Glass Science and Production

Flashcards covering the history, chemical composition, classification, coloring agents, forming processes, and finishing techniques of glass based on lecture notes.

What are two examples of natural glass mentioned in the notes?

Obsidian and Fulgurite (formed by lightning strikes).

How is the molecular structure of glass described?

It is an amorphous material with disordered molecules like liquids, but it is solid and rigid like crystals.

What is the primary base material (Former) used in glass composition?

Silica ($SiO_2$), which comes from sand.

What is the function of Fluxes such as Sodium carbonate or Potassium carbonate?

They reduce the melting temperature of the glass.

What is the role of a Stabilizer like Limestone (calcium carbonate) in glass production?

It prevents glass from dissolving or degrading and makes it stronger, harder, and resistant to water.

What characterizes 'Hard Glass' in terms of heat and resistance?

It has a higher heat resistance and is more resistant to scratching.

Which type of glass is known for remaining workable for a longer period before cooling?

Soft Glass.

What is the melting temperature of Borosilicate Glass (Pyrex)?

$1500\,^{\circ}\text{C}$.

According to the Mohs Hardness Scale, where does glass typically fall?

$5.5$ to $6.5$, with Diamond at $10$ and Talc at $1$.

What is the composition and melting point of Crystal glass?

It is composed of $SiO_2$ and $24\%$ Lead oxide, with a melting point below $1000\,^{\circ}\text{C}$.

Which chemical additive is used to produce Red colored glass?

Gold chloride.

How do Iron oxide ions ($Fe^{2+}$ and $Fe^{3+}$) affect glass color?

$Fe^{2+}$ creates a greenish tint, while $Fe^{3+}$ creates an amber color.

What is the function of Manganese oxide in coloring glass?

It produces Pink or Purple colors and is used as a neutralizer for green.

What effect does Silver salt have on glass?

It creates an Iridescent Effect.

What are the two primary machine processes for industrial glass forming?

1. Blow and Blow; 2. Press and Blow.

What are the steps in the Studio Glass forming process?

Gathering (at $1150\,^{\circ}\text{C}$), Marvering (rolling on a blowpipe), Shaping (via gravity/swinging), Reheating in the 'Glory Hole', Transferring from blowpipe to punty, Final shaping, and Annealing.

What is the temperature of the Annealing oven?

$500\,^{\circ}\text{C}$.

How is 'Cast Glass' produced?

It is poured into a mold.

What is Lampworking and what type of glass does it typically use?

The creation of small objects using a flame and borosilicate glass.

Describe the Float Glass process for creating flat glass sheets.

Molten glass at $1500\,^{\circ}\text{C}$ floats on top of molten tin to ensure a flat surface; speed and stretching control the thickness between $2\,\text{mm}$ and $25\,\text{mm}$.

Why is float glass cut diagonally during the production line?

Because the glass ribbon continues to slide on the system while being cut.

What finishing technique is used to create frosted surfaces or a matte appearance?

Sandblasting.

What is the difference between Enamelling and Decals in glass finishing?

Enamelling uses coloring powder or enamel paint, while Decals involve transferring pre-printed images onto the glass.

What materials are used for the thin metallic coating in Plating?

Silver, gold, or aluminium.