Orton C., Tyers P., Vince A. Pottery in archaeology
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Minimum standards of publication
107
approach, is to publish both a type-series and assemblages. Variations on this
approach consist of publishing the type-series as smaller scale profiles or
alternatively showing assemblages in the form of three-dimensional recon-
structions or in diagrammatic form.
Indexing and correlation
Whichever means of presentation suits the needs of your report best, the
alternative needs of your readers will have to be catered for in some way. For
example, if pottery is published by archaeological assemblages then a cross-
index by fabric and form would be useful, whereas if it is published by
type-series a list or appendix by context is required. The more variables one
has, the more possibilities for permutations in cross-indices exist. As a rule of
thumb, the longer the report and the more complex the data the more
different means of exploring it should be provided.
Minimum standards of publication
In the 1980s in Britain there was a move away from the presentation of actual
data within archaeological reports. The logic behind this development was
that the actual data would only be of use to a handful of other specialists and
that therefore it was more economical for these specialists to use the archive
itself and for publications to be a synthesis of specialist work. The immediate
results of this development were felt by specialists themselves. If one is not
going to publish the results of a study, only summarise them, then it makes
sense, if costs must be cut, to cut or pare down the costs of the study itself.
The knock-on effect of this was to reduce the number of pottery specialists in
work whilst the ultimate effect would be to stultify the whole discipline. It
therefore seems sensible to lay down minimum requirements for the publi-
cation of pottery from archaeological fieldwork.
Amongst the data which should be published as a matter of course are the
approximate size of the total collection, the means of retrieval and the present
condition and location of the collection. Armed with this information one
could form a judgement about whether it was worthwhile making the
effort
of
examining the archive. There are probably very few instances where these
data alone would be considered sufficient. An example might be where
inconclusive excavations took place which might be intelligible if further
work took place, at which time the pottery might repay analysis.
The next level of detail concerns the date-range, the forms and fabrics
represented and a measure of their
frequency.
Unlike the previous data, such
information should only be provided by a specialist, otherwise it is impossible
to trust the results. There are many occasions when this is probably the only
significant information that need be published about a collection. It assumes
that there is no internal structure to the collection. Either it is unstratified and
randomly distributed across the site or, though stratified, no significant
108 Publication
patterning can be found within it. The final level would be a full report, as
described above. This should be the aim for any site where sizable stratified
assemblages are present, since there is almost certain to be patterning within
such collections. Any cataloguing and quantification systems employed
should be routinely described.
Microfiche and microtype, computer media
In an effort to bridge the gulf between synthetic publication and the archaeo-
logical archive, two novel means of dissemination have come into use. The
first is microfiche and the second microtype. Microfiche are rectangular stiff
plastic cards on which A4 pages of text and illustrations are reproduced
photographically at a very small scale. Using a microfiche reader it is possible
to scan the whole fiche, 96 images, quickly. They can also be read using a
binocular microscope (luckily for pottery specialists). Microfiche are
extremely inconvenient to use. They tend to fall out of the pockets provided
for them in the back of a report and after only a few months begin to show
signs of wear, especially if used in a dusty environment, such as that in which
pottery is typically studied. It is not possible to flip back and forth between
images as one can with a book nor can one hold a potsherd up against a
microfiche image for comparison. They are impossible to use on public trans-
port or in bed, the only places where archaeologists can find the time to read.
Microtype is produced as normal printed pages but the point size used is
such that it can barely be read with the naked eye but can be read using a
magnifying glass. It has been used with success to reduce multi-volume
dictionaries to a manageable (though hardly portable) size and would suit the
publication of data which could be hierarchically organised, as in a diction-
ary, and where one would only need to look at a small amount of print at a
time.
A very recent development is the inclusion of computer floppy disks in
archaeological reports. These could be used in the dissemination of pottery
reports by making the actual archive data accessible. They depend on com-
patibility of operating system and the data should be in a portable format,
such as ASCII. Neither of these is as difficult as it was in the 1980s although
computer technology has still not reached the point where one could rely on
being able to use the medium for more than a few years, if that.
Pottery specialists do it on their own
Another trend in British pottery studies has been the estrangement of pottery
reports, and other specialist studies, from 'mainstream' archaeology. This is
partly a result of the phase in which pottery specialists found themselves in
the 1970s and 1980s. There was an explosion of archaeological excavation
and fieldwork following the growth of rescue archaeology resulting in the
need to publish lengthy reports dominated by the presentation of classift-
Summary 109
cations. As these become established it will be possible for pottery reports to
become smaller and therefore more easy to integrate into the format of an
excavation report. Pottery specialists have, however, found the need to
communicate within their disciplines and journals, such as
Medieval Ceramics
and the Journal of Roman Pottery Studies, are now well-established.
Summary
This overview of trends and principles of publication shows that there is no
one right way of publishing pottery from archaeological fieldwork, although
there are several ways which are wrong. It also demonstrates that there is as
yet no substitute for the printed page as a means of dissemination of data and
ideas.
PART III
THEMES IN CERAMIC STUDIES
10
MAKING POTTERY
Understanding the process whereby the raw materials of ceramics are trans-
formed
into finished ceramic products is a necessary precursor to the examin-
ation of both the products themselves and the remains of the manufacturing
sites.
To set up any system of ceramic classification requires a knowledge of the
underlying physical characteristics of the raw materials, an understanding of
how they are affected by all stages of the manufacturing process and the
ability to recognise and correctly identify the traces of these actions.
Our knowledge of the pottery manufacturing process comes from a variety
of sources. Materials science provides detailed information on the behaviour
of
clay
and other materials under a wide range of conditions, in particular
when mixed with water or heated to a high temperature. Basic textbooks on
ceramic materials (e.g. Worrall 1975; Kingery, Bowen and Uhlmann 1976;
Grimshaw 1980) or briefer descriptions written from an archaeological stand-
point (Shepard 1956, 6-48; Rice 1987, 31-110) may be consulted to provide
the
physical and chemical background to the pottery manufacturing process.
The investigative techniques of materials science have been applied to par-
ticular aspects of pre-industrial pottery (Bronitsky 1986).
Descriptions of traditional pottery manufacturing by ethnographers are a
rich source of information on all aspects of the production system. Earlier
work of this type tended to be largely descriptive, but often overlooked or
failed to record adequately aspects of the materials or process which would
be of value to archaeologists considering material recovered from exca-
vations. There are now increasing numbers of studies of traditional pottery
production by archaeological ceramicists who realise the importance of
recording as much as possible of a fast-disappearing craft in most (if not all)
parts of the world - as much for its own sake as an aid to the interpretation
of archaeological material (Arnold 1978; Nicholson and Patterson 1985;
Vossen 1988; Desbat 1989; review of'ceramic ethnoarchaeology' in Kramer
1985).
The experimental duplication of the styles and techniques of ancient
pottery can also contribute to our understanding of the material from
archaeological contexts. The majority of the interest in this field has been in
experimental kiln-firings (Bryant 1978-9; Lucke 1988), collecting data on
topics such as firing times, fuel usage and waster rates. It is not always clear,
113
114 Making pottery
Table 10.1. Principal stages in pottery manufacture
1 Procurement of raw materials
2 Preparation of raw materials
3 Forming the vessel
4 Pre-firing treatments
5 Drying
6 Firing
7 Post-firing treatments
however, what advantages this type of experimental work has over the
observation of traditional pottery production systems.
A further source of valuable information on pottery manufacturing tech-
niques, particularly forming and firing, are those texts written for modern
craft potters, of which A potter's book by Bernard Leach (1940) has been
perhaps the most influential.
The principal steps in pottery manufacturing described below are summa-
rised in table 10.1. There are many complex interrelationships between the
different steps - due, on the one hand to the character of the raw materials
and tools, the skills of the potter and the pot-making environment, and on the
other, the character of the desired product.
Raw materials for pottery manufacture
The essential raw materials of a ceramic product are clay and water. Non-
plastics (also known as 'tempers' or 'openers') can be added to the clay mix
and slips, paints or glazes may be required to finish the pots. Fuel is needed to
fire the vessel.
Clay
Clays are complex materials but the two principal features are the very small
particle size (less than 0.002mm in diameter) and the high proportion of 'clay
minerals' in the mixture. The clay mineral component is ultimately derived
from the weathering of rocks, and in particular igneous rocks. The small
particle size and the plate-like characteristics of these clay minerals give clays
the physical and chemical properties which allow them to be worked into
shape and fired, creating ceramic.
Naturally occurring clays may be divided into two broad groups: there are
those clays that derive directly from an underlying bed-rock by in situ
decomposition, and there are those that are carried to their resting place by
rivers, glaciers, wind or the sea. These are usually referred to as primary and
secondary (or sedimentary) respectively. Most clays used for potting fall into
the latter category.
Raw materials for pottery manufacture
115
Non-plastic inclusions
The great majority of natural clays include materials in addition to the clay
mineral component. These non-plastic inclusions may, in the case of primary
clays, include unweathered or partially decomposed fragments of the under-
lying source bed-rock. In the case of sedimentary clays a wider range of
materials may become incorporated into the clay during the process of
transportation, each of which has been through a different erosion cycle. As
one of the most durable of the commonly occurring minerals, rounded
quartz grains (the 'sand' of common parlance) are particularly common.
Fragments of shell are also widespread in estuarine or marine clays.
The second source of non-plastics in ceramics are those that are added by
the potter, usually deliberately, but also incorporated with the water or
picked up from tools or working surfaces. In some cases these added
non-plastics are simply more of those Which occur naturally in the clay - a
primary clay with fragments of the source rock may be supplemented by
more of the original crushed rock. More commonly, the added materials are
different to the non-plastics in the raw clay, and, as such, it may be possible
to distinguish between them. A crushed rock which has been added to a
sedimentary clay containing rounded quartz should be distinguishable.
The effects of these fillers on the behaviour of the clay mix are complex
and choosing or creating the right combination of clay and filler is a matter
of getting the balance right for the task in hand. As, unlike the clay, fillers do
not hold water they reduce the proportion of water that can be held in the
clay mix and hence the shrinkage of the clay and the drying time. The more
filler is added the more the shrinkage is reduced (Jacobs 1983). Clays with a
higher proportion of filler tend to have a higher 'wet strength' - they can
support themselves better during the drying process. However the more
non-plastics there are in the clay the more the plasticity is reduced and the
more difficult it is to work. Clays with a very high proportion of filler may
not be suitable for the manufacture of very thin delicate vessels or the use of
a fast wheel.
Tempers other than those of geological origin are well known in both the
archaeological and ethnographical record: crushed and burnt bone and shell
(Steponiatis 1983, 20-43), dung (London 1981) and agricultural by-products
such as straw or rice-husks have been recorded. The effects of organic
materials on the behaviour of clays during forming and firing have been
investigated in some detail (Crusoe 1971; Schiffer and Skibo 1989,603-8). In
particular excessively wet or plastic clays may be turned into workable pastes
by the addition of dry organic material.
Water
The mixture of clay and water results in a plastic workable medium suitable
for forming and firing. Soluble salts dissolved in the water may become
116 Making pottery
incorporated in the clay. Common salt (NaCl) may be added with sea-water,
either mixed with the clay before forming or by dipping the completed vessels
in sea-water before firing (Rye 1976, 121-2). The combination of sea-water
and a lime-rich clay may result in a white surface layer on the vessel (Peacock
1984) which has sometimes been confused with a slip.
Fuel
Fuel is required for the firing process, and perhaps also to facilitate drying
and 'water-smoking', which drives off the excess moisture in the fabric. Fuels
vary in both the quantity and quality (for example evenness) of the heat they
provide and the amount of smoke they produce: these factors affect the
suitability or otherwise of the fuel for a particular function. Modern potters
recognise that fuels produce heat of a different character and may be more
suitable for some part of the firing procedure than another, or may affect the
product in other ways (Rye 1981, 104). Brears (1989, 7) relates a description
of the changes in glaze colour caused by seasonal variation in the fuel, given
by a potter from Truro in Cornwall. In spring the damp fuels produced an
olive-green glaze, which changed with the passing of summer and autumn
through khaki and buff, resulting in a bright orange-red glaze at the end of
the season. Variations such as this must be considered when developing
classification systems for archaeological ceramics.
In the archaeological record very few analyses have been made of the ash
deposits from pottery firings to identify the type of fuel employed although,
in principle at least, plant ash should show a wide range of variation and
should be identifiable using advanced analytical techniques (Middleton
1984-5).
In the ethnographic record, wood is in widespread use as a fuel in tradi-
tional potting, but is often not of the highest quality. Rather, by-products of
agricultural procedures such as prunings from fruit or olive trees, coconut
husks, waste fibres or trimmings from timber shaping are commonly
employed. Animal dung, usually in the form of dried dung 'cakes', is another
common
fuel.
Modern pottery kilns consume oil or gas. Whatever the precise
source of fuel, the quantities consumed by some of the largest pottery
industries of the classical or medieval world must have been prodigious,
comparable, in volume at least, with the supply of clay or the distribution of
the finished products.
Pressure on fuel resources for cooking and heating in many modern potting
communities is intense. Faced with the depletion of their traditional sources
some potters turn to the wastes of industrial society, such as car tyres, while
others turn their hand to activities other than potting (Arnold 1985, 54). The
continuing depletion of fuel resources can only hasten the demise of an
already declining craft.
Forming
117
Clay preparation
Almost all clay requires some form of preparation before it can be used for
forming pottery, even if it is only a little light kneading. Clay preparation falls
into two broad categories. Firstly there is purifying - the removal of extra-
neous unwanted materials such as roots and other organic matter, or large
pebbles. Secondly, it may be necessary to alter the properties of the material.
The aim is to produce a regular, uniform product
from
variable raw materials
- a material whose properties are predictable and controllable, and suitable
for the forming and firing procedures employed. A prepared clay mix suitable
for hand-forming may not be suitable for wheel-throwing or moulding. The
properties desired for the final fired product, such as its thermal character-
istics, mechanical strength or porosity may also necessitate a range of prepar-
ations, and different clay mixes may be used for the production of
different
vessels according to their function.
In addition to simple mechanical sorting, more sophisticated preparation
procedures may be employed. The clay may be mixed with water in large
settling tanks (Peacock 1982, 54). The process of levigation allows the coarser
fraction to settle out. Two or more types of clay may be mixed, perhaps with
the addition of non-plastic tempers.
Forming
A very wide range of techniques are available to potters to form their wares.
Many vessels are formed in several stages by a combination of methods which
may be visible on different parts of the vessel (or, in an archaeological
context, different sherds). The complete story of the formation procedure
employed for a particular vessel is usually only recoverable from the con-
sideration of all its parts.
Descriptions of the principal forming techniques are to be found in a
number of publications - those by Rye (1981) and Rice (1987, 124-44) are
particularly valuable. A broad distinction may be made between primary
forming methods, which produce the basic form of the vessel, and secondary
methods, which further define the details of the shape, even though in many
cases the complex actions of the potter will somewhat blur the boundaries
between these. The primary forming methods employed may be considered in
two groups (Edwards and Jacobs 1986):
Hand-forming - the building or forming of a pot by any means
without the use of
centrifugal
force.
Throwing - forming a vessel on a wheel which is rotated at a speed
sufficient to allow the potter to use centrifugal force as an active
agent in the forming and shaping of the vessel.
The forming techniques employed can be identified by a variety of
methods. The surface and core of the vessel wall often retain traces (Rye
118 Making pottery
1981, 67-95 and Balfet et al. 1989, 52-63 provide useful sets of photographs
and keys to identification), but for cases where these are unclear, or perhaps
where several techniques overlap, resort to more sophisticated procedures
such as radiography (Rye 1977; Glanzman 1983; Carr 1990) or tangential
thin-sections (Woods 1984-5) is possible.
Hand-forming and building techniques
The simplest pots are made by pinching a hollow in the centre of a lump of
clay and forming the shape of the vessel between the thumb and fingers. This
technique is generally used only for the production of the simplest of small
round-bodied vessels, or as a secondary technique to form additional pieces
to be added to a vessel formed using another primary technique.
In slab-building, flat sheets of clay are joined together by squeezing or
pinching them together at the edges. Although particularly suited for the
construction of rectangular vessels, circular pots can also be made using this
technique. Pots can also be formed by joining together a series of coils, either
as rings or as a continuous spiral. Adjacent rings are invariably smoothed
together but may show themselves as a series of corrugations, or even as weak
lines where the vessel breaks or cracks.
Once a vessel being formed exceeds a certain size, it is invariably necessary
to move the vessel around so that the face being worked on is nearest the
potter. The pot may be placed on a simple mobile support such as a mat, a
specially made pot support known as a batt (or bat) or even a large sherd
from a broken pot. Bats are usually circular and made from wood or stone, or
may themselves be made of a coarse ceramic (fig. 10.1).
One step up from such pot supports is the use of a simple turntable - a
platform supported on a central spindle and capable of rotary motion. Such
devices have been widely used in traditional potting and although they may
be rotated, even continuously with the help of an assistant, they are not
suitable for 'throwing' a vessel, as a true wheel would be (Edwards and
Jacobs 1986, 50-3).
The use of moulds (or molds) to form pottery is widespread at many
periods, but within this broad category a variety of techniques are available.
In the simplest case a hollow object, such as a basket, the base of another pot
or even a simple leather mould (Franken and Kalsbeek 1984) may be used to
hold and shape the clay during hand-forming: this is closely related to the use
of a flat pot support.
More sophisticated moulds are also used to form either entire vessels or
particular parts of vessels. Of particular value are those with incised or
impressed decoration on their inner face. Any vessels made in them will then
have relief decoration on the surface. Simple basket moulds may leave traces
on the vessel surface, but the classic example of the use of moulds is the early
Roman arretine and samian industry. The study of samian moulded wares,