martin mcbride carterton u3a. origins of glass decorative glass making early flat glass manufacture...

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?