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A different process can be used to create an end product that looks like, and has some of the characteristics of, semi-precious stone. Just a few pieces inserted in a stone or ceramic mosaic enhance the beauty of that mosaic-and generate higher revenues. The process originated in Italy centuries ago, on the island of Murano, and today, Murano glass is still world-renowned for its beauty. However, achieving the Murano look is no longer limited to Italian artisans. With the right techniques and equipment, virtually any glass tile producer can replicate the classic Murano style.
Layering Glass PowderThe process consists of applying different layers of glass powder (vitrosa) in a refractory mold. (Both the glass powder and molds can be obtained at many art and pottery supply stores.) First, a thin layer of glass powder is applied, followed by a second, thicker layer. A layer of colored powder or a design is added, and then another two layers of glass powder are applied.
The result is a mold filled with over 600 grams (about 1.33 lbs) of glass powder. (Anti-slip additives should also be included when the finished product is to be used in floor tile applications.) At each step of the process, the material must be well pressed and compacted to render the finished tile more durable and able to withstand shock, as well as brutal temperature changes. Using a silkscreen machine to apply the powder can help ensure that the layers are even and well compacted within the mold.
The filled mold is fired in a gas roller kiln at 1100∞C (2012∞F) for 90 minutes-this combination of time and temperature allows all the glass particles to melt and form a solid mass of glass. The mass is allowed to cool for at least 40 minutes and is then removed from the mold and cut into different sizes by hand or with a continuous cutting machine. The tiles are then loaded onto kiln shelves and fired again at 800∞C (1472∞F) for 45 minutes to smooth and round the edges.
Over the past year, the resulting product has become a benchmark in interior design. Its innovative and bubbly look, opacity, durable surface and aesthetic-enhancing qualities-as well as the ability to have designs and objects embedded in the tile-are highly appreciated by both interior designers and consumers. Unlike conventionally made glass tiles, which often reveal the defects in the glass sheets, tiles produced through this process are typically flawless and can be sold as semi-precious stones. As a result, they command a much higher price on the market.
Mastering the TechniquesThe process enables glass tile producers to offer a variety of original solutions in the full color spectrum with the typical transparency and elegance of glass, while avoiding the problems frequently encountered in glass products, such as sudden bursts, cracks, and slippery and easily scratched surfaces.
No shortcuts or "miracle formulas" are available to achieve this high-quality product; instead, each producer must take the time to develop his or her own unique process and designs. However, following a few basic criteria can help ensure success:
- A gas roller kiln is a must. All other kilns have proven to be less efficient and much more expensive to use.
- Both the firing and ambient temperatures in the kiln must be carefully controlled to ensure that the firing curve is smooth. Temperatures must be increased very slowly, and the cooling process must also be done over a long time period to avoid cracking the tile.
- The firing cycle should be as long as possible. Ninety minutes in a gas roller kiln is minimum to ensure uniform melting and a high-quality look.
Once the fundamental techniques have been mastered, producers can experiment with different design effects, such as inserting objects in the glass tile without having them melt and disappear, creating air bubbles throughout the tile, or achieving a marble look or unique color. Such value-added products can catapult producers beyond basic glass tile-and into the realm of higher sales and profits.