Clay (L16)

Question 1

What are the 3 ways clay can be referred to?

Answer 1

1. a type of mineral
2. sediment grain size
3. a mass of minerals that behave plastically when wet

Question 2

What is a ceramic?

Answer 2

a hard, brittle, nonmetallic material made from clay and other Earth materials and hardened by firing at high temperature

Question 3

what kind of structure does a ceramic have?

Answer 3

a crystalline structure

Question 4

what are the basic building blocks of clay?

Answer 4

1. sheets of linked silica tetrahedra
2. sheets of linked alumina octohedra

3.assorted positively charged ions that bond these sheets together

Question 5

2 common clay minerals?

Answer 5

kaolinite and llite

Question 6

what is the main property that makes clay an amazing medium in art applications?

Answer 6

the shape of its crystals

Question 7

Clay mineral crystals have a ____ cleavage in ____ direction

Answer 7

perfect, one

Question 8

what does it mean for clay mineral grains to be wide and flat?

Answer 8

means that under weak stress, when it is being deformed, the plates can slide past one another, allowing the mass of clay to deform very easily

Question 9

what makes clay so cohesive?

Answer 9

the high surface area of the mineral grains

Question 10

clay minerals can be produced from the weathering of which mineral?

Answer 10

fledspar minerals

Question 11

the 2 ways we loosely categorize clay into?

Answer 11

primary clays - found in original site of formation (contain kalolinite)

secondary clays - transported form original site of formation (contain kaolinite but as well as other minerals)

Question 12

what is the body of blended clay called?

Answer 12

clay body

Question 13

what are the 3 ways clay bodies can be categorized into?

Answer 13

Earthenware, stoneware, and porcelain

Question 14

what is grog and what does it do?

Answer 14

a low-porosity material that are added to some claybodies which retains heat and adds a rustic appearance, adds strength to clay, and reduces the overall shrinkage rate

Question 15

What is earthenware?

Answer 15

composed largley of secondary clays

cheapest type of clay body (creates mugs, plates, flowerpots)

Question 16

what is an advantage of using earthenware for flowerpots?

Answer 16

earthenware is porous and permeable so can allow air and water to move through the walls of the pot

Question 17

what is stoneware?

Answer 17

made mostly from primary clays and used to make items that are harder and stronger than earthenware

impermeabel to water so used to make floor tiles and drainage pipes

Question 18

What is porcelain?

Answer 18

“upper-class” category of ceramic made from primary clays

finest texture of all of the ceramics, great strength (used for thin objects, such as fine dinnerware) and transluscent

Question 19

how can porcelain have such smooth surfaces?

Answer 19

doesnt use grog

Question 20

what are the 3 main methods of producing a ceramic piece?

Answer 20

Handbuilding
Throwing
Slip-casting

Question 21

What is handbuilding?

Answer 21

forming an item in a freeform manner without a potter’s wheel

Question 22

What is Throwing?

Answer 22

clay that is shaped on a spinning potters wheel

Question 23

What is slipcasting?

Answer 23

clay that is made by producing a cast inside a mould

Question 24

What is the process of creating a ceramic?

Answer 24

1. Shaping
2. Air-drying
3. Firing: Kiln Drying
4. Glazing

Question 25

What must be done during the Air-drying process?

Answer 25

a ceramic piece must be air-dried to a “greenware” state before it is fired

Question 26

What happens during Kiln Drying

Answer 26

complete drying happens here and elimination of all of the free water only happens when the boiling point of water has been reached

Question 27

What happens during the major transformations of the clay?

Answer 27

the clay loses its hydrogen and oxygen as water and the remaining material produces mullite and quartz

Question 28

what is mullite?

Answer 28

an aluminim silicate mineral that laces the structure together, giving it cohesion and strength

Question 29

what happens when the ceramic is finally cooled?

Answer 29

the mullite crystals interlock and become glass to bind the whole structure together

Question 30

At what point in temperature does Primary clay and Secondary clay vitrifiy in?

Answer 30

primary clays - high temp
secondary clays - lower temps

Question 31

what do you call a ceramic that has been fired in a kiln but has not yet been glazed?

Answer 31

“bisqueware”

Question 32

What is glaze?

Answer 32

a form of glass consisting of glass-forming minerals, and gives the ceramic its beauty in color and finish and waterproof

Question 33

what are 2 common additives used to increase the opacity of glazes?

Answer 33

titanium oxide and tin oxide