Toughened Glass

(Tempered) safety glass is produced by subjecting annealed glass to a process of heating and rapid cooling. This creates a balance between compressive and tensile stresses. If the glass is broken the balance of the stresses is destroyed, and this results in a close meshed network of small, mostly blunt edged glass fragments. This reduces the risk of injury considerably

The properties and structural use of toughened glass
Recent architectural trends have increased significantly the use of glass in buildings not only as non-structural facade elements but also as important load carrying structural elements, i.e. as integrated load carrying elements in facades or as distinct structural elements such as columns – elements for with materials such as steel and concrete traditionally are used.

Glass has many excellent mechanical properties which make it a perfect choice for structural use: high compressive strength, good stiffness to weight ratio, good resistance to aggressive environments and good long term performance. Glass however is extremely brittle and this brittleness poses serious limitations in its structural use. The brittleness makes glass extremely vulnerable to the presence of small defects in the surface which in turn makes its tensile properties unreliable. Further, the brittleness prevents any inelastic deformations before failure which is usually a requirement in structural safety.

Development of on one hand toughened and heat treated glass and on the other laminated glass has pushed the structural applicability of glass significantly. Toughening of glass introduces residual compressive stresses in the surface and the edges of glass elements, stabilizing the micro-defects present in these areas. Heat treatment of glass introduces these residual stresses to a lesser degree, while laminating of glass typically combines various types of glass, hardened, heat treated or just plain float glass in such a way that ductility and integrity at failure is achieved. Combining these techniques for controlling the effective glass properties with innovative ways of designing joints and connections a new world of structural opportunities has been opened using glass as a structural material.

There is still however a lack of material specification tools, relevant test methods, structural design methodologies and standards. This makes the design procedure for structural use of glass cumbersome and often the designer has to resort to full scale destructive testing of key structural elements. The present project should be seen as a step towards establishing a design methodology for joints in hardened glass including bolted friction and bolted pin connections. Ultimately the results should allow for development of a methodology for material property specification and testing.

Glass Fussion Work

Every progress in technology brings something new in every domain. Stained glass manufacturing is easier thanks to a wonderful technology called fusion. Many stained glass artists can see their dreams come true thanks to this process.

Glass fusion is a process meant to combine pieces of glass into one beautiful stained glass pane.

Here is how it works-

The stained glass artist will choose the big glass pane taking into account the colors, dimensions and the overall aspect of what he wants to create. On the big pane, he will place smaller colored glass pieces in the shape that he wants to obtain. These pieces will be arranged like the pieces of a puzzle.

The freedom to create is absolute; using this technique, you can place the pieces however you want, even one on top of the others. The stained glass artists are aware of the properties the glass has. In this operation, the coefficient of expansion is very important. Some glasses will shatter or break during the fusion process, so do not try this at home unless you have the necessary equipment and the required glass pieces.

All the pieces will form the theme of the “painting”. For better results, the smaller glasses will be fixed in the desired position with special glue. This glue is will not remain after the fusion is over; it will actually vanish, leaving no trace at all on the resulting glass pane.

Once the structure is glued and ready, it will be placed in a special kiln and “cooked” for about 15 minutes. The temperature will range from 500 to 800 degrees Celsius depending on the complexity of the glass pane. During this process the glass will literally melt, one onto the other. After it cools down, we will have a nice stained glass pane ready to hit the stores.

This technology gives stained glass manufacturers and artists more freedom to manipulate the glass better or in order to create astonishing effects. This way the resulting glass will be one piece. Painting and gluing the pieces together have their disadvantages. Paint will wear off its color with the passage of time and the traditional way of gluing the glasses together is very pretentious.

Stained glass appliances are various and the beauty of this art is astonishing. The effect created by the light passing through a stained glass pane is fascinating. Either you want a stained glass window or an interior decoration for your apartment, every piece of glass has its story and it is good to listen to it.