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Glass - Materials
History and Production of Glass
| Question | Answer |
|---|---|
| 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
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