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My last article ("Little Pieces of Murano," March 2004 PPP, pp. 28-29) discussed a technique used to create glass tiles that replicate the classic Murano look. Over the past several months, we have taken that process even further at Design America and have discovered how to create entirely new decorative effects. With simple additions such as decals, inserted objects and surface textures, you can add even more value to your finished products-and more profit to your bottom line.
Decorating with DecalsAdding decals to the surface of the tiles is one of the fastest and simplest ways to increase their value. Many decal suppliers carry products specifically for glass applications and can also instruct you regarding the temperature needed to successfully fire the decals. Keep in mind that the higher the temperature and the longer the firing cycle, the more rounded the edges of the tile will be. As a result, the finished tile might look much different than you anticipate. To avoid this problem and minimize any changes in the final product, look for low-firing-temperature decals (in the range of 600ºC). Additionally, be sure to use transparent decals if you want to retain the "semi-precious stone" look that the Murano style denotes.
We have also tried inserting decals into the tile and using a single-fire process. However, our initial experiments met with disappointing results. In some cases, the inserted decals disappeared during firing, while in others the decals changed color or became very pale and unattractive.
After some additional experimentation, we have developed the following guidelines for success:
- Insert the decal as high as possible in the mold to help it retain its original appearance.
- Avoid dark blue, dark red and bright yellow colors-these tend to disappear once fired (we do not yet know why).
- Lower your firing temperature from 1100 to 1000§C, and increase your firing cycle from 90 minutes (in a gas roller kiln) to 120 minutes. Although your manufacturing costs will increase, the process will smooth the firing curve and minimize damage to the decals.
A 3-D EffectInserting objects into the tile can achieve another decorative effect. The process is simple, but only certain objects can be used successfully. Additionally, the firing temperature must be carefully monitored to avoid drastic changes in the forms of the inserted objects.
Tests have indicated that food items are not good candidates because they cannot withstand the high firing temperatures required for Murano-look tile. Some items, such as uncooked pasta, simply vanish, while others, such as coffee beans, can affect the color of the tile (in this case turning it a coffee-brown color). However, research is ongoing to find a way to use these and other food items to add special effects and consistent color finishes to the tile.
Inserting metal products has also provided disappointing results. In most cases, the tiles have cracked because of an incompatible coefficient of expansion between the metal and glass. The ideal metal product for this application would have a very negligible coefficient of expansion, but we have yet to find it. Most metals tend to expand at temperatures over 900°C.
We have had the most success with inserting glass objects into Murano-look tile. Glass pieces in different shapes and colors can be inserted at different levels in the powdered glass. When fired, these pieces are affected only by the absorbed temperature of the powdered glass. The 1100ìC firing temperature will slightly change the edge shapes of the inserted glass pieces but will not melt them completely. The resulting design is beautiful, and the contrast of colors creates a look that is very different from that achieved by adding decorations to tile made from flat glass sheets.