Download - GLASS MAKING THROUGH THE AGES
Martin McBrideCarterton U3A
ORIGINS OF GLASSDECORATIVE GLASS MAKINGEARLY FLAT GLASS MANUFACTUREMODERN GLASS PRODUCTION
WHO AM I … WHAT DO I KNOW ABOUT GLASSApplied Chemistry Specialised in Glass
Technology and Fuel TechnologyOne 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 GLASSGlass 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 GLASSNormal window glass .... Soda Lime
70% SiO2 ....... Sand20% Na2CO3 .....Soda Ash10% Ca2Co3 ......Lime
Lead Glass contains 20% PbO ....Lead oxide
Borosilicate contains at least5% Boric Oxide
ORIGINS OF GLASSWhat is a Fulgerite
A naturally occurring form of glass
Created when lightening strikes the desert
ORIGINS OF GLASS
FULGERITE SAMPLES
FULGERITE SAMPLES
OBSIDIAN
Obsidian is formed by volcanic activity
Felsic lava extruded from a volcano cools rapidly with minimum crystal growth
Felsic substances are high in silica
Another form of natural glass
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
OBSIDIANMammoth 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
OBSIDIANNow here are some holiday photos
OBSIDIANNow this sample was too big !!!
ORIGINS OF GLASS MANUFACTURENo 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 MANUFACTUREEarly 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 MANUFACTUREBulls Eye or Crown methodBlow…….split…….. spin
CYLINDER BLOWN MANUFACTURE
Blown as large cylinder 1825Swung over a pitLaid on a table and split
CYLINDER PRODUCTION
CAST METHODThe 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 PROCESSThe 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 PLATEContinuous production furnacePassed through water cooled rollers
Cut into platesSent to another factoryGround and polishedContinuous grinding & polishing.
ROLLED PLATE
MODERN GLASS MAKINGWindow Glass
TYPICAL GLASS COMPOSITIONBODY TINTED GLASS
GREEN GLASS IRON OXIDE
GREY GLASS COBALT OXIDE
BRONZE GLASS SELENIUM OXIDE
BLUE GLASS COBALT OXIDE MORE
MODERN GLASS MAKINGRaw materials mixed to give homogeneous mixFed into a regenerative furnace with “cullet”Heated to 1550 centigradeStirred to ensure perfect mixCooled to about 11oo and poured onto molten tinGradually cooled to about 900 and into annealing
lehrCooled 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 GLASSWindow GlassAutomotive ScreensSpecialist Coated Products
Aircraft Glass
LIBYA IN THE NEWS
Lockerbie bombingDec 21st 1988Laminated windscreen
Specialised glassesPan Am drops from 30,000 feet over LockerbieWindscreen intactCannot use as an advert
SHORT VIDEO OF FLOAT GLASSPilkington short filmShown as part of guided tours
Filmed in various locations
Any questions?