Ceramics Artwork Fall 2008

Fall 2008, 001

Fall 2008, 002

Fall 2008, 003

Fall 20080, 004

Fall 2008, 005

This 5 pieces is part of a series of 16.
Series Fall in Provo 2008

Cone Firing Numbers

In standard firing, cones of the right number are placed around the kiln and are watched. When the cones fall the kiln is turned off. This works the same for gas and electric kilns.
Automatic electric kilns such as the Skutt Kilnmaster series have a thermocouple which continuously measures the temperature, records it over time, and shuts off when the appropriate heat absorption has been met. So if the ramping temperature is fast, the kiln will go to a higher temperature before it turns off than if the ramping temperature is slow (thus allowing the clay to absorb more heat along the way.) The final temperature is most affected by the rate of temperature increase over the last 300 to 400 degrees of firing.

Think of the 0 in a cone number as meaning "minus". So 06 is much cooler than 6 because it is like a "minus 6".


Cone /Orton Cones / Orton Cones /Orton Cones
number /Final temp in / Final temp in /Final temp
/ /degrees F at / degrees F at /in degrees F at
/ /ramp rate of / ramp rate of / ramp rate of
/ /27 degrees F/hr /108 degrees F/hr /270 degrees F/hr

10 /2284 / 2345 / 2381
9 / 2235 / 2300 / 2336
8 /2212 /2273 /2320
7 /2194 /2262 /2295
6 /2165 /2232 /2269
5 /2118 /2167 /2205
4 /2086 /2142 /2161
3 /2039 /2106 /2138
2 /2034 /2088 /2127
1 /2028 /2079 /2109
01 /1999/ 2046/ 2080
02 /1972/ 2016/ 2052
03 /1960/ 1987/ 2019
04 /1915/ 1945/ 1971
05 /1870/ 1888/ 1911
06 /1798/ 1828/ 1855
07 /1764/ 1789/ 1809
08 /1692/ 1728/ 1753
09 /1665/ 1688/ 1706
010 /1636 /1657/ 1679
011 /1575 /1607/ 1641
012 /1549 /1582/ 1620
013 /1485 /1539/ 1582
014 /1395 /1485 /1540
015 /1382 /1456 /1504
016 /1368 /1422 /1465
017 /1301 /1360 /1405
018 /1267 /1252 /1283
019 /1213 /1252 /1283
020 / /1159/ 1180
021 / / 1112/ 1143
022 / /1087/ 1094

Temperature conversion

Temperature conversions between the three temperature scales:

kelvin / degree Celsius conversions (exact):

kelvins = degrees Celsius + 273.15
degrees Celsius = kelvins - 273.15


degree Fahrenheit / degree Celsius conversions (exact):

degrees F = (degrees C x 9/5)+ 32
degrees C = (degrees F - 32) x 5/9

or
go to Convertor
http://chemistry.about.com/library/weekly/bltempconvert.htm

BODY REDUCTION VS GLAZE REDUCTION

Glaze reduction can take place at 1900 F to 2400 F
Body reduction can take place at 900 F to 1300 F

Below is a list of the common oxides used in glazes.

NAME / COMMON NAME/ CATEGORY / ABBREVIATION
Silicon Dioxide/ Silica/ Glass Former/ SiO2
Aluminium Oxide/ Alumina/ Stabiliser/ Al2O3
Boric Oxide/ Glass/ Former, Stabiliser, Flux/ B2O3
Barium Oxide/ Baria/ Flux/ BaO
Calcium Oxide/ Calcia/ Flux/ CaO
Potassium Oxide/ Potash/ Flux/ K2O
Sodium Oxide/ Soda Flux/ Na2O
Lithium Oxide/ Lithia/ Flux / Li2O
Magnesium Oxide/ Magnesia Flux/ MgO
Lead Oxide/ Litharge/ Flux/ PbO
Strontium Oxide/ Flux/ SrO
Zinc Oxide/ Flux/ ZnO2
Stannous Oxide Tin/ Opacifier/ SnO2
Titanium Dioxide/ Anatase/ Opacifier/ TiO2
Zirconium Oxide/ Zirconia/ Opacifier/ ZrO2
Copper Oxide/ Colorant/ CuO
Copper Carbonate/ Colorant/ CuCo3
Cobalt Oxide/ Colorant/ CoO
Cobalt Carbonate/ Colorant/ CoCO3
Manganese Dioxide/ Colorant/ MnO2
Iron Oxide (red)/ Colorant/ Fe2O3
Rutile/ Colorant/ TiO2
Vanadium Pentoxide/ Colorant/ V2O5
Nickel Oxide/ Colorant/ NiO

CLAY

Clay is made up of two major components, silicon dioxide and aluminum oxide. The formation process is due to the erosion of the earth’s surface. The erosion of the rock is caused by the weather, which wears down the rock into small microscopic particles. Clay can be classified into two types; residual clay that could be dug up from its original place, and the second type is the transported clay, which is also called the sedimentary clay that was remove from it original location through erosion.
Clay is form in three ways; by chemical decomposition of rocks, such as granite, containing silica and alumina; by solution of rocks, such as lime stone which contain clayed impurities being soluble are deposited as clay; lastly by the way of disintegration and solution of shale. (“Shale: sedimentary rock formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock. Shales comprise an estimated 55% of all sedimentary rocks. The composition of shale varies widely. Shales with very high silica content may have been formed when large quantities of diatoms and volcanic ash were present in the original sediment. Large numbers of fossils in shales may give them a high calcium content; such shales may grade into limestones. Shales that contain a large percentage of alumina are used as a source of that mineral in the manufacture of cement. Shales containing abundant carbonaceous matter grade into bituminous coal. Oil shales are widely distributed in the W United States and may be a future source of petroleum.”)
The Columbia Electronic Encyclopedia,

Evaporation of all the water by firing to the temperature of 500 degree could remove all water content that had been trap and cannot be evaporated below 350 degrees. At this stage the molecules of the clay would collapse together and fill up the gaps between the spaces. This would give the clay hardness and strength. The process is called vitrification. At this stage the clay cannot return to it clay form or absorb water.