Formally limited to only small sizes in several types, glass tiles have grown into a dazzling array of numerous types and some very large formats. The design possibilities seem endless with the technology advances that have occurred.

This bathroom shows the dramatic effect of using mix media. Glass more than any other tile product requires the patience of an artist. Photo courtesy Bergerson Tile.

I gave quite a bit of thought to titling this article. For me it is the title that sets the tone of what and how I write. When it comes to glass tile, many thoughts float through my mind, mostly good thoughts, of this increasingly popular product. On the evolution side, glass tile as a material has been used in various decorative and floor applications for thousands of years.

Formally limited to only small sizes in several types, it has grown into a dazzling array of numerous types and some very large formats. The design possibilities seem endless with the technology advances that have occurred. That is the evolution of the product. But there is also a revolution of sorts. These small and decorative glass tiles were formally available only to royalty and the very rich.  Only the best craftsmen served these ultimately discriminating customers using the primitive installation material and method of sand and cement.

As the penalty for failure could be death or incarceration, one can imagine poorly performing installations were very rare to say the least. Many of these installations exist today and more are being discovered all the time. The old mud method of installation has millennia of proven history with small size tile. Many modern day tile setters revolt at the sound of mortar work. Indeed, while writing this article, I had a call asking if “they still did that anymore.” Properly done mortar work by skilled tradesman today remains the Cadillac of installation systems and no knowledgeable professional will argue otherwise.

Now, back to current events. Modern technology has provided us with many new manufacturing processes. While glass tile and other mosaic tile has been paper face mounted for many years, other alternatives have joined the ranks. We now have film-mounted, dot-mounted, paper-mounted, not to mention, plastic mesh-mounted. With glass tile itself, we have laminated, cast, fused, and sintered with many variations of each process. Perhaps the most modern feature is attached backings to glass tile that provide endless design possibilities and are at the same time less critical of perfect thinset applications and curing issues.

Each type of product and variation provides infinite design potential and posses its own specific installation requirements for performance. It is not completely unreasonable (a stretch perhaps) to say tile is tile when it comes to clay tile products coming out of a kiln. It is however completely unreasonable to say glass is glass. Each type of glass tile and mosaic product along, with its mounting if applicable, has its own specific needs. Large glass tile raises some additional concerns. In this article we will share some very basic and universal principles for glass tile installation.

One of the secrets of success with glass tile is white thinset with and full coverage. It is very important that all glass tile, large or small, be fully embedded and supported by thinset. In translucent or opaque glass it becomes critical. Photo courtesy MAPEI Corp.

Anything is only as good as the surface it is installed over. I could easily extrapolate that item into a separate article but perhaps another time. For strictly decorative applications, such as a backsplash, most glass tile can be installed over nearly any surface free of contaminates to which a reasonable bond can be achieved. If areas require more performance such as a floor or wet area, a cement-based substrate is preferred for stability and other reasons we shall explore. These substrates also need to be “true,” that is to say flat and in some cases square. A common practice in tile setting is to add a little thinset here and take away a little there to make things lay flat. This does not work on glass tile. All bonding products shrink as they dry. If one side of glass tile is pulled greater than the other side by the drying process, then cracking may occur, particularly in larger size glass tile (those over 3"x 3").

The waves in this picture show the curing process of thinset that shrinks as it dries. Always get a specific recommendation for setting materials from the glass tile manufacturer.

Another area of mixed recommendations is installing tile over membrane systems. The easy part of explaining the mixed recommendations is the membrane itself. As with stone, not all membranes are suitable for glass tile. Some are overly compressive and may work fine under an 8"x 8" ceramic but will not perform under glass tile. Another issue in some cases is curing time, both the initial and final drying time. Without question, sandwiching a membrane of any type with modified thinset under glass tile is going to cause an extended cure cycle. Under translucent or opaque glass it can also cause “picture framing” as the thinset is slowly allowed to dry. With larger tile, this can be the cause of months of concern by a customer who may or may not have paid for their project.

For those reasons and many others, prudent glass tile manufacturers have very specific recommendations for installation materials and methods. What works with a backed glass tile may not work with a translucent glass tile. Even among backed and translucent tiles, recommendations may vary due to the manufacturing process.

Cutting glass effectively often requires diamond blades designed for glass tile. In many instances even with glass tile backings, a quality score and snap cutter can be used.

Having been personally involved in the glass standards development process and fielding technical calls on a national basis as an installer, I would be adamant about receiving a set of very specific guidelines for each glass tile product I was selling or installing. If those written guidelines were not available, then I would suggest you align with a manufacturer who has made the investment in research to provide those guidelines. This may sound a little dramatic but let me add some perspective.

At a previous technical meeting, I was seated roundtable with some setting material manufactures. As the setting material representative told the story, a glass tile importer had approached him and asked for some proprietary bonding material recommendations they could make a part of their guidelines. The setting materials company proceeded to perform bonding tests with every product at their disposal including epoxies but could not achieve an adequate bond due to failure at the backing on the glass. They duly informed the glass representative who then went to another manufacture with the same request. Long story short: he had been to all four manufacturers seated at the table and none had a product that could achieve satisfactory bond. The saddest part is this product in is still in wide distribution today. Get a written recommendation!

Part of every installation process with every building material known to man is the use of movement accommodation joints. There is no area of greater need to follow these guidelines than with glass tile that can be highly expansive. Before a single tile is set, and starting with the sales process, movement accommodation should be addressed. This is a very tough sell to an end user that both the sales personal and installers alike wish to avoid.

Throughout my career, it was always a battle to tell someone you needed to put a profile or caulk joint someplace in their normal tile work. Glass tile has a much higher degree of expansion and contraction than normal ceramic tile. Joints to accommodate this are a requirement for each and every tile installation to be successful. These joints can be very disturbing to the end user if they are not aware and educated of the necessity. On more than a few occasions, I have been accused of trying to destroy the “dream” or “ambiance” sought after when I arrived on the job and wanted to run a movement joint in the project. Please educate yourself in this area, which is critical to performance. There are many areas an installer can deal with on the job - destroying the dream sold to the customer is not one of them. If the educated customer elects to ignore the need and roll the dice so to speak, so be it. You may want it in writing or make note of it for a later day that may or may not occur.

Glass tile is no longer a product of the very rich. It is both desirable and readily available across the economic spectrum. Working with glass requires a special understanding of the product and installation needs. Many manufacturers offer specialized training in this area. We hope we see many more of you taking advantage of this highly profitable industry segment by participating in those educational offerings.