Glass tiles owe much of their current favor to modern recycling technology, which transform discarded windshields, beer and beverage bottles into “green tiles.” Computer-aided design, and laser-cutting technology have now provided the precision that handcrafted tiles could never attain. Advances in anti-slip coatings have eliminated fears of slippage while walking on glass.
Once the exclusive realm of only the most accomplished interior designers, glass tiles have gradually become a mass-market option that go beyond most basic modern kitchen and bathroom designs. Glass tiles have been used in columns, backsplashes, fireplaces and cooking alcoves. They are durable, tough, non-porous and resistant to fire, water and liquids. Glass is environmentally friendly, easy to clean and does not retain bacteria, mold and mildew.
Aesthetically, glass tiles are visually arresting. The depth and natural transparency of the tiles reflect, rather than absorb light. This creates the effect of an internal light source, an illusion of being perpetually backlit
Their translucent colors, iridescence and compatibility with other materials such as ceramic and porcelain reflect the artisans’ personal touch in each construction. For handcrafted tile, each is unique, imbued with its craftsman’s passion and character. Smooth, seamless polychromatic glass tiles now match diverse materials. Striped or checkered tiles, for example, now feature glass chip mosaics and geometric motifs.
Glass tile owes its genesis to the mosaic art tiles that were present around 2,500 BC. Glass pieces were incorporated into mosaic tiles for contrast and special effect. Greek and Persian artisans were already practicing a flourishing trade creating exotic mosaic art on manufactured tiles. Tiles became a physical symbol of how artistic expression and commerce coexisted harmoniously in the ancient world. As mosaics developed into more complex designs, the new art form demanded new materials from artisans.
When Constantinople became the imperial center of the Roman Empire in 330, artisans incorporated glass bits to stone and ceramic tiles to add detail to religious themed artwork. The 5th century A.D. saw the Byzantine Empire (the Roman Empire’s eastern portion) become a center of glass tile mosaics. Skilled artisans created textured and opaque glass tiles for temple walls and ceilings and then, stained glass windows.
Stained glass and glass mosaics entered the American consciousness with the Art Nouveau movement at the turn of the 20th century. Glassmaker and painter Louis Comfort Tiffany, scion of the famed jewelry company Tiffany & Co., experimented with opalescent glass to create a distinct colored glass panels and pieces. He patented the Favrile iridescent art glass and used it to produce blown glass vases and lamps. These lamps and vases were a huge success in the 1960s and helped broaden the acceptance of colored glass fixtures into the home.
If clay is used in ceramic tiles, silica is the basic raw material in producing glass. Carbonates and metal oxides such as copper or cobalt are added to stabilize and color the molten mixture. This pasty, viscous batch is fired in an oven or furnace and formed into slabs for cooling. The slabs or patties are then cut into the desired shape and size. To create a uniform size the smelted paste is placed into capsule-shaped molds rather than rolled out and cut.
Modern glass tiles are as strong and as conventional tiles. Cold-manufactured glass does not use heat. It involves the mechanical process of cutting the glass into specific shapes. Other processes are melting, casting and cooling the glass. Whatever the process involved, they are usually classified as Smalti, fused, sintered, and cast.
Smalti is an Italian word for glaze. Smalti was created during the Byzantine Empire in the 5th century to complement marble and granite tile colors. The surface of Smalti tiles is coated with silica, metals and potassium carbonate for a gritty texture. Copper oxides are responsible for the cloudy color effects and layered swirls. The molten mixture is placed into slabs, fired, cooled and cut into individual tiles, or tessarae.
Smalti glass is available in variations of gold, metallic and translucent. Sandwiching a gold leaf between a brown glass veneer and the main Smalti slab produces gold Smalti. For metallic Smalti, copper is mixed into the molten glass then pressed. The effect is marbled copper streaks on the glass tile. Miniature, uniform colored stained glass tiles is the best description of translucent Smalti. Colors are kept light to give a luminous depth to the tile.
Fused tiles are also translucent. They are formed when float glass (ordinary window glass) is cut, fired and fused with color. They are subsequently etched and coated for added protection against abrasions. Pressing and heating glass power until the particles fuse produce sintered tiles.
Cast tiles give a more layered look, especially when marble shavings, sand or Portland cement are added to the mixing process. They are placed into a mold together with glass chunks. The whole mixture is heated until all the elements become a congealed mass. The cooled tile is an amalgamation produces a rich, textured surface.
To create curves, glass plates are melted and poured into relief molds. Upon cooling, the contours solidify to yield what is called “slumped tile.”
Production methods affect tile texture. Fused tiles are flat and have a smooth finish. Cast tiles have a more rippled and reflective texture. Sometimes random surface variations give a glass tile a mottled look. Tiny bubbles give a wet-look.
Like other tiles in the market, glass tiles are available in standard geometric shapes or can be custom made to different sizes, shapes and textures. Mosaics generally incorporate irregular shapes and patterns. Standard square tiles are 1”x 1” or 2”x 2.” Medium tiles are 4 ‘ and 5” squares and large size tiles are 6 to 8” cuts. The rule of thumb is that large cut tiles are for large rooms and smaller tiles are for small rooms.
Surface finishing on a glass tile enhances the appearance but can also reveal scratches and cracks. This is true for a glossy finish. An etched finish subdues the inherent reflectivity of the glass into a more subtle opaqueness while a metallic glaze finish creates a shimmering, prismatic exterior.
Installing glass tile employs the same rudiments as ceramic and porcelain tile installation. Substrate surfaces must be clean, leveled, stable and free of stains and dirt particles. In other words, since glass is translucent, the subsurface must be clear, smooth and perfect. Cement or cement board are ideal substrates. A crack suppression membrane is placed between the substrate and the glass tile to protect them from movements below. Once the tiles are cut, they are pressed with a mixture either sand, cement, acrylic or latex polymers to eliminate air pockets and help adhere to the backing. When it comes to grouting, sanded grouts are not recommended because they will scratch the tile surface. Epoxy grouts are viable because they naturally adhere to glass, are strong and last a long time. Set time for grouts is about 24 hours and should only be cleaned of any lingering film a day after installation.
It has taken over 2,500 years for glass tiles to achieve a comfortable place in the American home. Modern technology and the dedication of passionate artisans have kept this decorative art from remaining in the fringes of the privileged few. With unlimited creativity, glass tiles can serve as accents alongside more traditional tiles. Yet, it can also stand on its own as an integral part of the modern home interior.