Properties of Glass
Reflect, refract and Transmit Light
Types of Glass
• There are many different types of glass and various ways in
which glass can be categorized.
Types of glass as per application:
• Automotive glass
• Architectural glass
– Annealed glass, Laminated glass, Tempered glass, Wired glass
• Decorative glass
– Molded glass, Etched glass, stained glass
Types of glass as manufactured process and special features:
Bullet proof glass
Solar control glass
Self cleaning glass
• It is also called soda-lime glass or clear glass.
• It is produced by annealing the molten glass and is clear and
• Widely used for fenestrations in residential buildings,
commercial spaces, furniture pieces, etc
• Uses: It is used in the manufacture of glass tubes and
other laboratory apparatus, plate glass, window glass, etc
• Tinted Glass
– Melt colorants are added for tinting in the normal float glass.
– For example, iron oxide is added to give a green tint.
– Used for window panels, glass fancy articles, decorative tiles, etc.
• Reflective Glass
– Glass is treated with a metallic coating that cuts off solar heat.
– This coating also gives a one-way mirror effect, preventing visibility from
– outside thus maintaining privacy.
• Wired Glass
– Steel wire mesh is placed in glass during rolling operation. This glass is fire
– Used for roofs, skylights, fire-resisting doors and windows
(1) Soda-lime glass or commercial glass
(2) Potash-lime glass : Bohemian-glass or hard-glass. It is mainly a mixture
of potassium silicate and calcium silicate
(3) Potash-lead glass :This is also known as the flint glass. It is mainly a
mixture of potassium silicate and lead silicate. (Ex: electric bulbs,
lenses, Prisms, etc. )
(4) Common glass : This is also known as the bottle glass. It is prepared
cheap raw materials. It is mainly a mixture of sodium silicate, calcium
silicate and iron silicate (Ex: Medicine bottles)
• Borosilicate glass: Most of us are more familiar with this type of glass in
the form of ovenware and other heat-resisting ware, better known under
the trade name Pyrax. Borosilicate glass is made mainly of 70 % to 80 %
silica and 7% to 13% boric oxide with smaller amounts of the alkalis
(sodium and potassium oxides) and aluminium oxide
• This glass is widely used in the chemical industry, for laboratory apparatus,
for ampoules and other pharmaceutical containers, for various high
intensity lighting applications and as glass fibres used in the reinforced
plastics to make protective helmets, boats, piping, car chassis, ropes, car
exhausts and many other items and also in textile industry.
Manufacture Of Glass
The procedure adopted in the manufacture of glass may broadly
be divided into the following five stages:
(1) Collection of raw materials
(2) Preparation of batch
(3) Melting in furnace
Catalysis is the process of increasing the rate of a
chemical reaction by adding a substance known as a
• The process of blow moulding consists of forming a hollow object by literally blowing
a thermoplastic hollow cylinder called parison or perform, in the shape of a mould cavity.
• The parison is dropped between two open-mould halves, which are shaped to the desired product.
Once the parison has enough length, it is heated and blown with pressurised gas, generally air, against
• The product is cooled and crystallised until it is removed from the blow mould to avoid deformation
Calendaring is a speciality process for high-volume, high quality plastic film and sheet, mainly used for PVC
as well as for certain other modified thermoplastics.
The melted polymer is subject to heat and pressure in an extruder and formed into sheet or film by
calendaring rolls. The temperature and speed of the rolls influences the properties of the film
• The plastic is prepared in liquid form, in some cases the resin is naturally a liquid and in
others a granular solid is liquefied by heat.
• The liquid plastic is poured into a closed mold and air bubbles are removed. The plastic
is cured at room temperature or in an oven at low heat.
• The cured plastic is then removed from the mold