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The Rock cycle

http://www.geologycafe.com/class/chapter2.html2

Earthernware

Usually higher Iron content.Fired at a lower temperature(1000-1150C)

Firing earthernwarelow fire: 1000-1150C

Does not vitrify: remains somewhat porous (unlike porcelain, which is very hard and non porous)

FiringTemperature (C)Event[clay]-O-[clay] + H2O(g)

Sulphurous, Carbonaceous and any other organic material burn off800-900Sintering: clay particles begin to fuse together to form crystals1000-1150Maturation of earthernware

SinteringModel of the interparticle bond as the ceramic microstructure istransformed during the sintering process.Loose powder (start of bondgrowth).Initial stage (the pore volume shrinks).Intermediate stage (grain boundaries form at the contacts).Final stage (pores become smoother).

1080C1200C

http://www.scielo.br/scielo.php?pid=S1516-14392005000200020&script=sci_arttextThe ceramic paste was formed from a mixture of red kaolinitic clay from Campos-RJ, a calcareous from Italva-RJ and commercial quartz. The composition of the mix used was as follows: red clay 70 wt. (%), calcareous 15 wt. (%) and quartz 15 wt. (%)9.The fractured surfaces of the specimens sintered at 1080 and 1200 C are shown inFigure 5. At 1080 C (Figure 5a) the microstructure reveals regions that contain large pores, resulting from carbonate decomposition. These regions are connected with dense zones. At 1200 C the open porosity decreases. Some glassy phase also begins to emerge.

Figure 7 represents a model of sintering process, the starting point is consisting of contacting particles, the initial bonds range from point contacts to highly deformed interfaces.With sintering the contacts grow in size, and in the initial stage there is extensive loss of surface area.As the pore structure becomes rounded the discrete particles are less evident and the intermediate stage of sintering occurs.This is characterized by a tubular, rounded pore structure that is open to the compact surface; gas can permeate through the open pore space.Consequently, many sintered structures are sintered to this stage only to preserve desirably pore structures [21].

http://www.azom.com/article.aspx?ArticleID=33655

Firing

Temperature (C)Event1000-1150Maturation of earthernware1100-1200Glass forming occurs: kaolin changes its form to mullite and cristobalite -> silica forms glue that fills up the the pores between the clay>1200-1300Maturation of stoneware (vitrified)>1300 to 1400Maturation of porcelain (vitrified)

cristobalite

mulliteAcicular mullite crystals with short-prismatic indialite

Quartz has two polymorphs. Alpha quartz is trigonal and stable below 573 C. Above 573 C thermal agitation becomes vigorous enough to overcome the slight skewness of the chains and the structure inverts to beta quartz, which is hexagonal. The transformation involves no atomic rearrangement, and all quartz at surface conditions is alpha quartz.6

Test draw / draw trialsSmall pieces of ceramic (same material as actual pieces)

Drawn out to check completion of firing by looking at their physical properties (glaze adhered properyl etc)

Pyrometric Cones

Cone numbers run downwards 022 -> 01,Then upwards 1 -> 14

Temperature sensitivity from approx 580CUp till 2000C,In steps of around 20C

-> cones will bend at specific temperature ranges-> each cone is a specific mix of feldspar, kaolin, and other minerals

Earthernware

FiringFiringReduction Firing:Limited supply of oxygenIncomplete combustion of fuel(usually begins 900-1000C)-> cause chemical reduction in certain metal ions e.g. FeO, iron (ii) oxide: blackOxidation firing:Adequate supply of oxygen-> cause oxidation in metal ions, e.g. Fe2O3 iron(iii) oxide: reddish brown

Porous clay?

Well, the metallic ions in the clay mixtureInteract with the tea to perhaps improve the taste

Kobiwako Side Handle Teapot

Lao Zi Ni Purple Clay "Xi Shi"

Qing Hui Ni Clay "Ju Lun"

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StonewareMaturing temperature approx 1200 -1300C Clay generally has a lower proportion of iron.

Opaque. Fully vitrified.

Ash glaze

Different floor, different effect -> lower floors has more ash

The pots will all have a different finish depending on where they are placed. On the top level it is possible to get a natural glaze, wheras pots placed in the bottom are covered with ash.

Bizen: Only the wood of the Japanese red pine is used for firing. Adding the wood slowly produces red and purplish tones from the gasses released by the burning wood. Adding the wood faster results in gray and black tones due to the deposition of ash on the piece or the carbonization of the clayYohen teapot: The artist achieved this finish by controlling the placement of the teapot in relation to the heat and flame inside of his kiln, and by covering the teapot in rice husks to attract the fame to leave signature marks.12

Ash from the wood or organic matter being burnt contains various metal ions -> sprayed onto the earthernware by the flames and fused onto them

-> various raw looking coloured glazes that can look very rugged

(earthernware)

Hokujos Mogake teapot13

Slip Glazing

Clay dispersed in water -> very fluid, often colourants are added (metal oxides/carbonates) -> used to the base clay with another tint/colour.

Glazing

Celadon glaze

Glazing

IngredientsGlass former form clear surface, e.g. Silica (in feldspar), can be topped upFlux - lower melting pointe.g. soda / potash (in feldspar)Stabiliser prevent flowing off during melting e.g. alumina (in feldspar)Colorant - (copper, iron, cobalt, etc. usually in oxide/carbonate form)

Pretty good reference on glaze chemistry:http://www.duncanshearer.co.nz/glaze/glazechemistry.html17

Feldspar rocks (silicates)

minerals of varying composition, many uses,e.g. making glazesContains alumina, silicates with a cation, in a macromolecular structure

Potash feldspar: mainly potassium feldsparSoda feldspar: mainly soda feldspar

And some others

Early Chinese porcelain (17th century) body sherd (left) and close up of paste (right).

The Chinese PorcelainIngredients:Very pure kaolin clay,Mixed with petunze (type of feldspar found in china)-> fully vitrified, strong extremely low porosity.

http://www.jefpat.org/diagnostic-old/Historic_Ceramic_Web_Page/Historic%20Ware%20Descriptions/porcelain_images.htm

Chinese porcelains have a clear, glossy feldspathic glaze that is usually fused to the paste. Vessels are bisque fired, then painted and glazed before being fired a second time.19

UnderglazePainted below a transparent/translucent glaze.The blue cobalt pigment is painted as an underglaze in porcelain,with a transparent feldspathic glaze above it.Fuses into the clay and glaze when fired

http://www.jefpat.org/diagnostic-old/Historic_Ceramic_Web_Page/Historic%20Ware%20Descriptions/porcelain_images.htm

Chinese porcelains have a clear, glossy feldspathic glaze that is usually fused to the paste. Vessels are bisque fired, then painted and glazed before being fired a second time.20

Overglaze / EnamelPainted on top of the (slip/feldsparthic) glaze.Fired at a lower temperature (approx 900C)-> Achieves a different range of surfacing and colour effects

http://www.jefpat.org/diagnostic-old/Historic_Ceramic_Web_Page/Historic%20Ware%20Descriptions/porcelain_images.htm

Chinese porcelains have a clear, glossy feldspathic glaze that is usually fused to the paste. Vessels are bisque fired, then painted and glazed before being fired a second time.21

Biscuit / Bisque FiringIt is an Initial firing: not to maturing temperature, but high enough to burn off all carbon-based material, and reduce fragility of ware -> easier to paint glazeApprox 900 to its arrangement of molecules is kind of random when zoomed in

More specifically, glass forms over a range of temperature (no fixed melting point) -> we call that glass transition

Transparency of glass

Because light in visible wavelengthsDo not have enough energy to excite the electrons in the molecules to a higher energy level.

So they just pass through.

If an atom was a football stadium, the nucleus would like a pea in the middle, and electron like a grain of sand on a spectators row.27

IngredientsGlass former: SilicaFlux (lowers melting point of silica to approx 1200C) : Sodium carbonate (soda)Stabiliser (strengthen structure of glass, keeps it insoluble): lime (calcium oxide), magnesium oxide, aluminium oxideModifiers: lead oxide, barium oxide, lanthanum oxide -> increase refractive index, boron oxide -> strengthen glass against thermal shock (borosilicate glass)Colourants: various kinds of transition metal oxides, e.g. iron oxide: green

If an atom was a football stadium, the nucleus would like a pea in the middle, and electron like a grain of sand on a spectators row.28

Green glass?

Due to presence of small amounts of iron(ii) oxide -> either contaminant, or added as a lubricant

Manganese dioxide (magenta/purple tint) added to neutralise green tint,But will really turn purple in UV light (sunlight) due to formation of manganate(VI) ion

FormingSheets: Rolled / Float glass

L'esprit de l'escalier, francois millet, manufactured by les ateliers loire

Blow molding

Mouth Blown

Blowing iron with glass, inside glory holeRolling on the marver (steel covered table surface)Shaping glass with jack (metal)

Shaping glass with block (wood)

optic mold: get certain shapes

Forming methodsHand formed

Bullet proof breath, christine borlandMade by jin won han

AnnealerOven that lets the glass cool at a slower rate: prevent cracks from forming

Corning museum of glasshttp://www.cmog.org/http://www.youtube.com/user/corningmuseumofglass/videos

Murano glasshttp://www.muranonet.com/

Metal castingBronze: an alloy - copper mixed with some other metal, usually tin, sometimes zinc (forms brass)

Lost wax casting

Wax sculptureGating channels added -> for molten bronze to flow into mold during casting

Investment -> building a ceramic shell around sculpture; dipped in clay slurry, then sand -> 9 cycles to build up wallWax is then melted away in an autoclave (high pressure steam chamber) or kiln, leaving a space

Mold heated to around 600C in a kiln Bronze melts at 900+ C, poured into mold

Devestment: mold smashed to reveal bronze inside

Metal chased:Cleaned, perhaps sandblasted, joints neatened

Metal given a patina, using various chemicals,

Typically some acid, or reducing or oxidising agent, with a metallic salt

Pile, Gavin Turk, painted bronze

Joel Morrison, stainless steel

Marble sculpting

The tools have remained the same since long time ago

Marble quarry

Metamorphic rock:

Limestone after much heat and pressure

If have impurities:Haematite: redLimonite: yellow

Rough chisel marks

Chisel draftFiguration

http://www.perfectsculptures.com/html-en/about-us-factory.htm#49

Fine SculptingPolishing

The Rape of Phorsephine, Bernini

The rape of proserpinaHades and persephone,Apollo and Daphne52

The Ecstasy of St Theresa, Bernini

Was marble always white?

Trojan archer from the Temple of Aphaia on Aegina, Greek, c. 490-480 B.C.Athena, from the same temple and of the same date. Research by german archaeologist Vinzenz Brinkmann ,Using UV-Vis absorption spectroscopy

Reconstruction has been restricted to areas whose original appearance may be determined with some certainty.

; German archaeologist Vinzenz Brinkmann is on a mission. Armed with high-intensity lamps, ultraviolet light, cameras, plaster casts and jars of costly powdered minerals, he has spent the past quarter century trying to revive the peacock glory that was Greece. He has dramatized his scholarly findings by creating full-scale plaster or marble copies hand-painted in the same mineral and organic pigments used by the ancients: green from malachite, blue from azurite, yellow and ocher from arsenic compounds, red from cinnabar, black from burned bone and vine.

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Woodworking

Not all woods are the same,And some are harder than others

OakWalnutMahoganyCherryBasswoodMaplePineAnd woods have different colours

Drying wood better stabilityRemove:Free wateris found in its liquid state in the cell cavities or lumens of wood.Bound waterthat is found as a part of the cell wall materials.

Air Drying

Sawing wood to planks

Plain sawn: Has the cathedral effect.

Quartersawn warp least

But, of course, if youre doing a 3D sculpture, you dont saw the wood

Its similar to marble sculpting

Paper?

Richard Sweeny

Hyperreal sculptures: fibreglass, silicone

Ron Mueck

Finally, back to some ceramics

TSANG Zhang-cheng