Martin McBride
Carterton U3A
ORIGINS OF GLASS
DECORATIVE GLASS MAKING
EARLY FLAT GLASS MANUFACTURE
MODERN GLASS PRODUCTION
WHO AM I … WHAT DO I KNOW
ABOUT GLASS
 Applied Chemistry Specialised in Glass Technology
and Fuel Technology
 One of the “Old School”
 Joined Pilkington Glass in 1963 and retired from
Pilkington Glass in 1997.
 Worked in Mexico, Australia, Sweden, South Africa,
Visited Germany, France, Denmark, Poland, USA,
 After retiring worked in Egypt
WHAT IS GLASS
 Glass is not a solid.
 Glass is a supercooled liquid.
 A brittle transparent solid with irregular
atomic structure.
 A container for holding liquids while
drinking.
COMPOSITION OF GLASS
 Normal window glass .... Soda Lime
70% SiO2 ....... Sand
20% Na2CO3 .....Soda Ash
10% Ca2Co3 ......Lime
 Lead Glass contains 20% PbO ....Lead oxide
 Borosilicate contains at least5% Boric Oxide
ORIGINS OF GLASS
 What is a Fulgerite
 A naturally occurring form of glass
 Created when lightening strikes the desert
ORIGINS OF GLASS
FULGERITE SAMPLES
FULGERITE SAMPLES
OBSIDIAN
Another form of natural glass
 Obsidian is formed by volcanic activity
 Felsic lava extruded from a volcano cools
rapidly with minimum crystal growth
 Felsic substances are high in silica
OBSIDIAN
 Because of this lack of crystal structure,
obsidian blade edges can reach almost
molecular thinness, leading to its
ancient use as projectile points and
blades, and its modern use as surgical
scalpel blades
OBSIDIAN
OBSIDIAN
 Mammoth Lakes in California has an
obsidian dome
 At considerable personal expense I have
obtained some samples of obsidian
 So each of these samples cost me £1000 !!!
OBSIDIAN
OBSIDIAN
 Now here are some holiday photos
OBSIDIAN
 Now this sample was too big !!!
ORIGINS OF GLASS MANUFACTURE
 No one knows exactly when or where glass was first
made.
 Glass appears to have been produced as far back as the
second millennium BC by the Egyptians or the
Phoenicians.
 The Egyptians used a method called core-forming. A
shaped core was made of clay and dung, then molten
glass was wrapped around it and shaped by rolling it
on a smooth surface.
ORIGINS OF GLASS MANUFACTURE
Early Roman Glass Samples
ORIGINS OF GLASS MANUFACTURE
Early Roman Glass
Samples Mid 4th Century
NEXT STAGE
 Around the end of the 1st century BC, a new method,
glass blowing revolutionised glass production.
DECORATIVE GLASS MURANO
 MURANO glassmakers banished to the island in 1291
 By the 14th century, glassmakers were allowed to wear
swords and enjoyed immunity from prosecution.
 By the end of the 16th century, three thousand of
Murano island's seven thousand inhabitants were
involved in some way in the glassmaking industry.
DECORATIVE GLASS
ORIGINS OF FLAT GLASS MANUFACTURE
 Bulls Eye or Crown method
 Blow…….split…….. spin
CYLINDER BLOWN MANUFACTURE
Blown as large cylinder 1825
Swung over a pit
Laid on a table and split
CYLINDER PRODUCTION
CAST METHOD
 The molten glass was poured onto a special table and
rolled out flat.
 After cooling, the plate glass was ground on large
round tables by means of rotating cast iron discs
 The result of this "plate pouring" process was flat glass
with good optical transmission qualities.
 When coated on one side with a reflective, low melting
metal, high-quality mirrors could be produced.
CAST METHOD
FLAT DRAWN PROCESS
 The Pittsburgh Process,
invented by PPG in the
1920’s, involves drawing
a continuous sheet of
molten glass from a tank
vertically up a four-story
forming-and-cooling
tower
ROLLED PLATE
 Continuous production furnace
 Passed through water cooled rollers
 Cut into plates
 Sent to another factory
 Ground and polished
 Continuous grinding & polishing.
ROLLED PLATE
MODERN GLASS MAKING
Window
Glass
TYPICAL GLASS COMPOSITION
BODY TINTED GLASS
GREEN GLASS
IRON OXIDE
GREY GLASS
COBALT OXIDE
BRONZE GLASS
SELENIUM OXIDE
BLUE GLASS
COBALT OXIDE MORE
MODERN GLASS MAKING
 Raw materials mixed to give homogeneous mix
 Fed into a regenerative furnace with “cullet”
 Heated to 1550 centigrade
 Stirred to ensure perfect mix
 Cooled to about 11oo and poured onto molten tin
 Gradually cooled to about 900 and into annealing
lehr
 Cooled to room temperature and cut and snapped
MODERN GLASS LINE
GLASSMAKING
Inside a
Furnace
GLASSMAKING
Warehouse
View
GLASSMAKING
 Cold End of the Line
GLASSMAKING
 Cold End of the Line
USES OF GLASS
Window Glass
Automotive Screens
Specialist Coated Products
Aircraft Glass
LIBYA IN THE NEWS
Lockerbie bombing
Dec 21st 1988
Laminated windscreen
Specialised glasses
 Pan Am drops from 30,000 feet over Lockerbie
 Windscreen intact
 Cannot use as an advert
SHORT VIDEO OF FLOAT GLASS
Pilkington short film
Shown as part of guided tours
Filmed in various locations
Any questions?