Glass and Buildings

Glass and Window film News from Klingshield

Johannesburg South Africa April 2011

Amongst all building materials glass has the unique property of transmitting light. In today’s world glass performs many functions in addition to the fundamental daylighting role.

Glass is a magical material originating from sand to becoming a beautiful clear see-through window.

In the window film business players need to understand the behaviour of glass as well as the visual, thermal and mechanical performances. Sound, insulation, heat gain and heat loss play an important role in the qualities of various types of glass.

Architectural glass lets in the light from the sun, the moon and the stars. In a building structure architects appreciate the crystal of glass, the evolving comfort and needs of the occupants and the flow of natural light to the interior. Windows are the eyes of any building and are good for the wellbeing of humans.

Glass Building Blue Sky

Klingshield has the leading edge and technology when it comes to applying a “skin” to glass, which is more commonly known as “window tinting, window film, glass coating, window protection, safety and solar control films”.

Window film improves the functionalities of glass by creating non reflective and reflective surfaces. Today glass is installed in walls, ceilings, floors and staircases, in all types of finishes from translucent, mirrored, coloured and transparent.

Glass will always have a functional place in buildings and is critical to comfortable living conditions. Windows have now become a selective filter with the application of films by reducing solar energy and heat loss.

Float glass is the most popular type of flat glass made in the world today. Float glass thicknesses range from 2mm to 25mm . Most float glass manufacturing lines have widths of 3m wide. The raw material of glass consists of basically three components – soda, lime and silica. Soda accounts for approximately 70% of the mix, lime 15% and silica 15%, with the addition of small amounts of magnesium, aluminium and iron. To create tinted glass manufacturers add metal oxides to the mixture. To get different shades of glass, manufacturers add iron, cobalt, selenium to produce colours of green, grey, bronze or blue.

Online coating of float glass is sprayed onto the glass to form a metal oxide layer which fuses to the surface.

For Offline coating manufacturers use a dipping method. Glass is dipped into a chemical solution then dried and fired. When fused onto the surface it has a uniform coating. Light transmissions of various glass depends on the nature and thickness of the coating. Coatings can be tailor made to allow various degrees of light, i.e. densities. These coatings reflect and absorb sunlight.

To manufacture mirrors, silver is used in the chemical process to coat the surface of the glass.

The chemical components for the float glass process are heated to a 1000 deg. C and is poured continuously from a furnace onto a large shallow bath manufactured from tin. The liquid glass floats onto the tin, spreading out and forming a level parallel surface on both sides. Various thicknesses are controlled by the speed at which a solid glass ribbon is drawn over the tin bath. The glass is then left to solidify. 90% of the world’s glass is manufactured using this process.

Laminated glass utilises two pieces of float glass with a plastic material or resin interlayer. The bonding is achieved by heating the glass interlayer sandwich under pressure in an autoclave.

Below is some technical information required by architects when evaluating the performance of film applied to float glass.

Film density depends on the thickness of aluminium or tinted coating deposited on the film. A thick coating i.e. a silver 20 reflective has a deeper colour and a greater reflectivity than films with higher reference numbers.

Glare is the contrast between bright and dark light viewed at the same time. By lowering the brightness glare discomfort is reduced. Therefore the lower the visible light transmission through a window the more comfortable the occupant will be.

Shading coefficient – a value used by airconditioner consultants to calculate the size of an airconditioning unit required in a building.

U Value is a measurement of thermal insulation denoting the materials ability to retain heat in a room.

Klingshield solar control window films improves the insulation qualities once installed on clear float glass by between 11% and 37% (depending on the film selected), whereby significantly reducing winter heating costs.

Ultra violet radiation – short wave ultra violet radiation is present in daylight and is the major cause of deterioration and fading of fabrics and furniture. Other contributing factors of fading are light of any kind and infra red radiation (heat).

Economy – Klingshield’s sun control window films applied to clear float glass costs less than any available reflective or tinted glass or exterior shading device. Since it can be used on existing glass, it dispenses with expensive replacement and construction costs.

Durability – All Klingshield’s sun control window films contain built in inhibitors to prevent any colour change. Accelerated aging tests carried out on these products show that there is no apparent deterioration in appearance or performance of the product over several years.

Specifications of Window Film:

Physical properties – thicknesses can range from ,025 mm to ,300mm
Tensile strength – 10,43kg to 15kg per cm of width
Melting point – 213,3% centigrade – 224.4% centigrade
Coefficiency of expansion – 15, 106cm/in/%%C

For more technical information on glass and window film, window tinting, glass coating, window protection, solar control window films and safety window films, please contact us.