Glass

Question 1

Explain the brief history of glass

Answer 1

First used in glaze on ceramics-3000 BC
First all glass vessels-1500 BC
First blow pipe for glass blowing-30 BC
First window glass-50 AD
First plate glass in France-1688 AD
Lead/flint glass made in England-1764 AD
Continuous sheets of glass in Belgium-1902 AD
First Pyrex glass made in USA-1915 AD
Float glass made by Pilkington-1959 AD

Question 2

What are the 5 traditional types of glass

Answer 2

Spun
Blown
Drawn sheet
Plate
Float

Question 3

How is drawn sheet glass made

Answer 3

Molten glass is drawn up from the furnace
and passed over rollers
the separation between the rollers determines the thickness of the glass

Question 4

How is plate glass made

Answer 4

Same as drawn sheet but surface is
ground and polished after manufacture

Question 5

How is float glass made

Answer 5

Molten glass is poured over a molten bed of tin
which gives a perfectly flat piece of continuous glass

Question 6

What is glass made of

Answer 6

Sand-at least 60%
Cullet
Limestone
Dolomite
Soda ash

Question 7

What are some other additives and what do they do

Answer 7

Lead-stops radiation penetrating glass and surface lustre
Borax-produces a glass which is resistant to thermal shock
due to low thermal movement

Question 8

What are the six desirable characteristics of glass

Answer 8

Appearance/transparency
Strength
Solar heat transmission
Durability
Thermal insulation or movement
Sound insulation

Question 9

Explain what is meant by the property appearance

Answer 9

Glass should be more or less transparent (depends on function)
and mostly colourless

Question 10

Explain what is meant by the property strength

Answer 10

Glass needs to be strong enough to resist wind loads
Loads and impacts
Thermal stresses

Question 11

Explain what is meant by the property durability

Answer 11

Normally glass is sufficiently durable however it can be attacked
by phosphoric acid or hydrofluoric acid

Question 12

Explain what is meant by the property thermal insulation

Answer 12

Glass must be able to hold in heat for houses
can be improved by double or triple glazing

Question 13

Describe the behaviour of glass in fire

Answer 13

Glass is non combustible
meaning it either breaks or
melts
max time of fire resistance is 30 mins

Question 14

Explain how the greenhouse effect works with relation to glass properties

Answer 14

Short wave infrared radiation is allowed through glass
The wave then loses energy and becomes long wave radiation
which cannot travel through the glass again and therefore
bounced around inside the structure

Question 15

How is toughened glass made

Answer 15

Glass is heated uniformly until it’s softening point
and then cooled rapidly by jets of air