Lab Quiz #3 - Ceramic Analysis Flashcards
Pottery
Objects made of baked (poorly-fired) clay
When did people begin making pottery?
About 20,000 years ago
The technology was invented several times throughout human history
What is pottery also known as?
Earthenware
Pottery is fired between how many degrees?
600 - 1200 degrees Celsius
What is ceramics also known as?
stoneware
Ceramics
Well-fired Clay
Ceramics are fired between how many degrees?
1100 - 1200 degrees celsius
Ceramic use was widespread in the Old World
about 8000 years ago
Ceramics was developed independently in the New World
4000 years ago in Ecuador and Colombia
What is the emergence of ceramics associated with?
shifting cultures and time periods
What we can learn - Diet
Chemical analysis of residues on the inside of vessels can indicate what was being stored and eaten
What we can learn - Trade
Chemical signatures of material used to manufacture ceramics can be traced to a
source. Stylistic adoption from outside a particular area indicates influence as well
What we can learn - Ideology/Religion
Many ceramics are found in burial contexts, and many have scenes relating to mythology or ideology
What we can learn - Social organization
Types of craft production (made by individual or households/ workshops/small or large scale production) can indicate social organization
Ceramic Form - Plate
Height less than 1/5 the diameter
Ceramic Form - Dish
Height between 1/3 and 1/5 the diameter
Ceramic Form - Bowl
Height no more than equal but no less than 1/3 the diameter
Ceramic Form - Vase
Height greater than diameter and no restricted opening
Ceramic Analysis - Classification
The ordering of phenomena into groups on the basis of shared attributes.
Ceramic Form - Jar
Height greater than diameter and restricted opening
Ceramic Analysis - Typology
The systematic organization of artifacts into types on the basis of shared attributes
- Product of the archaeologist or manufacturer?
Most common classification method in ceramic analysis.
Ceramic Analysis - Type-variety analysis
A system of ceramic attributes that produces a classification system based upon formal and stylistic attributes
Ceramic Analysis - Ware analysis
A system of ceramic analysis that produces
a classification based on technological attributes.
- Types are created under a ware using stylistic attributes
- Followed by varieties under a defined type
Ceramic Analysis - Attribute
A minimal characteristic of an artifact such that it cannot be further subdivided; attributes commonly studied include aspects of form, style, decoration, color, manufacturing technology, and raw material.
Ceramic Analysis - Technological Attributes
Attributes consisting of raw material
characteristics including overall shape, the shape of parts, and measurable dimensions – leading to formal typologies.
Ceramic Analysis - Stylistic Attributes
Attributes defined by the surface characteristics of artifacts – color, texture, decoration, and so forth – leading to stylistic typologies.
Ceramic Manufacture - Procurement of Raw Material
Clay is a fine-grained earthy material that develops plasticity when mixed with water, and is used to manufacture ceramics
The ideal qualities of a clay are that it is flexible when wet, yet hard and sturdy after firing
Clay may have been collected from local areas or acquired from long-distances
Ceramic Manufacture - Preparation of Raw Material
LEVIGATING: In order to remove impurities, the clay is mixed with a lot of water, stirred, and left to settle. This process may be repeated several times
KNEADING or WEDGING: This eliminates large clumps of material and makes it more homogeneous
TEMPERING: In order to reduce uneven shrinking and cracking when drying, a temper is added to the clay
Ceramic Manufacture - Forming the Vessel
Hand: A vessel can be simply shaped by hand into the piece one desires to make
Paddle and Anvil: Using a paddle on the outside and anvil on the inside to shape a vessel
Coiling: Creating long thin coils to be placed one upon another
Slab: Creating thick slabs which are shaped together into a vessel
Molding: Pressing the clay onto a form which produces the vessel ( a broken pot or
suspended bag)
Wheel Throwing: This consists of placing the paste onto a rapidly spinning surface.
-The rapid spinning produces evenly shaped vessels with walls of quite uniform thickness.
Ceramic Manufacture - Pre-firing surface treatments
Smoothing and Scraping: To produce an even surface on the still pliable paste using wood, old potsherds, pieces of gourd, knives, and even corn cobs
Paddle and Anvil: The paddle can be wrapped with a number of different materials, giving a specific appearance to the outside of the vessel
Burnishing: When the piece is leather hard, a tool, often a very smooth stone or cloth, is used to smooth and shine the surface
Ceramic Manufacture - Drying
Before a vessel is fired - must be well dried, or excessive steam created by trapped water will cause the vessel to crack or even explode
A potter will often let pottery sit for weeks or months before firing
Temper
The requirements for ceramic manufacture are clay, temper, water and fuel
* Temper is inclusions in the clay. It is added to give the clay strength and workability and to counteract any cracking or shrinkage during firing
* Most common materials used for tempering are crushed shell, crushed rock, crushed pottery (grog), sand, grass, and straw
* Some temper may be aesthetic
* The finer the temper, the stronger the pottery. It usually makes up about 10-50% of the paste (the mixture of clay and temper)
Ceramic Manufacture - Firing
Domestic fires – A ceramic can be placed in a camp fire and rotated around until it is baked
Bonfires – Ceramics are arranged in tiers and fuel is placed on top
Pit fires – A pit is dug, fuel is placed into it, and ceramics are placed on a rack on top. Additional fuel or earth is placed over the vessels to retain the heat from the firing process
Kilns – These specialized structures keep the fuel and the fire separated from the vessels, leading to better control of the firing process
Pre-firing Decoration
There are two types of decoration, PLASTIC decoration, which alters the surface of the clay when wet, and non-plastic or SURFACE decoration, which adds a material such as a paint or glaze to the surface of the vessel
Plastic Decoration
Applique – The addition of three dimensional ornamentation, such as anthropomorphic heads, nodes, or loop handles to the surface of the pot
Impression – Stamping or pressing something onto the surface of a pot.
Incision – Using a sharp object such as a stick to cut a line pattern into the surface of a vessel.
Excision - Cutting out a portion of the surface clay creating a type of bas relief background for a pattern.
Surface Decoration
Slip: A slurry of very thin clay (mixture of clay and water) that is applied over the surface of a ceramic before firing. It often alters the texture and color of the surface of the vessel
Paint: Can be applied to a ceramic object either before or after firing. Natural paints are derived from minerals, plants, and animals
Glaze: A hard, shiny, smooth glassy coating (has a higher silica coating than slip so vitrifies when fired)
Firing - Oxidizing
Result when the fire has sufficient oxygen to burn cleanly and with high heat, resulting in colors such as yellows, reds, and oranges. Complete oxidization produces a uniform color throughout the paste. Incomplete oxidization produces a “sandwich” paste, with light outsides and dark insides.
Firing - Reducing
Result in insufficient oxygen supply to the fuel so that it does not burn cleanly. More soot and carbon from the fuel is added to the ceramic, resulting in colors such as blacks and greys (the temperature was too low or the duration of firing was too short)
Ceramic sherds
Rather than complete vessels, are very common on archeological sites
Rim sherds
Used to estimate the original size of the vessel openings, and what percentage of the rim is remaining
Diagnostic sherds (rim/ base/ handle etc.)
Can inform us about the shape and
decoration of the original vessel
Petrography
Thin sections of ceramics are analyzed using microscopy to identify the mineral and organic components
The identification of these minerals can produce a unique chemical signature which can be traced back to its source of material acquisition and original manufacture
Diagnostic Sherds
Rim Sherd, Base sherd, Handle sherd, foot sherd
Non-diagnostic
Body sherd (usually)
Residue Analysis
Residues scrapped from the inside of vessels can be analyzed to ascertain what types of liquids or foods they initially held, such as brewed chocolate drinks.
Lipids (fats), starches (polymeric carbohydrate) and phytoliths (silica concretions formed in the intercellular regions of many plants) all preserve particularly well.
