Glossary of Ceramics I

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What is the purpose of flux in glazes?
Flux allows glassformers to melt, and influences surface texture and color.
What are some glassformers listed as ingredients in our glazes?
Silica (Si02/Flint) and Boron as bases, Arsenic and Phosphorus as additives.
What is used as a stabilizer in our glazes?
Alumina (Al2 03)
What does a stabilizer do in a glaze?
Stabilizers affect the mixture's viscosity.
What is viscosity?
The tendency of a liquid to resist flow.
What are some fluxes found in glazes?
Feldspar, Fritt, Talc (Mg CO3), Whiting (C2 C03), Dolomite (Mg Ca CO3), Wolastonite (C2 Si O2)
Fritt does what as a flux?
Fritt makes ingredients less soluble and makes toxic materials like lead safer to use.
Talc, Whiting, Dolomite, and Wolastonite contain natural fluxes, such as?
sodium, potassium, calcium, magnesium, barium, lithium, zinc, strontium, lead
Some colorants in glazes are...
iron (many colors, brown), chrome (green), copper (green), cobalt (blue), manganese (grey-brown), nickel (grey-brown), vanadium (yellow),uranium
What are some influences on the color of glazes?
percentage of colorant to other ingredients, atmosphere in the kiln, temperature fired, flux
What is reduction?
a reduction in the amount of oxygen in the kiln- physically alters glaze, coloring, etc.
What are some opacifiers and what do they do?
Tin, zirconium, and titanium all make glazes white and opaque.
What kind of glaze did we use on stoneware projects?
cone 9- high temperature
What 4 categories of ingredients make up a glaze?
glassformer, stabilizer, flux, colorant
What is clay made of?
decomposed igneous rock
What is primary source clay?
it is found near the rock it came from, and is thus coarser and more pure.
What is secondary source clay?
found far from its source, this clay is broken into fine particles. has lots of impurities.
what is the shape of a clay particle?
clay particles are flat hexagonal shapes that slide against eachother. they are in clumps in coarser clay.
How does clay become more plastic?
natural agents like mold and bacteria break down clay and make it aged and plastic. water forms a slippery film between plates.
criteria to choose clay by include...
color, temperature required, plasticity
pure clay is what color?
what is the chemical formula of pure clay?
Al2 O3 2S1 O2 2H20 (or, alumina-silica-water)
the clay we use is made of what 3 categories of ingredients?
Clay (duh), filler, and flux
What are some clay types, in order of higher temps/coarser to lower temps/finer?
Kaolin, fire clay, stoneware, call clay, earthenware, bentonite
what are some fillers in clay?
grog, sand, flint
what are some fluxes in clay?
feldspar, talc, fritt
what is meant by "vitreous"?
water-tight, having a hard, glassy surface
what is meant by "refractory?"
material that can withstand high heat, like clay!
What is grog?
ground up fired clay
what do fillers do?
adds strength, reduces shrinkage, adds hard, non-plastic particles.
about feldspar:
for high temps, a natural decomposed igneous rock.
about talc:
magnesium silicate, in earthenware
about fritt:
man made. carefully chosen ingredients to control necessary temperature. ground up glassy material.
When/where/what were the earliest known glazes?
c. 5000 BC, in Mesopotamia and Egypt- Sodash and Borax (water soluble). Egypt had a turquoise paste.
Early firing was done in_______. What problems did this cause? why?
pitfires. made unstable, pourous pieces, due to lack of high temp
following pitfires, ceramicists invented an_________ system for more durable pieces
after updraft firing came_______. when/where?
downdraft kiln. Hunn dynasty in china, 200 BC. used wood ash, limestone, feldspar as glazes.
about porcelain:
kaolin, feldspar, limestone. originated in china.

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