Labs
To get the air bubbles out
True or False: Bisque ware is clay that has been in the kiln and Bisque fired.
True
What type of glass is "volcanic glass"?
Obsidian
Rapidly cooling glass to make is stronger is called what?
Tempering
Glaze is a type of what?
Glass
Lightbulb Lab (see Wong PPT) - What is "A"
Filament
What does "workable" mean?
Clay is soft and flexible enough to shape without cracking, crumbling, or sticking too much. (You can shape it)
How much "lead" is in lead-alkali glass?
18-33%
In molten/melting glass; this indicates the resistance to "flow" that the glass material posesses.
Viscosity
What are (2) ways to make glass stronger?
Tempering & Chemical Strengthening
Your glass panels had to cool down slowly in the kiln. Glass that is cooled slowly has less __________.
[Fill in the blank]
When did Egyptians first start using glazed pottery.
4000 B.C.
(2) tetrahedra share what type of atom?
Oxygen
Quickly or rapidly cooling glass is called:
Quenching
Draw the (3) representations of silicate tetrahedron
(See Wong PPT)
How does glass get it's color. And provide (2) examples we used in our lab. (Chemical names or forumlas)
Color is caused by immpurities called oxides. Examples: Cobalt Oxide (CoO), Chromium Oxide (Cr2O3), Copper Oxide (CuO)
Silicon is the main ingredient in clay. What are the (3) metallic ions silicates frequently bond with?
Potassium, Magnesium, Aluminum
Why is glass amorphous?
It lacks a CRYSTALLINE STRUCTURE
This is when glass allows some light pass through, but objects cannot be clearly seen through it.
Translucent
How does a "Prince Rupert Drop" form?
Heated/Molten glass drops into cold water
Describe the (3) stages of clay (before it goes into the kiln for bisque firing)
1) Wet Clay: where wedging/initial shaping occur
2) Leather Hard: where you can still carve into the clay, but its not as shapeable
3) Bone Dry: Most of the water has been removed & it's brittle
Draw how clay particles sinter together.
See Wong slide
Describe the (3) steps in making tempered glass:
1) Glass is precut
2) Glass is heated to 150 degrees greater than the temperature which it starts acting like a solid when cooled (transition temperature)
3) Glass is bent/shaped.
This is when a glaze forms crystals instead of staying glassy, causing the surface to look cloudy or matte instead of smooth and shiny
Devitrification
Explain how "Reduction" takes place in the Raku process.
- Glaze has metal oxide in it
- Metallic ions in the oxide are reduced and become atoms
- Pottery is quenched to stop it from re-oxidizing/changing back when exposed to air (oxygen) again