Estudio Group is a product training and representation team headed by a duo made up of two of my oldest and most trusted tile pals. Fred Jackson, or Fredish as we call him, is the leader of this pack and he is valiantly supported by one of the classiest ladies in our industry- Tracy West. Together they support a myriad of products and train architects, designers and showrooms around the US. Rarely will you come across more knowledgeable tile experts.
Today- I'm sharing some words of wisdom written by Tracy regarding glass tiles, in general, and installations- specifically. I'm hoping to bring more sage advice from these industry experts in the future.
Tech Talk: Glass Tile
By Tracy West, Estudio Group Western Regional Manager. West has over 30 years building industry experience. Estudio Group is a sales, training, and consulting company specializing in natural stone, ceramic tile, and green building industry products and may be reached at 714.813.6598 or www.estudiogroup.net.
As I talk to folks in the tile industry, the one complaint that I hear over and over again is the problems that arise in glass tile installations. There has been so much frustration for industry professionals that they refuse to spec or use glass tiles any longer. I used to be comfortable blaming low quality glass, and we all know that there is plenty of that on the market; however, further investigation showed me that even the high quality glass products could be problematic.
This Tech Talk article will talk about glass tile, how it is made, and the best ways to install glass tiles and some of the innovations in that area. It is not magic; it is really about knowing the product, having reasonable expectations for the product, and knowing how to use glass tile in an installation.
TYPES OF GLASS TILES
Let's start with a brief rundown of how glass tiles can be made, and get our glossary of terms straight:
- FUSED GLASS can be made either in a "COLD FUSED" process where paint or metal foils are applied to the back of the glass tile (cut from a sheet) and it is low-fired to adhere the decorative elements to the glass. Since the decoration is lightly adhered, these tiles require careful handling. They vary greatly in price depending on the type of glass and decoration, but hover in the upper-end.
- FUSED GLASS can also be made in a high fire method or "WARM FUSED" process where layers of sheet glass with color, metallics and decorative features are "fused" together in a kiln at a higher temperature than the process above. This makes a more durable tile since the decoration is imbedded in the glass. These products are mostly higher-end as well since the high firing can add expense in manufacturing.
- CAST or POURED GLASS TILES are made with the silica in a molten state. The color is integrated into the glass, and the molten material is poured into sheets or cast into molds. The critical factors in this method are the temperature to which the molten glass is heated, how long it is kept at that temperature, and the time that is allowed for the glass to cool...this is called "tempering". Holding the temperature of the molten glass too high or for too long a period of time or tempering it too quickly can make the glass brittle so that it can crack or chip easily during shipping, or during or after installation. Unfortunately, you cannot tell about this kind of a flaw by looking at it. It requires testing. Pay attention to price with these products since it can be a good guideline. In this group of tiles you "get what you pay for" more or less.
- SMALTI are the small (classically Italian) tiles made from a silica-based paste with metal oxides added for the intense, saturated colors that we associate with them. They are often paper face-mounted and sold in sheets. After many years of being neglected, these tiles are very popular again. Because of the high level of (often very expensive) pigments in the silica, these tend to be on the very pricey side.
- SLUMPED GLASS is made by taking pane glass, which can be decorative and colored, and putting it in a kiln at a high enough temperature so that it will melt over a casting mold to take a shape. This method is often used for shaping bowls and vessels as well as some sculptural, "art glass" decoratives. Again, expect wide price ranges here depending on the glass used, size and end product. Remember the cost of careful tempering, because tempering is really important here.
The field tiles that most of us see in the showrooms are poured glass that is either poured into molds that are the shape of the finished tiles or into sheets that are cut into the tile sizes after tempering. The least expensive tile tend to be poured into molds since there is much less labor involved in this method. When the tiles are poured into sheets and cut, there is a lot of handwork involved...and a finer look as well. In both cases, the glass tiles are finished with grinding to get rid of sharp edges, and perhaps polished to finish them off. Chemical treatments are used to create the "frosted" glass or some of the other special affects that we are seeing now.
GLASS TILE INSTALLATION
BEST PRACTICES in installing glass tiles. My friend and fellow tile contractor Doty Riley said something to me once that I want to pass on to you: "Just because a person is knowledgeable about setting ceramic tile, that doesn't mean they know anything about setting glass!" This statement gives us Rule #1: Setting glass is not the same as setting ceramic tile!
Why not? Maybe the most important thing to know is that glass has an amazing ability to expand and contract in reacting to temperature and temperature variations. This along with its other wide ranging properties make it very different from ceramics, and require that it be set on extremely stable substrates with specifically recommended setting materials.
Glass is also impervious, so it has a very low rate of absorption. It can also be brittle, heavy and have a slippery back all of which make it unforgiving in the kinds of setting materials that can be used with it. The setting materials HAVE to be compatible with the glass and with the grout and substrate materials as well. This is true of tile and stone too, of course, but it is truth on steroids with glass.
- SUBSTRATES: Glass can be set on walls or floors (only when recommended by the manufacturer), on cured mortar (ANSI A108.1B), CBUs (ANSI A118.9), properly cured concrete slabs, and gypsum board (in dry areas only). It is NOT recommended to install glass over wood substrates.
- SETTING METHODS: There are many setting materials coming out that are specifically formulated for glass, but two "conventional" setting methods are recommended as well: installing a Crack Isolation Membrane under the glass tiles, and using modified thin-set with additional latex add mix as the bonding agent. (These two methods can be used together as well for added security.)
- CRACK ISOLATION MEMBRANES are polyvinyl chloride (PVC), polyethylene, or chlorinated polyethylene (CPE) sheeting that is adhered to the prepared substrate with a bonding agent. Then the glass tiles are adhered to the sheeting with another layer of thin-set. The sheeting usually has imbedded poly fibers on both sides thatallow the substrate, the sheeting and the glass tiles to move at different rates while maintaining a strong bond between them. (The characteristic of allowing this slip sheet kind of movement is called "elongation", and different membranes allow for different rates of elongation, so check with the manufacturer on that.) It is CRITICALLY important that the bonding agents and the membrane be compatible. For example, PVC membranes do not like latex modified thin-sets, and you cannot use them together. Refer to ANSI A118.12 for the specifications on this method.
- LATEX MODIFIED THIN-SET is readily available with the latex modifier pre-mixed in the dry thin-set. For a secure glass tile installation, rather than water as the wetting agent, however, a latex add-mix can be used. The added modifier gives bonding strength, and increased flexibility to the thin-set. But again you have to be sure that the manufacturer has approved this method, and that the materials being used to do it are compatible. Note that ANSI specs REQUIRE that you use one manufacturer's brand for all components of this method. See ANSI A118.4 for details.
- GROUTING: Latex modified grouts should be used with glass tiles. You need the extra bonding strength of the latex and the added flexibility too. Extra latex can be added in this step as well to increase the advantages of the modifiers. Be sure to use products from manufacturers who recommend this procedure, and refer to ANSI 118.7 for more information.
*A word about epoxy setting materials and glass tiles. Epoxy bonding agents and grouts may not give you the movement allowances that glass needs, so be very careful using epoxy setting materials with glass. Check with the manufacturer before you decide to use epoxies in a glass installation.
And don't forget the expansion joints in glass tile installations when the dimensions of the installation call for them. The TCNA Handbook EJ171-09 will give you the particulars on this aspect of the installation.
The TCNA has not established standards specifically for glass tiles yet, but they are working on that, so stay tuned! And ALWAYS verify the setting methods and materials with the glass manufacturer and the materials manufacturer before writing the spec or doing the installation.