Glass is one of the most important materials used in building construction and technology. It is mostly seen on facades, doors, windows, railings, etc. It is well known for its visual see-through and light transmission. Glass connects indoors to outdoor and outdoors to indoors. In this article, let us go through types of Manufactured glass, architectural glass, and common glazing materials.

Glass in Architecture is used for

• Facades – Fenestrations (doors, windows), cladding in facades
• Building construction – Glass Partitions walls, floors, skylights, roof panels, display shelves in showrooms
• Glass in insulation – glass wool

It is made up of a number of materials such as sand, soda ash, and limestone. Calcium sulfate and dolomite are added in smaller amounts including the addition of broken glass or cullet. It is formed by the high-temperature fusing of silicates, alkalis, lime, and other materials. Minerals are added to obtain colors.

Manufactured Glass

Glass can be manufactured in sheet form from 1/2″ to 2″ (2 to 50mm) thick and used for various purposes. These panes are produced in three basic ways:

• Sheet
• Plane
• Float

Sheet glass is produced by drawing out the molten glass and subjecting both sides to heat. The resulting faces are not truly parallel since it is not further treated. This technique has been replaced by better methods.

Plate glass is ground and polished after being drawn from the molten state, producing more parallel surfaces.

Float glass (commonly known as window glass) has replaced sheet and float glass. It is made by floating molten glass over a molten metal such as tin, producing an even layer of glass that ends up polished on both sides.

Glass is also melted and forced through small orifices to produce thin glass fibers. These are used in manufacturing building insulations and various fibers for textiles.

The thickness of Float glass varies from 3mm-25mm.

Non-sheet Products and Sheets Products

Non-Sheet Products Include

• Glass Fibres
• Glass wool
• Cast glass
• Glass Blocks
• Glass Pavers
• Cellular of Foamed glass

Sheet Products Include:

• Traditional blown and drawn glasses
  • Suitable for conservation work where old glass requires replacement.
• Float glass
• Curved sheet glass – glass sheets bent into curvatures.
• Self-cleaning glass – The invisible hard surface coating has two special features.
  • The surface incorporating titanium dioxide is photocatalytic, absorbing ultra-violet light, which with oxygen from the air, breaks down or loosens any organic dirt on the surface.
  • the surface is hydrophilic, causing rainwater to spread evenly over the surface, rather than running down in droplets, thus uniformly washing the surface.
• Clear white glass
• Patterned glass – glass with strong patterns and designs
• Screen printed glass – ceramic frit is screen printed onto clear or tinted float glass.
• Acid-etched glass and sandblasted glass – a small range of patterns.
• Various types of Architectural and decorative glass are mentioned below.

Architectural glass

Architectural glass is also made in different thicknesses, strengths, colors, tints, and finishes. It can be frosted, ribbed, pebbled, or curved to suit a variety of purposes.

Safety glass

(commonly called annealed) :

• Resistance to breakage from impact and thermal stresses.
• Tempered, wire, laminated, or security glasses are available to help prevent injury.
• Tempered (or toughened) glass is used as the most common form of safety glass.
  • Toughened glass cannot be cut or worked, therefore all the cutting, drilling, and polishing have to done in advance.
  • It withstands considerable extremes of temperature.
• Safety glass can also include fire-resistance glass, which is used in fire-rated partitions that can be made with wired glass/laminated/toughened glass.
• Toughened calcium-silica-based glasses can achieve 90 minutes of fire resistance with respect to integrity.

Insulating glass as architectural glass

• Made as double or triple glass to reduce heat loss and gain in buildings.
• It consists of two or three layers of glass that are separated and sealed, with an air space (or gas) between layers. These spaces vary from 6mm to 12mm.
• Insulated glass can be produced as uncoated glass or coated, whereby one layer can have a thin layer of metal oxide applied that decreases the transmission of heat through the glass.

Common glazing materials

Annealed glass

• Common glass is often called clear window glass.
• General usage in doors, windows, mirrors, glass shelves, etc.

Laminated glass

• It is produced by bonding layers of glass together with an inner plastic layer of polyvinyl butyral (PVB); or a low-viscosity resin; varying inner plastic layers can control heat, glare, and sound transmission.
• Increases impact resistance.
• Heat-strengthened glass is typically used in Laminated glass.
  • Upper stories, corners’ of high buildings (where resistance to wind pressure is necessary), spandrels
• Used as safety glass, roof panels, and overhead glazing in buildings and in motor vehicles.

Tempered glass

• Heat-strengthened during manufacturing, difficult to break.
• Used as Entry and shower doors, windows subject to impact.

Wired glass

• Holds together when subjected to high temperatures, impact, and air pressures.
• Used as common safety and fire-resistive assembly in buildings, overhead glazing.

Reflective and heat-absorbing glass

• Reflective glass and films reflect or absorb solar radiation.
• It has a thin film of transparent metal or metal oxides bonded to the glass surface to reflect the sun’s rays.
• It is produced by adding coloring agents (usually gray, green, or bronze tints) during manufacturing.
• Metals are integrally cast into the glass and are charged electrically to become opaque or clear, depending on the need. These types are often called electrochromic glazing.

Decorative glass

Decorative glass is an expressive material that can be used in both utilitarian and decorative or aesthetic treatments.

Hand-Blown and Molded Glass

• It is the oldest and most popular art glass form. It is made by dipping a hollow metal rod into molten glass material and blowing a bubble. Before the glass cools, the glassblower uses tools to roll, twist, or shape it, creating a distinct, handcrafted look.
• Molded glass is a mass-production of the hand-blown process. Glass is blown or pressed into molds during the molten stage. Many glass items are made this way as seen in dishware and bottles.

Engraved and Etched Glass

• Engraved Glass is made with wheels and various abrasives, to cut the surface, producing fine decorative and pictorial effects.
• To produce etched glass, either sandblasting or acid techniques are used to create art on the glass surface after the glass is blown or cast.
• The technique of etching produces a shallower design than engraving, and it is often used to imitate the more deeply incised engraved technique.

Beveled, Leaded, and Stained Glass

• Beveled Glass is made by grinding and polishing the edges of a piece of thick glass at an angle. Beveling is used for leaded glass windows, mirrors, and doors and in insets in wooden frames for decorative purposes.
• Leaded glass generally refers to transparent or colored glass, such as in a window.
• Stained glass refers to glass that has been colored by glazing, pigmenting or painting. It is set in lead or strips of copper foil for decorative uses and items such as lampshades and windows.

The degree of privacy afforded by glasses depends on

• Pattern of glass
• Relative lighting levels on either side
• The proximity of any object to glass

Other Specialist Glasses

• Observation glass – used where unobserved surveillance is required.
• Mirror glass
• Anti-reflection glass – reduces surface reflection, thus increasing surface transmittance.
• Alarm glass – a series of wires are installed into the intruder alarm system to get activated when the glass is broken.
• Dichroic glass – creates optical interference effects.
• Sphere glass and cracked glass – are used in feature walls as it consists of an array of glass hemispheres.
• Anti-bacterial glass
• X-ray protection glass
• Sound generating glass

Smart Glasses

Smart glasses change their optical and thermal properties under the influence of light, heat or electric potential. These glasses offer highly responsive dynamic climate control to building facades.

• Photochromic glass
• Thermochromic glass
• Electrochromic glass
• Electro-optic laminates
• Intelligent glass

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