Colonial Archaeology: 070 333
Spring 2006 Prof C. Schrire [email protected]
Room 201/202 RAB Phone: 932 9006 Course Outline:
This course will teach the rudiments of identification and analysis of colonial artifacts dating from about 1600-1900 AD. Our teaching collection includes a variety of ceramics, pipes, glass and small finds. The course if taught largely by supervision and not lectures. Students will sort collections, draw objects, measure objects and identify them according to numerous criteria.
Course Requirements:
A prerequisite for this course is 070: 208, Survey of Historical Archaeology, normally taught in the Fall term. Students for whom this requirement was waived are expected to study a suitable textbook on the subject, such as Orser, C. 1995 Historical Archaeology and Deetz, J In small things forgotten.
Students will attend one three hour class, once a week. During this time they will handle material, analyze it, and draw objects. Each student will need a clean writing pad or notebook, a pad of graph paper, pencils, colored pencils, eraser, a ruler, and a divider.
There will be two exams, a midterm and final.
Useful Texts:
1. Noel-Hume, I. 2001. The Artifacts of Colonial America 2. Fournier, Robert. Illustrated Dictionary of Practical Pottery. Paperback, 4th ed. 2000 Radnor Pa. Available at Amazon.com ($31.96) 3. Numerous additional sources will be present at class for used during the practicals.
Colonial Archaeology: 070 330
Significant technical terms: (see Fournier 2000)
Absorption: The taking up of liquid into the pores of a pot. The water absorption of a ceramic is an indicator of its degree of vitrification.
Agate Ware: A pottery body looking like agate stone, and made by layering different colored clays and pressing them together.
Alkaline earths: Oxides of calcium, magnesium, barium and strontium to act as bases (glass modifiers) in glaze function.
Alkaline frits: Alkalis are hard to include in glazes due to their solubility, so they are added as frits.
Antimony: A metallic element (Sb) which added to lead oxide yields a yellow pigment.
Applied decoration: A pellet or emblem of clay pressed onto the pot.
Ash: From trees and plants, and containing metallic oxides and silica taken up from the soil.
Ash glaze: Glaze containing plant ash.
Ball clay: Sedimentary clay, very plastic, that fires to a pale color.
Barium compounds: Alkaline earth, acts as a base in glazes.
Basalt: Volcanic rock used with silica and feldspar in glazes.
Biscuit, bisque: Unglazed ware, usually porous. Refers to the first, (minimum 500-600 C) firing to render clay into ceramic. When red clay is used, the biscuit firing produces terracotta (see also Grog).
Bismuth, oxide: (Bi) Used as a base in glaze to produce mother-of-pearl luster.
Blue pigment, glaze stain: Mostly derived from cobalt.
Blunger: Machine or paddle to mix clay sediments.
Body: Any clay or mix with ceramic materials.
Bone ash: Calcium phosphate, made by burning bone, and principal component in bone china. Can be used as glaze.
Bone china: An English hybrid between soft paste and porcelain. Developed in 18th century and fixed by Spode 1800 to cope with the unplastic nature of English clay that made it difficult to make porcelain. Very translucent and tough.
Borax: used as frit to help lower maturing temperature of glaze.
Boss: Old decorative feature formed by pressing a lump in the clay wall from inside, out.
Brick clay: A variety of clays, mostly red firing and fusible.
Brown pigment: Mostly from iron oxide.
Brushed slip: Slip applied with brush.
Calcine: To disintegrate with heat, used to prepare bone, flint, metal oxides eg manganese, cobalt etc.
Carved mold: Used as a stamp in clay that is pressed into the ceramic.
Cast: Made in a mold; method of molding; molded object.
Casting: A hollow plaster shape is filled with slip. Water is absorbed and a coating of slip is left on the inner surface of the plaster. Slip is repeatedly topped up. When it dries, is shrinks from the plaster mold and can be removed.
Celadon: Solution color range from green to blue gray. Name comes from French classic drama character who wore green clothes. Often found on Chinese stoneware and porcelain.
Ceramic: From G keramos, burned stuff or earthen vessel.
China clay, kaolin: Pure clay. Found in relatively few places, eg China, and Cornwall, UK. Relatively poor plasticity due to large particle size. Used for glazes and to achieve whiteness.
Chromium. Cr. Used in glazes to achieve green.
Clay; Results from decomposition of granite and igneous rocks where alkalis are leached out, and quartz, mica and clay remains. They are grouped according to refractoriness from fireclays (up to 1500C) to red clays (1100C) to marls etc.
Cobalt Co: As an oxide it gives stable blues.
Coiling: Pot making building up coils. Used world wide, and trans- culturally: is used to make very large pots.
Colored glaze: Color added to otherwise clear glaze in form of pigment oxides of various metals, or fritted mixtures of oxides in prepared stains.
Comb decoration: Scoring a pot with a multi-toothed instrument.
Crackle: Intentional crazing of stoneware and porcelain glazes.
Cull: Waster or kiln-spoiled pot.
Decoration: See sgraffito, slip trailing, etc
Deflocculation: Dispersion of particles in a clay slip, usually for casting. Done using electrolyte to alter charges on molecules.
Dish: Shallow container, flat bottomed.
Dolomite: Mineral, double carbonate of calcium and magnesium. Used in stoneware glazes as a flux.
Drying: Accompanied by shrinkage. Pot gets leather hard and changes color.
Earthenware: Pottery with porous body, with or without glaze. Includes majolica, delft, faience, most slipwares, and fine-grained Queensware of Wedgwood. Usually fired at 800 C. Dividing line between these and stonewares is 1200 C.
Earthenware glazes: Called “soft glazes” and must mature below 1150 C. Include lead glazes, tin glazes, lustres, enamels etc.
Enamel: On-glaze pigments with firing range 690-850C. Applied to already fired glazed ware, that was first given a biscuit firing, and then given a last, third firing. Pigments are mixed like oil paints with fat oil of turpentine.
Engobe: American term for slip. Engobes are made up mainly of materials associated with glazes, like feldspars, flint, and fluxes, with very little plastic clay. They are often white or near-white, and serve as base for the coloring oxides.
Faience: Once fired tin-glazed wares from 18th century France. Word comes from town of Faenza where majolicas were made. In Holland, faience denotes vessels with tin-glaze on both surfaces. In USA, it denotes tin- glazed decorated pottery. At Jamestown, it is distinguished by having kiln- marks inside.
Fat oil: Thick residue from turpentine forming after prolonged exposure to air.
Feathering: decoration with trailed lines and dots of slip are drawn out with a feather. It trails the base slip and the trailed line, but should not cut through into underlying clay.
Feldspar: group of minerals decomposed from granite and igneous rocks and allied to clay. Used a flux, in bodies, glazes, and engobes.
Filler: A silica or other agent used in clay body to control shrinkage or alter behavior in kiln.
Firing: heat treatment of ceramic materials. Range from 0 to 1400 C will determine such things as when clay turns to ceramic (600C) or to glass in vitrification (1200 C-1400C).
Flint: Dark gray pebbles found in chalk, used to provide silica in glazes and bodies, and to whiten bodies.
Flocculation: Aggregation or coming together of particles in suspension.
Flux: An oxide or base, that lowers the melting point of an acidic oxide, especially silica. and controls hardness of body and glaze.
Foot ring: Or foot rim: Low pedestal on which the bowl stands. Can be made as the bowl is turned, or made separately and applied later.
Frit: A ground glass or glaze used to ensure uniformity of color.
Fuming: Materials put in kiln to fume and alter the surface appearance of a glaze, eg slat glaze.
Glass: A melt of inorganic materials cooled quickly to prevent crystalisation, and retaining an amorphous structure. Glaze is a special form of glass containing alumina with a comparatively low thermal temperature.
Glaze: A ceramic glaze is a special form of glass with higher alumina content and lower thermal expansion, which increases viscosity and helps it adhere to clay body. All glazes start as mixtures of water, oxides and minerals. The recipes for glazes in the past, were in terms of their mineral contents: today, they can be found in their Seger formula, which discusses glazes in terms of molecular equivalents.
Glaze appearance: Depends on whether successive glazes are applied, thickness which can produce crazing etc.
Glazing: This is a critical part of ceramic production and can be done in many ways: immersion of pot in the glaze; pour glaze over pot; filling; spraying; swirling glaze inside vessel.
Green pigment: Copper oxide or carbonate. Danger in using copper in lead glazes because it releases the lead.
Grog: Ground up fired biscuit or glazed ware incorporated into clay bodies to help when throwing the pot, or to help drying, or increase firing strength.
Handbuilding: Making a pot without a wheel or coils.
Igneous rock: Rock which was once molten and cooled. Slow cooled example is granite, where rocks have recrystalized into mineral, with high silica content vs. basalt, cooled fast with fine crystalline grain and lower silica content.
Impervious: Will not absorb water.
Impressing: Decoration like a stamp or roulette pressed into clay.
Impurities: Anything not in the formula of the clay or glaze.
Iron (Fe): Oxides used in glaze for brown and buff colors.
Kaolin: Chinese Kao (high) Ling (hill) for mountain where it was found. It is synonymous with China clay.
Koalinite: The true clay mineral.
Kiln: A box of refactory bricks into which heat is introduced.
Kiln marks: Scars in the glaze that expose the clay body, showing where spacers were placed between the pots. These are seen sometimes in old bellarmines where they touched against each other in the kiln. They are called Plucked ware.
Lead, oxides, compounds: Pb. A base or flux, and the main one in soft glazes. Does not contain boric oxide. It adapts well to tension (expansion in firing). Very common in early pottery.
Lead glaze: Lead can be used as the only flux in an earthenware glaze. Usually used in once-fired wares. Pigment oxides dissolve easily in lead glazes, eg green from copper, blue from cobalt, purple brown from manganese. Toxicity means it is barred in many places today.
Leather-hard: A stage in drying when the clay is rigid but still damp, and most shrinkage will have already occurred.
Lug: Small handle or pierced handle through which a rope can go for carrying. Lustre: Metallic coating on glaze to produce iridescence.
Majolica: For pottery industry, a majolica glaze is a soft, opaque, colored glaze firing at 980-1080C. For craft potters, majolica denotes painting with metal oxides on a white tin-opacified earthenware glaze. For Dutch, it is a coarse earthenware with white tin glaze on both surfaces. For Jamestown, the kiln-marks are on underside.
It is made like this: The plate is evenly coated with an opaque glaze we call “tin glaze”, being a lead glaze with 10% tin oxide. It is allowed to dry out a bit, and then the design is then painted straight on to the raw glaze, using pigmented oxides. Sometimes a clear glaze is applied over, sometimes not. Great care is taken in loading the kiln so as not to smear the designs.
Manganese: Mn. Oxide used in glaze for a purple-brown color.
Mold: Any former over which clay can be shaped.
Non-vitreous: Pottery body where glass phase has barely begun, eg soft earthenware or porous biscuit. Water absorption is above 10%.
Once-fired pottery: Also called “green glazed pottery” : This bypasses the biscuit stage by glazing the raw clay and firing both together. problems may arise from this due to the different effect of heat on clay and glaze.
Orange-peel glaze: A fine crinkly surface associated with salt glazes that varies in texture according to the grain of the underlying body. Very characteristic on stoneware bottles or bellarmines.
Overglaze: Color applied on top of the glaze. In majolica, colors are applied on raw glaze.
Oxide: A compound of an element with oxygen.
Parts of a pot: Body part terminology used here, ie foot, belly, shoulder, neck. Top edge is the rim.
Paste: Any body mixture.
Permeability: The rate at which a substance, gas or liquid, can pass through another. In pottery, the rate at which water will pass through a ceramic body.
Pigment oxides: various metals whose oxides provide color or opacity to glazes.
Pipeclay: White firing calcareous clay used for tobacco pipes.
Plasticity: The property which permits the shape to be altered by pressure, and yet retain the shape when the pressure is removed.
Plucked ware: See kiln-marks.
Porcelain: kaolin and silica with a little flux, fired to vitrification point at about 1400 C. This is the true or hard paste porcelain.
Porcelain glazes: Very high silica content. Feldspar is the main mineral in most porcelain glaze recipes.
Porosity: Denotes both water absorption and permeability.
Potsherd: A broken bit of pottery.
Pottery: Fired clay objects.
Pyrometric cone: Heat indicator that bed at given temperatures.
Raw clay: Green, unfired clay.
Red clay: Iron bearing secondary clay, including brick clays.
Red color: Uses now selenium and cadmium.
Roulette: A tool, like an engrave wheel or cylinder, to produce a repetitive decoration.
Saggar: Clay box in which pottery is fired to protect from flame and ash.
Salt glaze: Once-fired stoneware is glazed by throwing salt onto hot fuel at 1200C. It decomposes into chlorine gas and sodium, and the sodium reacts with the silica in the clay to form a thin orange peel glaze.
Sgraffito: Decoration where the slip is scratched away to reveal the clay body beneath.
Silica: The principal glass firing oxide found in body and glaze. It can be derived from calcined and ground flints or ground quartz.
Slip: Any clay or body mixed with water to a creamy consistency, and used as a slip, or a decoration as in feathering, sgraffito, trailing etc.
Slip glaze: A slip which will melt to a hard glossy surface at high temperature.
Slip trailer: Bag with small holefrom which the slip can run out to form a pattern.
Slip trailing: See trailing.
Soda: Sodium oxide added to glazes.
Soda glaze: Most glazes have some soda added as a frit.
Soft paste: Experimental glassy bodies produced from 14th -18th century to imitate oriental porcelain. Firing around 1100C. The correct mix was finally reach in 1800 as bone china.
Sponge decoration: Sponged on to the pot to simulate patterns and trees.
Stoneware: High fired (1400 C), impermeable, porosity no more than 5%, low iron content in body.
Temper: Material (straw, broken baked clay, sand, shell) added to clay to improve pot. Common archaeological term.
Terracotta: (Cooked earth). Unglazed red clay, or fired red clay at up to 950C.
Throwing: Hand forming of hollow shapes on a revolving wheel head.
Tin (Sn) oxide: Does not dissolve up to 1200C. Used in soft glazes for majolica painting.
Tin ash: Tin calcined with lead as a glaze.
Tin glaze: Any glaze that owes its opacity to tin.
Tongue test: Test of tongue against body on broken sherd to test porosity.
Trailing: Decorating with slip or glaze extruded through a nozzle or slip trailer.
Transfer: Designs printed on special paper and applied to biscuit or glazed ware. Paper is then peeled away.
Turning: Trimming of pot on a wheel.
Underglaze color: Pigment applied to raw clay or biscuit and covered with a glaze. Oriental ceramics can be sometimes “underglaze blue”
Vitreous: Glassy or containing glass materials.
Waster: A spoiled pot often discarded on the site of the kiln. Very useful to archaeologists as a guide to production sources.
Yellow, glaze, pigment: Sources are antimony, iron, cadmium, etc. Antimonate of lead used on majolicas. Check list for artefact identification
NAME:
Artefact # ---
1. Ware: ∆ Coarse earthenware ∆ Refined earthenware ∆ Stoneware ∆ Porcelain ∆ Other
2. Subclass: ∆ Faience ∆ Majolica ∆ White salt glazed ∆ Creamware
∆ Pearlware ∆ Jackfield ∆ White ware ∆ Oriental
∆ European ∆ Other
3. Fabric: ∆ Color ∆ Permeable ∆ Impermeable Inclusions
4. Kiln marks: ∆ Inside ∆ Outside
5. Sherd type: ∆ Rim ∆ Foot/Base ∆ Body ∆ Neck ∆ Handle
6. Vessel form: ∆ Dish ∆ Bowl ∆ Plate ∆ Cup ∆ Saucer ∆ Pipkin
∆ Jar ∆ Tile ∆ Bottle ∆ Other
7. Diameter:
8. Glaze: ∆ Inside: ∆Outside:
∆ Lead ∆ Tin ∆ Salt ∆ Felspathic
9. Decoration: (slip, design, technique) ∆ Inside ∆ Outside
∆ Hand painted ∆ Slip trailed ∆ Sgraffito ∆ Other
∆ Colors and minerals used:
∆ Sequence:
9. Date:
10. Full Identification ( eg majolica, pearlware; full description) Sketch if needed: Use reverse page if necessary.