GLASS MAKING THROUGH THE AGES

1. GLASS MAKING THROUGH THE AGES Martin McBride Carterton U3A

2. GLASS MAKING THROUGH THE AGES ORIGINS OF GLASS DECORATIVE GLASS MAKING EARLY FLAT GLASS MANUFACTURE MODERN GLASS PRODUCTION

3. 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

4. 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.

5. COMPOSITION OF GLASS • Normal window glass .... Soda Lime70% SiO2 ....... Sand20% Na2CO3 .....Soda Ash10% Ca2Co3 ......Lime • Lead Glass contains 20% PbO ....Lead oxide • Borosilicate contains at least5% Boric Oxide

6. ORIGINS OF GLASS • What is a Fulgerite • A naturally occurring form of glass • Created when lightening strikes the desert

7. ORIGINS OF GLASS

8. FULGERITE SAMPLES

9. FULGERITE SAMPLES

10. 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

11. 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

12. OBSIDIAN

13. 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 !!!

14. OBSIDIAN

15. OBSIDIAN • Now here are some holiday photos

16. OBSIDIAN • Now this sample was too big !!!

17. 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.

18. ORIGINS OF GLASS MANUFACTURE Early Roman Glass Samples

19. ORIGINS OF GLASS MANUFACTURE Early Roman Glass Samples Mid 4th Century

20. NEXT STAGE • Around the end of the 1st century BC, a new method, glass blowing revolutionised glass production.

21. 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.

22. DECORATIVE GLASS

23. ORIGINS OF FLAT GLASS MANUFACTURE • Bulls Eye or Crown method • Blow…….split…….. spin

24. CYLINDER BLOWN MANUFACTURE • Blown as large cylinder 1825 • Swung over a pit • Laid on a table and split

25. CYLINDER PRODUCTION

26. 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.

27. CAST METHOD

28. 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

29. ROLLED PLATE • Continuous production furnace • Passed through water cooled rollers • Cut into plates • Sent to another factory • Ground and polished • Continuous grinding & polishing.

30. ROLLED PLATE

31. MODERN GLASS MAKING • Window Glass

32. TYPICAL GLASS COMPOSITION BODY TINTED GLASS GREEN GLASS IRON OXIDE GREY GLASS COBALT OXIDE BRONZE GLASS SELENIUM OXIDE BLUE GLASS COBALT OXIDE MORE

33. 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

35. MODERN GLASS LINE

36. GLASSMAKING • Inside a Furnace

37. GLASSMAKING • Warehouse View

38. GLASSMAKING • Cold End of the Line

39. GLASSMAKING • Cold End of the Line

40. USES OF GLASS • Window Glass • Automotive Screens • Specialist Coated Products • Aircraft Glass

41. LIBYA IN THE NEWS • Lockerbie bombing • Dec 21st 1988 • Laminated windscreen

42. Specialised glasses • Pan Am drops from 30,000 feet over Lockerbie • Windscreen intact • Cannot use as an advert

43. SHORT VIDEO OF FLOAT GLASS • Pilkington short film • Shown as part of guided tours • Filmed in various locations

45. GLASS MAKING THROUGH THE AGES Any questions?