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Glass - Materials

History and Production of Glass

How is natural glass formed? When certain rocks melt at extremely high temperatures, and then cool very quickly not allowing the liquid to crystallize.
What are some examples of events that can create natural glass? Volcanic eruptions, lightning striking sand, and meteors hitting the earth.
What is obsidian? Volcanic glass; it is shiny, black, and translucent
What are fulgurites? When lightening strikes the sand and forms glass.
When was the first glass produced? 5000-3500 BC; Phoenicians discovered glass while cooking sand with Natron blocks
When and where were decorative mirrors introduced? India in 600 BC
Glass making rose and fell with what Empire? The Roman Empire
In the 1200s glass furnaces were being built in England for what reason? For windows and vessels
Where was high quality glass being made in 1550? Venice
What two things made optical glass a necessity? Invention of spectacles in 1280 and the printing press in 1448.
What were the first two types of glass to be used for optical glass? Flint and Crown
Crown glass is made without ____ or ____ and originally used for window panes. Lead or iron
Flint is pure lustrous glass made with....? increased lead content
During the 1800's, glasses were worn inconsistently because they were a sign of..? Old age and weakness
Who founded Bausch and Lomb? Two German immigrants in Rochester, NY; John Jacob Bausch, a trained optician and Henry Lomb his financier and partner.
What are the dates for World War I and why is it important? July 28, 1914 and lasted until November 11, 1918; accelerated the development of glass manufacture technology.
Who founded the Corning Glass Company? Amory Houghton in 1851
Dr. S. Donald Stookey of Corning Glass Company is known for what optical development? photochromatic lenses
Who founded Pittsburg Plate Glass? Captain John B. Ford and John Pitcairn
What is the Pittsburg Plate Glass company known for? For the "plate process" which produced thinner lenses and for patening CR-39 Plastic
Who founded Schott Glass Technologies? Otto Schott, Ernst Abbe, and Carl and Roderich Zeiss
What developments are the Schott Glass Technologies known for? Scientific basis for specialized glasses; use of optical glasses in aerospace applications; pictures and videos of the first man on the moon using their technology; light weight eyeglass lenses
What is the name of the true inventor of eyeglasses? It is unknown, lost in obscurity.
Who invented the printing press and when? Johann Gutenberg in 1448
Why is the printing press important to the birth of optical lenses? As reading grew in popularity, people (specifically presbyopes) needed help seeing to read.
Why is Galileo important to the birth of optical lenses? Galileo created telescopes with higher power magnification, which created a need for better optics.
Define glass... A hard, brittle substance, typically transparent or translucent, made by fusing sand with soda, lime, and sometimes other ingredients.
Glass is a liquid or solid? It is an amorphous solid with no long-range molecular order.
Is glass regular in the arrangement of its molecular constituents? No, it has no regularity
Does glass flow when it is subjected to moderate forces? No
Is glass crystalline or non-crystalline? Non-crystalline
What is an amorphous solid? Solid material that is obtained by cooling without crystallization.
What are the three key ingredients of glass? Sand (Silica); Soda (Sodium Carbonate); Lime
What is the batch process? Ingredients are mixed while in a powder form and melted in a furnace.
What is used to contain the mixture within the furnace because it resists corrosion, can withstand high temps, and is free of iron oxide? Clay
What is cullet? What does it do to help resist corrosion? Recycled broken or waste glass used in glassmaking. Adds a glaze to the pot.
After cullet and any other ingredients are added to the mixture, the temperature is raised to ____ degrees Celsius? 1400 (2552 degrees Fahrenheit)
What is the fining process? The escaping of gas within the glass making process
Why is the fining process important? Allows bubbles to escape; impurities rise to the surface and is skimmed off
During the fining process, glass is stirred continuously with clay rods to produce a __________ mixture. homogenous
After melting, fining, and stirring the molten glass has the consistency of...? Syrup
Glass is cooled to ____ degrees Celsius and poured into sheets of varying thickness? 1200 (2192 degrees Fahrenheit)
Where are the sheets placed to allow them to cool to room temperature? An annealing oven
Why is the annealing process important? It reduces the strain on the glass
What happens after the annealing process? The sheets are cut into small pieces, reheated, and pressed or molded into rough blanks.
Which process is used more frequently today the batch process or the continuous flow process? Continuous flow process
What is the batch process used for today? special orders such as high-index lenses and colored glasses
How is the continuous flow process different from the batch process? Automated; used for large quantities; moten glass is extruded and pressed into molds instead of poured into sheets
What are desirable optical glass characteristics? The correct index of refraction and chromatic dispersion values; freedom from color; high degree of transparency; high degree of chemical and physical stability.
Thinner lenses with a higher index of refraction will bend light more or less? More because it slows light down more.
What is chromatic aberration? Color distortion in an image produced by a lens, caused by the inability of the lens to bring the various colors of light ot focus at a single point.
What are undesirable characteristics of optical glass? Striae - streaks or lines in the glass caused by uneven mixing; Bubbles - formed during melting and fining process; Inclusions - stones and crystallites, undissolved particles; Cloudiness
Improper annealing results in... Index differences; double refraction; and residual stress
Where was oldest glass lens found? In the ruins of Ninevah
Which Roman tragedian is known for reading all the books in Rome through a glass globe filled with water around 4 BC? Seneca
Created by: griffiskr