How Is Glass Made?

Before humans learned the secret of glassmaking, nature was the world’s only glassmaker.

Lightning striking sand melted it into long, thin tubes of glass, and volcanoes erupting melted rocks and sand into glass.

The earliest glass made by humans was probably a glaze on ceramic pottery made somewhere around 3000 B.C.

Today, three inexpensive ingredients, sand, soda ash, and lime, are melted together to make glass. This is done in large furnaces at high temperatures until the mixture become a syrupy mass. When this syrup cools, it is glass.

When glass is in a melted state, it can be shaped by many methods, but the most common are blowing, pressing, and drawing.

Blowing is the oldest method of working with glass, dating back thousands of years. A ball of molten, or melted, glass is put on the end of a hollow iron pipe, and a worker blows gentle into the pipe (much like the way you blow soap bubbles) until the glass takes the shape and thinness the blower wants.

During this process, the glass is constantly reheated to keep it soft and workable.

When the glass is shaped to the blower’s satisfaction into a bottle or a vase, it is broken from the pipe. Although glass blowing by hand is still done today, it can also be done by machine.

In the pressing method, a hot glob of glass is dropped into a mold, then pressed with a tool, so the glass fills the inside of the mold. Ashrays, baking dishes, and glass containers are made this way.

The drawing method shapes glass flat, as for windows and mirrors, or into tubes, as for fluorescent lights, TV tubes, and laboratory equipment. To make flat glass, first the melted glass is drawn into a tank of melted tin. The tin’s perfectly smooth surface forms a smooth layer of glass as the glass floats on top of the tin.

To make glass tubing, a stream of molten glass is drawn around the inside of a cylinder. As the cylinder rotates, air is blown through it, forming a continuous tube out of the glass.

No matter which method is used, the glass must still go through a process called annealing. In annealing, the glass is reheated and gradually cooled to restore its strength and prevent its shattering.

Tempering is also used to strengthen glass. In tempering, the glass is reheated, then chilled by sudden blasts of cold air.

This process should not be confused with another method called lamp working, in which finished glass tubes are heated over a blowtorch, and as the glass worker bends, twists, and stretches the glass, he can create miniature animals, ships, and baskets.

Banks, tanks, aircraft, and some government cars have glass so thick and with so many layers that it can stop a bullet even at close range.

Comments

  1. Anonymous says

    This was good information, but I was also looking for specifics. Good insight on the history and the three common methods of glass though!!

  2. Anonymous says

    I wondering why when you named the 3 most common methods and put a paragraph for each one you didnt put one for pressing?

  3. Leslie Martinez says

    Me I am doing this report and I was wondering if you put alittle more infomation ABOUT NOT how to make it.Also if you can tell me who invented glass,when was it invented,where was it invented,why was glass invented and HOW was glass invented?

  4. Anonymous says

    Nice simple language for my year 9 class to find out how glass is made – very good.

  5. Anonymous says

    i got alot of info.
    this is all i needed for my science fair project.
    can i get how fibreglass is made?

  6. Anonymous says

    Everbody looks like ants from here!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  7. amanomis says

    OMG I HEARD THE FUNNIEST JOKE….
    y is 2×2=4?because 5 is already used!!!!!!!!!!! o wait did i mention that he was A COW?

  8. ashwin says

    Me I am doing this report and I was wondering if you put alittle more infomation ABOUT NOT how to make it.Also if you can tell me who invented glass,when was it invented,where was it invented,why was glass invented and HOW was glass invented?………..sri_1Nonly1

  9. Anonymous says

    On my homework,I have to give the website and author of the article I got my information from.So, if there were an author this would have helped me a lot.

  10. olive says

    hi can enyone plz tell me wat it is made of cuz i am doing this thing for school so i wounld be thanked if ues could tell me

  11. olive says

    hi i am doing the a simapa thng to you so maybe we can help each other out

  12. ke$ha says

    Lady gagaz a shim like me :)
    r u all nerdz 8) nerd r freakin retartz!!!!

  13. ke$ha says

    y the hell am i a FREAKIN!! BOX!!!!!!:( I’m grumy now coze I’m a FREAKIN BOX!

  14. Lana says

    Some people a really weird ^^^^
    Thanks! it was pretty helpful but i was wondering if you could write some more information on the history of glass making, and the industry :)
    thanks

  15. kai says

    I had to do some homework about glass i have got allot down on my paper.

  16. Maria says

    Hey thanks i love u guys. This helped me a lot on my science project. :D

  17. Katie Prime says

    Really?! I have a project on glass too! I love glass.. We could be glass buddies! Please say yes I have no other friends :) Lots of love, Katie :) X X X

  18. Ginosko says

    Hi Katie,

    I developed the love for glasses do you mind sharing your knowledge with me?

  19. DarkAceKirby says

    Well, that saved me from being completely clueless for a topic on a science project. Thanks, and SUBSCRIBE!!!

  20. jeni says

    omg this is going to make my A in science to an A+! i am so happy for that cause my mom would kill me if I got an A- on anything! : (

  21. edward says

    thank you this information helped me my grade is A+ on Science yeeeeeeeaaaaaah!

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