Glass

Glass is a transparent, amorphous solid produced by melting sand.

Why is glass so loud?

Essentially, what causes the noise is that glass is a very stiff material, and resonates for a long time when struck. You can hear this whenever two glasses clink together. When glass is broken each piece is able to 'ring' independently. The frequencies they produce will depend on their size and shape, and the combined effect can be extremely loud. This is especially true if it was formerly a large piece of glass, such as a doorway, because it will produce many pieces.

Most glass is soda-lime glass.

Contents

1   Prince Rupert's drop

A Prince Rupert's drop is a toughened glass bead created by dripping molten glass into cold water, which causes it to solidify into a tadpole-shaped droplet with a long thin tail. Droplets are able to withstand a blow from a hammer on the bulbous end without breaking, but explode if the tail end is even slightly damaged.

The interior cools more slowly. As it cools, it contracts and attempts to pull the surface in with it, but it can only do a little since the surface has already hardened. It creates an internal layer that is forever under tension. [1] This tension gives it its compressive strength. When the stress is released, the whole thing shatters.

The drops are named after Prince Rupert of the Rhine who brought them to England in 1660. The unraveling of the principles of their unusual properties led to the development of toughened glass, patented in 1874. [1]

2   Uses

2.1   Automobile windshield

Automobile windshields are made of thick pieces of soda-lime glass. They are laminated; they are composed of two pieces of glass bonded together by a resin. The resin does two things: it gives it added strength and holds the glass together on impact. Windshields have been made of laminated glass for over a century. [1] But they are heavy. [1]

2.2   Containers

A carafe is a glass container without handles used for serving wine and other drinks. Carafes are used for serving water and juices where the shape of the container doesn't affect the characteristics and the taste of the liquid that it's holding.

2.3   Mirror

Creating a mirror using silver nitrate.

3   Classification

3.1   Borosilicate glass

Borosilicate glass is glass ... It is designed for handing rapid changes in temperature, where regular glass would shatter. It it used to produce Chemex's.

3.2   Tempered glass

Tempered glass is glass with high compressive strength.

4   Properties

4.1   Compressive strength

The compressive strength of glass ... It can be tested by dropping a steel ball hammer attached to an axle to repeatedly simulate a 1m drop.

It can also be tested by firing a bullet out of an air cannon.

5   Obsidian

Obsidian is a volcanic glass.

The edge is far thinner than that of a forged steel scalpel. When obsidian gets really thin, it retains a smooth edge, which metals can't do. Metal edges under a microscope are jagged and look more like saw teeth than a smooth blade.

Thickness and jaggedness are both properties that reduce cutting efficiency. Sawblades are jagged because they spin quickly and the teeth help the blade bite into the material. (Using a non-serrated blade with wood does not work well.)

Cutting different materials requires different blades.

The difference between a knife and a saw is that a knife makes one cut through whatever it is you're separating, while a saw makes hundreds or thousands of small cuts removing material.


Obsidian knives are rarely used during surgery because obsidian is very brittle, so there's a chance it will break and fall into the wound.


It all boils down to obsidian's atomic bonding energy verses that of metal and how these values compare to the materials' free surface energies. Think of it this way: There's a really strong wind storm and two, separate groups of people are caught outside: a group of children and a group of powerlifters. In each group, everyone is holding onto each as to not get blown away. Obviously, the people on the outside of the groups are the most vulnerable because less people are around them and able to hold onto them. The powerlifters are like the atoms within obsidian - strongly holding onto each other and unwilling to bend. In order to not be blown away, those on the outer perimeter only need the help of one other person. The grip strength of these guys is so strong that their group can form an arrow with only one person positioned at the point, holding onto just one other guy. On the other hand, the children are like metal atoms. The children on the outer perimeter of their group need to be held onto by at least three other kids in order to avoid being blown away because their grip strength is much weaker than that of the powerlifters'. So, if this group tries to form an arrow, the arrow's tip will have to be composed of several children (instead of one) - effectively blunting the tip. The second thing to consider is the flexibility of these groups. The powerlifters are all about gainz and rarely stretch. Therefore, if an unusually strong gust of wind hits the group of lifters, their arms will only be able to stretch a small amount before the lifters just let go. This is comparable to how obsidian breaks; it cleaves and forms sharp edges. Conversely, the kids are very flexible. When that strong gust of wind hits them, they're able to stretch and bend a lot, instead of completely letting go. Rather than breaking cleanly, their group will deform in order to accommodate the strong force.

Obsidian can achieve a thinner edge because of its ionic bonds and amorphous structure. Not only are these bonds very rigid, but they are very stable and require but a few atoms, but they will not easily allow the reactions to change the atomic structure.

Metal on the other hand is held together by metallic bonds (i know it sounds silly but it basically means metal atoms share electrons to be somewhat stable so there needs to be a lot of the them together) and has a crystalline lattice. So even if a metal were to be sharpened to be as thin as an obsidian edge, it would not be stable or it would corrode almost instantly (high surface energy is unfavorable).

6   History

[2]

Since wine rather than hot tea was their source of safe water, the use of glass for containers, later for windows, mirrors, & instruments such as prisms and primitive (e.g. spherical) lenses was far more common in Europe than in other cultures.

Glass allowed chemists to safely contain yet observe. It played a key role in the 17c scientific revolution -- microscopic biology, telescopic astronomy, and global exploration. The barometer led to understanding air & vacuum, enabling the steam engine.

Before the solid-state transistors & integrated circuits that gave it the name "Silicon" Valley, that region was a locus of innovation in glass vacuum tubes, the key mid-20th-century tech for radios, televisions, guidance & control, electronic warfare, radar, & early computers.

7   References

[1](1, 2, 3, 4) Corning Incorporated. Nov 19, 2014. The Glass Age, Part 2: Strong, Durable Glass. https://www.youtube.com/watch?v=13B5K_lAabw
[2]Nick Szabo. Comments on "Glass: A World History" by Alan Macfarlane and Gerry Martin.