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Problems and Ethics of the Restoration of Pottery

Studies in Conservation
ISSN: 0039-3630 (Print) 2047-0584 (Online) Journal homepage: http://www.tandfonline.com/loi/ysic20
H. W. M. Hodges
To cite this article: H. W. M. Hodges (1975) PROBLEMS AND ETHICS OF THE RESTORATION OF
POTTERY, Studies in Conservation, 20:sup1, 37-38, DOI: 10.1179/sic.1975.s1.007
To link to this article: http://dx.doi.org/10.1179/sic.1975.s1.007
Published online: 04 Jul 2014.
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H. W. M. Hodges, Queen's University, Kingston, Ontario, Canada
The conservation and restoration of ceramics are not subjects that have figured prominently in the pages of
'Studies in Conservation' over the past years, while H. J. Plenderleith devoted only seven pages of text to the
entire subject in the first edition of 'The Conservation of Antiquities and Works of Art' [1] ..One could thus be
forgiven for supposing that there exist few real problems in this field, an attitude which gains considerable
support from two widely held and popular beliefs.' The first of these is that pottery 'has the essential quality of
lastingness: any properly fired ware is indestructible in ordinary conditions' [2]; while the second is that
'building up a pot from broken sherds needs patience and dexterity rather than any special knowledge' [3]. These
attitudes, here voiced by archaeologists, seem to be equally subscribed to by many conservators. The fact that
ceramics do survive under the majority· of natural environments, and continue to survive without undue obvious
damage under many laboratory treatments, has encouraged the use of processes that in the case of any other
material would be considered totally inadmissable. Thus one is enjoined thoroughly to dry out pottery before
washing it; to impregnate it with a consolidant before removing superficial dirt, and to dry it in an oven at a
temperature which is not specified. Harder pottery may be scrubbed with a nail-brush to remove dirt, while
incrustations of .lime are to be removed by soaking it in dilute citric acid, followed by several rinsings in clean
water [4]. As to restoring pottery, advice may come in the form of entire volumes [5] or as sections of
handbooks (6]. In either case what is largely discussed is technique, and too often the ethics of restoration are
relegated to a single passage which may be paraphrased as a choice between making the restored parts discernable
or not, as the case may be.
Two decades ago, when most of the works just referred to were first written, far less was being asked of
ceramics than is the case today. At that time, the shape and style of pottery, its techniques of production and
decoration were essentially the only features considered either by archaeologists or art historians, and provided
that the visible material evidence was left intact, what was done byway of conservation or restoration mattered
little. The ever increasing use of chemical and physical methods for examining bodies and glazes, and the
introduction of methods of dating by thermoluminescence (TL) have imposed a new set of criteria upon the
conservator who must ask himself what is the precise effect of any treatment he may devise upon the ceramics he
is supposedly conserving. Thus even the most time-honoured and bland of processes, the removal of highly
soluble salts by prolonged soaking in changes of water, is not beyond criticism if conducted with excessive zeal.
Certainly the soluble salts will be removed, and so to an extent will other less soluble materials that may well be a
part of the original composition of the body, as for example calcium carbonate [7]. The removal of surface
incrustations with dilute acids can be even more damaging. Since these deposits were normally laid down from
solutions, and since the pottery may well be porous, the probability is that the incrustations lie not only on the
surface but also in the interstices. An acid treatment aimed at cleaning the surface may achieve only that end,
leaving a mass of extraneous material in the pores to confuse subsequent analysis. Equally, the acid may remove
not only the incrustation on the surface and in the interstices, but also acid-soluble components of the body,
again confusing any analytical results. To complain that the analyst should not be examining ceramics that have
been so treated (as indeed he should not) ignores the fact that he may be unaware that it has been carried out,
especially where laboratory records and object have become separated. The same objections 'can be raised to the
more violent forms of cosmetic treatment such as the removal of layers of decayed glaze with hydrofluoric acid
[8]. Briefly, the analyst is entitled to know whether what he is looking at is original or whether it has been
'improved' by the removal of some unspecified part of it. The remedy lies ina more careful scrutiny of pottery
before it is given any treatment whatever, and perhaps a less extensive use' of cosmetic treatments, even at the risk
of leaving at least some of the pottery in a less-than-perfect state.
. Most conservators are aware that the phenomena on which TL dating methods are based are destroyed by
excessive heating. The matter need not be laboured here save to point out that enthusiastic drying, especially with
hot air blowers where very high •local temperatures may result, and· the· use of heat. to solidify thermo-setting
resins, can quite accidentally achieve the same damage as deliberate heating. As things stand, those involved with
TL dating.techniques are rightly suspicious of ceramics·thathave been through· a conservator's hands: ideally they
should not have to be.
When it comes to consolidating and mending broken pottery most conservators subscribe, in theory, to the
principle of reversibility, supposing that if an adhesive has a known solvent it can,if need be, at some later date
be removed. In practice such a removal is very difficult to achieve, but this in itself does not justify the use of
resins that\ are known to become insoluble in· time. Those who are concerned with the restoration of
archaeological ceramics are perhaps more conscious of this problem than others, and it is sometimes argued that
in the case of historically well-dated ceramic objects the removal of repair materials will not arise. The same view
could have been argued by archaeological conservators about all their processes a quarter of a century ago.
However enticing some of the newly developed resins may seem, one wonders whether their wide-scale
application today will appear quite so justifiable when lIe celebrates its fiftieth anniversary. Indeed, today the
conservator and the manufacturer of adhesives seem to be in direct conflict. Unlike dUl'flbility and the ability to
resist detergents, reversibility is not a strong selling feature for an adhesive. With an ever increasing range of
polyester and epoxide resins from which to choose, so does the temptation to use them become stronger. One can
only hope that they lack the stability claimed for them by their manufacturers.
The development in recent years of historical archaeology, by which is meant the excavation of historically
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recent sites, has had the result that one is now faced with the remains of vessels, better examples of which already
grace our museum shelves. In many cases such pottery 'will be in a deplorable condition from the point of view of
both physical damage and chemical change. Lead-glazed vessels, especially those originally coated with raw glazes,
tend to suffer greatly if buried under anaerobic conditions where sulphur-using bacteria thrive. In extreme cases
the whole surface may become totally blackened due to the formation of lead sulphide. By cautious refiring and
the addition, if need be, of further small quantities of raw glaze materials, such wares can be brought back to
something approaching their original condition. The results can be most dramatic, but one needs to ask whether
this kind of exercise is one in which conservators should indulge. The question must be put because it is
technically possible to restore nearly all the ceramics from historical sites to a condition close to that of the
pottery in fine art collections, although it would be a very time-consuming and expensive process.
The standard of restoration adopted or, if one prefers, the degree of deception practiced by restorers, as
already noted, is a subject that receives scant attention, despite the fact that it is fundamental to the whole
process of restoring pottery. It would, in fact, appear that there exist only two valid reasons for restoring pottery,
and those reasons need to be considered if good restorations are to result. First, there are many occasions when it
becomes necessary to display a number of sherds in a more intelligible form. If the fragments are to make any
impact on the viewer some kind of reconstruction is essential, despite the fact that the sherds may represent only
a small part of the entire vessel. Such restorations are no more than a technique for displaying otherwise
meaningless fragments, and their intention is only to allow the viewer to relate the sherds to the type of vessel
from which they came, no attempt being made closely to simulate the original vessel in the reconstructed parts.
This class of restoration has to be carried out more commonly by restorers of archaeological ceramics, for obvious
reasons, than by others, and has a very close parallel in the style of restoration often forced upon those dealing
with severely damaged mural paintings.
The second reason for restoring ceramics needs very precise statement. It is to present the original craftsman's
work in a form in which it will communicate to the viewer, as nearly as possible, what that craftsman intended to
communicate in the first place. This does not say, and does not imply, the restoration of ceramics in appearance
and form to their first perfection, let alone does it aim at repairs that are unidentifiable [9] . It means, rather, the
rigid application of the code of ethics drawn up in the Murray Pease Report [10] . It further demands that missing
pieces should be restored in such a way that they neither distract nor give the immediate impression of being
restorations. Again for obvious reasons this style of restoration is most commonly practised by conservators
dealing with fine art collections, and has a close parallel in the kind of work done by restorers of oil paintings .
. Unfortunately the custodians of collections seldom appear to recognize that both types of restoration are
perfectly valid, and that they could, and should, co-exist in any museum. Instead one sees the application of
blanket regulations enforcing one or the other style, regardless of specific cases, throughout an entire collection.
Hence, in a museum in which the custodian is an archaeologist, one may see superb pieces of pottery made
hideous because .a few missing sherds have been left in glaring contrast. Equally, one sees in some fine art
collections carefully disguised restorations that transcend all rational and ethical limits. In short, the decision as
to which type of restoration should be adopted should not depend upon whether a vessel is old or recent, has
been buried or not, is in a predominantly archaeological or fine art museum, nor yet upon the whims of a
custodian, but upon its own merits. Such decisions demand more of conservators than mere patience. and
Plenderleith, H. J., 'The Conservation of Antiquities and Works of Art', Oxford, 1956.
Hawkes, J. and Hawkes, C., 'Prehistoric Britain', London, 1949, p. 162.
Atkinson, R. J. C., 'Field Archaeology', London, 1946, p. 214.
Atkinson, R. J. C., 'Field Archaeology', London, 1946, pp. 214-5.
Plenderleith, H. J., 'The Conservation of Antiquities and Works of Art', London, 1956, pp. 326-7.
Wheeler, Sir M., 'Archaeology from the Earth', Lond9n, 1956, pp. 185-7.
Parsons, C. S. M. and Curl, F. H., 'China Mending and Restoration" London, 1963.
Pond, T., 'Repairing and Restoring China', Toronto, 1974.
Gedye, i., Pottery and glass, in 'The Conservation of Cultural Property', UNESCO, Paris, 1968, pp. 109-114.
Guldbeck, P. E., 'The Care of Historical Collections', Nashville, 1972, pp. 126-130.
Freeth, S. J., A chemical study of some bronze age sherds, 'Archaeometry' 10 (1967), 110-11l.
Plenderleith, H. J., 'The Conservation of Antiquities and Works of Art', Oxford, 1956, p. 329.
Parsons, C. S. M. and Curl, F. H., 'China Mending and Restoration', London, 1963, p.20.
Pease, M., 'The Murray Pease Report', New York, 1968, p. 56.