Translucent Materials

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Special coatings Optical coatings are appropriate for spe cial uses in medicine, and in lighting and industry. • Cold-mirror coatings work like reverse” low-E systems by reflecting the vs ble wavelengths and transmitting the lP range. They are used in reflectors for dichroic lamps or projectors. - Anti-reflection coatings reduce the reflecton from glass panes from about S % to about 1 %, thus increasing light transm ssion. They are used for glazing showcases or advertising panels (Ami ran®, Mirogas®, Luxar®). • Dichroic coatings cause a shift from transmission to reflection in the visible light range. This breaks the light down into complementary colours. Glass of this kind is used for special fil ters in measuring and lab technology. The architect and glass specialist James Carpenter used dichroic g ass for a lot of his art-in-building projects (ill. 12). - Electroconductive coatings are layers and layer systems based on indium oxide (ITO) and silver. They form elec trically conductive coatings that can be used for EC (electrochrome) coat ng, for examp e. • Dirt resistant coatings stop glass from getting dirty as a result of environmen tal influences and make it easier to clean. This effect s produced by changing the wettability properties of the glass surface. Hydrophobic coat ings make the water form droplets that run off very quickly Hydrophilic coat ings make the water spread out and form a transparent film. Thick coatings Thick coatings comprise protective and enamel coatings and laminated plastic films. They are almost all produced offline. • Protective coatings Protective lacquer is applied to protect the thin layer of silver on a mirror. It is produced by fogging: the mirror is drawn through a fog created by a slit nozzle. - Enamel coatings Enamel ed glass is given a ceramic coating that is resistant to wear and tear and to weathering. The ename coating is created by applying a frit of finely ground glass with various addi tives and colour pigments to the glass and then firing it on. Enamelling can cover the entire pane, or be applied in printed patterns. Roller application cov ers the whole surface: the layer of col our is applied with a pressure roller. A dosing roller controls the thickness of the layer. Patterns of dots, lines and bars are created by a screen-printing process, evenly or with flow-out. The pailem is transferred to the pane by a stencil, and each layer is allowed to dry 14 separately if there is more than one col our (ills. 13 and 14). Enamelled patterns can be made into light panels. Here artificial light is from light-emitting diodes is introduced from the edge of the pane, v sible through the printed enamel. Light-emitting diodes make all kinds of colour grading possible (ill. 15). Conductor tracks with conduc tor gel are used for car panes with inte grated heating or aerials, for example. Laminated plastic film Plastic film, which bonds the splinters together, can be applied to glass to mini mize the danger of injury when a pane of glass breaks. There are also plastic films on the market offering thermal insulation and sunscreening. These products have not yet become accepted in Europe. The film s applied to the glass from a feeder rol dur ng manufacture. 15 4, 1%~ Glass as a building material Surface treatment
Glass as a building material Multilayered glass — Laminated glass 16 Walkway link in Rollerdam Laminated glass ttoor stabs (2 xiS mm) on two gtass supports Architecis; Dirk Jan Postal, Kraaijvanger urbis, Rollerdam Structural engineering: Rob Nisse, AST Vetp 17 Examples ot different compositions for fire-retard ant gtass 18 Butlet-resistant glass 19 Fire retardant glass, demonstration ot thermal insulation using Pilkington Pyrostop’ 18 Multi-layered glass Multi-layered construction makes it ~O5Sl ble to combine glass panes with and without coating and with intermediate spaces of varying depths. This make it possible to build in various thermal insula tion and sunscreening measures. Laminated glass Laminated glass is made up of one or more panes with an intermediate layer. Laminated glass with no safety features can be used for sound insulation or deco rative purposes. Cast resins and various kinds of plastic membrane can be used as the intermediate layer: transparent, tinted and patterned, UV absorbent and IA reflective film, film with wire inlays for security, alarm or heating purposes. Cast resin is poured between the panes and then fixed by UV radiation or chemical treatment. Plastic film is laminated between the panes. It is also possible to buy laminated glass with intermediate metal mesh layers (OkaTech®), veneered wood (Chrisunid®), and glass mat (Ther molux®). It is even possible to fix light-emitting diodes between the layers, activated by a power supply from a transparent conduc tive coating (Power~Glass®). 16 Laminated safety glass The commonest use of laminated glass is laminated safety glass, which is made with an intermediate layer of polyvinyl butyral (PVB) film. If the glass breaks, the splinters stick to the elastic PVB film, con siderably reducing the risk of injury. Another advantage of laminated safety glass is that unlike float and tempered safety glass it does not shatter into frag ments, but can hold back people or objects that cannon into it where neces sary. Typical uses of laminated safety glass are for overhead glazing and glass used to prevent falling, like glass para pets or floor-to-ceiling glazing (ills. 11, 14). Laminated safety glass is made by plac ing PVB film with a thickness of 0.38 or 0.76 mm between the glass panes and pressing them together in an autoclave with heat and low pressure. Tempered safety glass or partially tempered glass are often used for laminated safety glass, as they are stronger than normal float glass. Partially tempered glass has the advan tage over tempered safety glass when it breaks that it gives better residual struc tural stability because larger pieces stick to the intermediate layer.
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Translucent Materials

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