The Varieties of Glass Tile:
Glass tiles can be categorized by manufacturing method. In this article we outline five main methods and surface treatments: smalti, fused, sintered, cast, slumped and etched.
Most tiles fall into a single category; some tiles, for instance slumped tiles, result from two or more processes.
Smalti tiles are typically colorful, textured, small format tiles – good building blocks for artistic mosaics.
“Smalti” is an Italian word, and refers to a glass paste or glaze made up of silica melted with sodium or potassium carbonate. Metals are added as stabilizing agents, as well as metal oxides ( for color). The paste is fired at high temperatures, then rolled out into a pancake-like slab that can be up to 6 inches thick. Once cooled, the slab is traditionally hand-cut into small rectangular pieces of tile.
In the fused manufacturing method, flat glass (usually float glass, such as glass used on car windshields) is cut into tiles shapes and then fired in a furnace. As glass is clear, it will show the tile underpay unless treated with color, so this method usually involves the addition of color – by adding it on top or under the glass. Fused glass tiles are often translucent tiles, with a layer of opaque color visible through the tile.
Fused tiles are often treated with an etching or other coating, for aethetic reasons, or to increase resistance to abrasion. Fused tiles can come in virtually any size – from mosaics to large format.
Sintered glass tile is made by pressing glass powder into dies and then heated until the particles fuse. These tiles are often sold in arrays of 1" × 1" squares, but can come in sizes up to 3" × 3".
In this method, color is either added into the powder or added topically after cooling. Unlike smalti tiles, sintered tiles tend to have a uniform look. With their milky, scratch- resistant finish, sintered tiles are known for their versatility.
Cast tile is made by inserting chunks of glass into a mold. The mold is heated until the pieces melt into each other and become a coherent mass. The result is a layered look. Most recycled glass tile products are made using this method.
Terrazzo glass tile is a cast method that combines an concrete amalgam with glass.
Slumped glass is glass that has been curved into a shape during firing. Slumped glass tiles are usually produced by melting plate glass into relief molds. On cooling, the glass assumes a curved or contoured shape.
Etched Glass Tile
These are fused glass tiles with a thin, translucent surface layer. This
layer is arrived at through one of three methods:
1. Abrasion. Devices can include sandblasters or laser cutters.
2. By applying an acid etch, such as hydroflouric acid, to the surface.
3. By applying an additional, cloudy glass surface to the top of the tile.