Glass - LeFonch

Glass is commonly used for its transparency, ease of sterilization, compressive strength and other properties.

Characteristics of Glass

Glass is hard and brittle.
It an amorphous solid, meaning it does not have a clearly defined shape or form.
- Thus it has no internal crystalline structure like metals do.
Glass is made from readily available domestic materials such as sand, soda ash, limestone and cullet.
- Cullet is the industry term for furnace-ready recycled glass and it is necessary when making glass.
Examples of glass include:
- Borosilicate glass (resistant to thermal shock)
- Soda-lime glass (bottles, containers)
- Reinforced/wire mesh glass (safety windows)
- Laminated glass (glass-plastic sheet combo)
- Tempered/toughened glass (balanced internal structure cause glass to crumble at breakage)

Color of glass contributes to its aesthetic and functional (dimming, shading) properties.
Color can distinguish a glass product, shield its contents from unwanted ultraviolet rays or create variety within a brand category.
Color can be obtained by simply adding small quantities of different oxides:
- Chromium (for green)
- Cobalt (for blue)
- Nickel (for violet/brown)
- Selenium metal (for red)

Transparency is the main property of glass which allows vision of the outside world through it.
The transparency of glass can be from both sides or from one side only.
In one-side transparency, glass behaves like a mirror from the other side.

Strength of glass depends on modulus of rupture value of glass.
In general glass is a brittle (easily shatters into many shards) material but by adding admixtures and laminates we can make it as stronger.

Glass can be molded or blown into almost any shape during liquid state.
Workability of glass is a superior property of glass, but needs high temperatures for shaping.

The visible fraction of light that passing through glass is the property of visible transmittance.
While transparency is the ability of glass to allow vision to the outside world, transmittance is the ability of glass that allows light to pass through.
- Dark glass might be transparent but have low transparency.
- Frosted glass might have high transmittance but low transparency.

Glass is the only-widely used packaging material considered "generally recognized as safe".
Glass does not lose particles and is not affected by chemical substances.
It is easily sterilized for hygienic use.
- This makes glass very important for food and medical products.

Glass has developed from a luxury material to a more common and widespread material, with a large range of applications:

Recovery and separation of glass types, separating contamination and oxides are vital for optimal recycling.
This is why your brown bottles are separated from the green ones.

Laminated glass has a layer of film in between two sheets of glass.
This makes it so that the glass doesn't shatter into shards when broken, making it safer to use.
Different laminates can give the glass different properties, such as fire-resistance.
It is often used on car windshields and fire-proof doors.

Tempered glass shatters into small, dull, pebbles.
It is useful for door windows on cars, as it reduces the risk of cuts during a crash.