface of the tile, and it’s often applied to create veining and other characteristics of natural stone. Wet glazing, which is applied in standard glazed tile, uses a suspension of water, minerals and frits, which are essentially finely ground glass. The glaze is applied, traditionally through a roto-color cylinder, and when the tile is baked, the glaze fuses to the tile. Colors are achieved through the oxidation of the minerals in the baking process—oxidized cobalt is blue, oxidized iron is rust, etc. Dry frits added after glazing can be used to create overall surface textures, from high gloss to ADA compliant slip resistant finishes.
Competing with the roto-color process is the latest wet glaze technology, digital inkjet printing.. All the major U.S. tile firms have now invested in digital technology, which works very much like an inkjet printer in a home office. Ink is sprayed out of cartridges onto a tile that is passing below. Just like with a home printer, the pattern is controlled by a computer program.
This technology has gained popularity in part because of its ability to create visuals that emulate natural stone, especially stone with multi-layered, detailed signatures, like limestone, travertine and marble. Through digital printing, ceramic tile design has become virtually unlimited—it’s whatever a designer can dream up. It’s also more customizable than ever, though that’s usually a cost-prohibitive endeavor.
However, the medium does have limitations, the most significant of which is a somewhat constrained color palette. Traditionally, colors like true black and true magenta have been hardest to attain in ceramic tile, but with digital printing, which uses different mineral solutions, white has been the most elusive.
Digital printing is largely based on the standard four-color CMYK palette, with limitations, but over the last couple of years there has been a lot of progress. For instance, Spain’s Inalco was one of the first to add a white cartridge, and American Marazzi recently upgraded from its yellow, black, blue and brown palette with the installation of a new machine that adds two additional color cartridges, white and magenta, vastly expanding the range of colors that can be achieved.
Another potential limitation is that, if manufacturers choose to print their images at a high dpi to achieve a richer look, digital printing runs more slowly, just as a desktop printer slows when it prints in photographic quality. Printing at a higher dpi also uses more ink. Both of these factors impact the price of the finished product, since output dictates the cost of production.
Currently, there are seven or eight digital technology suppliers in the market, and each of the machines offered by these suppliers has strengths and weaknesses, depending on which effects the manufacturer is trying to achieve. As with any other technology, the quality of the product is also dependent on the ability and experience level of the operator running the machine.
Roto-color is a much different, more mechanical technology, and it is, for now, still the standard and traditional way that tile gets its visual appearance. A laser cuts a design onto a silicone drum; then the drum is coated with a ceramic printing paste, and a tile is rolled underneath it. One tile is printed consecutive times with different colors and designs, like silk screening, to create a full image. For instance, a grey under layer might be applied first, with a black veining applied next and white highlights atop that. This method demands that the machinery be perfectly synchronized and aligned so that the tile images do not appear blurry. Roto-color images generally use five or six colors, though they may feature up to ten. When printing a roto-color image, some of the rollers can be made to lift randomly to create shade variations.
It wasn’t long ago that roto-color technology was state-of-the-art, and the equipment is pretty sophisticated. For instance, in creating a faux stone look, the image of a real stone is scanned into a computer program, and the program then separates the image into RGB colors. The three images, one for each color, are then printed onto the silicon roto-color cylinders with micro-holes through which the colored glaze passes to coat the roller and in turn transfer the image onto the tile itself. Florida Tile employs an advanced eight-color roto-color machine that can do anything from monochromatic looks to intricate veining.
Rotor-color technology can also be synchronized with the texture from the punch to create in-register looks, but it has always been an imperfect union.
Inkjet: The Great Uniter
The perennial fail of roto-color has always been its ability to print on textured tile. As a drum rolls over a tile, it misses the low spots of the textural design created by the punch during the pressing of a tile. Any groove, etching, nook or cranny of more than a vertical half millimeter can’t be reached by the roto-color glazes.
Traditionally, this has meant that any product with significant surface texture from the punch could not handle more than a solid color glaze, or at best a multicolored glaze designed specifically to finesse the shortcomings of the application on the textured surface. Or, conversely, a complex glaze design could only be applied onto a flat surface.
According to Ryan Fasan of Professional Attention to Tile Installation, inkjet technologies have bridged the gap between texture and glaze design, enabling the creation of complex glaze patterns on top of textured surfaces, because the inkjet sprays the glaze, saturating every pore.
With digital printing technology, the texture from the punch can be colored in-register, thoroughly and with great precision, enabling the creation of faux wood and stone looks that survive even the closest scrutiny. It’s great for the industry, because it positions tile to take new share from the stone market in both commercial and residential applications.
Digital printing is so precise that it can also be used to enhance the dimensionality conveyed by the punch, by using shading and color shifts to accentuate the depth of the relief or to highlight contours.
Most tile manufacturers agree that the future of tile design is in combining all the technologies to take tile to a new level, using textures, dry glazes and digital printing in coordination. This will become more obvious a couple of years from now, when high-volume, low-cost producers, like many of the Chinese manufacturers, invest in inkjet technology and start spitting out precision stone and wood looks on tile as flat as a mirror.
Daltile, for instance, has been focusing on developing support technologies for digital printing, and recently invested in image capturing technology that can take images from natural stone, scan them into a computer program and generate high-definition graphics. And Italian producers are already experimenting with using digital printing in combination with double loading.
While printing technologies are continually improving the picture on the tile, the translucency of stone is more difficult to replicate. But manufacturers don’t think this will be the case for long. According to American Marazzi’s executive VP of sales and marketing, Hector Narvaez, it can be difficult to reach the same gloss levels without using a marble polishing machine, whose diamond heads will tear up tile. However, thicker, stronger glazes can be polished down more, and he expects that in the next three years this process will be able to be completed in a cost effective manner, and marble look tile with realistic-looking gloss will be available for purchase.
However, real translucency requires manipulating more than just the surface of the tile, and that can be achieved, to some degree, with double loading. Sean Cilona, Florida Tile’s director of marketing, explains that the top layer in double loading can be made to be more translucent, and may include specks to show depth on the surface, especially when polished.
Metallic look tiles have become much more prevalent over the last five years, and the looks are achieved by applying crystallized metals—like iron—to the tile before firing. Manufacturers use a variety of techniques to achieve metallic looks. Some mix metals into a liquid glaze, then apply the glaze to the tile through the use of rollers. Flash brushing below or atop printing is used to create a subtle look. To achieve a veined appearance, manufactures apply the metals using roto-color technology, and, to create an entire metallic surface, they use a waterfall process with lots of metal flakes.
Another popular look is fabric effects, and these can be achieved in the punch or with the application of micronized powders during the pressing stage. Even the glazing from inkjets can be used to create textures on the surface. And again, the more techniques that are used, the more convincing is the final product.
Copyright 2011 Floor Focus