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THE ROLE OF PAINT ANALYSIS IN THE HISTORIC INTERIOR

This article first appeared in The Journal of Architectural Conservation. March 1995: 27-37.

IntroductionThe assumption made by the visitor to an historic house is that the setting and contents are generally displayed in an objective manner. What is seen is how it would have been. But is this always the case, and just how was the final look decided upon? Usually a great deal of thought will have gone into the presentation, yet all too often, in spite of high standards of research and display, an element of subjectivity will have crept in. Sometimes this may be more by design than accident - indeed, recognizing the near impossibility of being completely objective some administrators pay lip service to authenticity. They attach more importance to the history of their own institutions, regarding them as cultural creations in their own right. The next worrying step is to argue that an earlier attempt at restoration, no matter how flawed, is itself worthy of preservation, and interpretation. The result is stagnation, and the rejection of new research.i

Unless the philosophy behind the presentation of a house is made clear to visitors, they may be excused for being confused, and for questioning the scholarly reconstruction on those few occasions that they actually see it.

Few would agree that historic houses should provide the visitor with little more than entertainment and a safe haven from reality. That is in any case a service already admirably provided by the authors of historical romances and the directors of period costume dramas. Good museums should not act as guardians of our sensibilities, cushioning us from the uncomfortable reality of the past. Fact is just as accessible as fiction, and the custodian should make clear the reasons for the appearance of a house and its contents.

It may seem far fetched to invest the display of historic interiors with such importance, but it is the study of their development that contributes to our understanding of our culture and its influences.

While much research has been carried out on the contents of early interiors, and similar care taken with the recreation of an early picture hang, or table setting, the colour of the walls has rarely been accorded the same degree of serious attention.

There can be little excuse for this, since techniques do exist for the accurate investigation of early painted surfaces. It is the reluctance of some authorities to consider the use of such techniques that perhaps should be questioned.

Paint analysisThere are two principal purposes behind the analysis of the painted surfaces of an historic building. The first and most obvious is to form an idea of how a room might have looked at an earlier stage of its existence. The aim will usually be to identify the colour of a particular scheme, or to see whether it had been given a special treatment such as gilding, graining, or marbling.ii Facts known about the development of paint and pigments will often enable the

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specialist to work out a rough date for individual layers of paint. Until recently, this sort of information has largely been sought only for certain prestigious buildings, and so the examples that are given here fall into this category. However, it may equally be obtained from a broader range of housing, about which less is known, and fewer records were made.

The second reason for analysis might be less concerned with the decoration and more with the archaeology and the dating of a structure. Working alongside architectural researchers preparing a detailed report on a building, the paint analyst can be used to determine when or where changes have been made. The site of doors or windows that have been filled in, for example, can be determined, as can the rough date of a new floor or extension. Ideally, the investigation should only begin after documentary research has been carried out - research which is likely to identify areas that have been altered, or that will lead to questions that can be answered by analysis.

In Colonial Williamsburg, Virginia, a gradual investigation of the painted surfaces in certain of their 18th century exhibition buildings has led to a clearer understanding of how the structures developed. As a result, the architectural research department have been able to form an idea of how the buildings were lived in, how they related to each other, and how their inhabitants prospered.

Paint analysis can also be used to disprove myths. The analysis after the fire at Uppark enabled the National Trust to learn that, far from being an undisturbed time capsule, redecoration had taken place in that house throughout the nineteenth century.

In the Octagon Room, at Raby Castle, near Darlington, one of the initial aims of recent work was to match the colour of the white painted dado and joinery, and then to redecorate. Analysis established, however, that the room had been decorated once only, and that the present scheme survived from the 1840s. All that was required in this instance was a careful wash down and localised touching in of areas of damage. Far better and far less costly to have obtained this information before the intended repaint.

Analysis may also be used to record the earlier schemes before they are destroyed. The surface coatings may need to be removed because of a build-up of layers that obscure detail; because wholesale removal needs to be carried out before major repair work can take place; or because poor preparation has revealed itself. Once the paint has been removed nothing can be learnt of the room's original appearance.

There are others who will use paint analysis as a guide and as a confidence-giver before devising a new decorative scheme. They might take what appeals and discard what they consider the more difficult findings - ignoring, perhaps, the gilding and the oak graining. There can be no argument with this so long as no claims are made as to the authenticity of the new scheme. Sadly, however, the fact that analysis has been carried out is often used as an excuse for the result. The reasons for the decisions are often not made clear, and left for others to make their assumptions.

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The present situationDuring the last fifteen years, the question of paint analysis has cropped up at some stage in many of the larger restoration projects. Indeed, it has been used with great success by Dr Ian Bristow, its leading exponent, at such sites as the Breakfast Room at Pitzhanger Manor, in Ealing,iii and in The Casino at Marino, near Dublin,iv but equally the results have been less well handled.v Until greater awareness is made of the procedures involved in the analysis of earlier decorative schemes, its potential will never be fully realised.

Methods of analysisThe basic techniques of paint analysis have their origins at the beginning of the nineteenth century.vi Technical developments have led to refinements, but essentially the investigation of architectural Paintwork consists of three principal processes:

The first consists of the making of cross sections, which can be examined under a microscope. The second process requires the careful removal of each of the layers to reveal what is shown in cross section. The third process involves the analysis of the constituents of particular layers.

Cross sectionsThe number of samples will depend on the complexity of the room and its known history. A single room may require as many as a hundred samples, each measuring about half an inch, to be taken from suitable representative areas. The location of each sample is recorded and each one is carefully numbered. Being very fragile and brittle, they are then set in a clear polyester resin in order to support them during the next stage of the investigation. The paint chip, held firmly by the resin is sawn in half and rubbed down with a succession of progressively finer wet and dry abrasive papers to ensure a completely smooth surface. The aim will be to present an unscratched and optically clear face to the lens of the microscope.

To be of most use, the samples should be complete, and those taken from wood and plaster should still be attached to a fragment of the substrate. Ironwork is less easy to sample, but mill-scale or shiny metal flakes can often be seen, if the sample has been taken correctly.

An attempt must now be made to work out which was the priming coat, which the undercoats, and, most importantly, which the top, or finish, coats. Sometimes, if the layers are very different in appearance, this is a fairly straightforward matter, however, very often there is doubt about the exact number of decorative schemes involved, especially when there are several schemes of the same colour, one after another. The use of carefully selected stains can help differentiate the layers.

The same process may also be used to gain an idea of the structural integrity of the paint layers. Their likely adherence to the wall and their inter-coat adhesion can be gauged by looking at the composition of each layer. A sign of the times perhaps, but an investigation may well be initiated by an insurance company rather than an architect, and will often stem from accusations of bad workmanship. The sheer passage of time has led to a stage where some of the paint has begun to shell off the walls of buildings of a certain age. The combination of poor preparation, a varied sequence of paint types, and the weight of many overlying coats of

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paint all contribute to such horrors. Unfortunately, it occurs most frequently after repainting, and is usually accelerated by the damp conditions that result from overflows and leaks. To redecorate in such circumstances without identifying the extent of the problem could lead to major paint failure, extensive remedial work and further redecoration.

Layeringvii

Whilst a cross section allows one to see the sequence of paint layers, further tests must be carried out to determine the colour of individual schemes. However, this process can only make sense once a cross section has been made, and, using a drawing or photograph of the stratigraphy as a guide, the individual layers are carefully exposed using a combination of solvents and mechanical abrasion. The aim is to uncover the layers as shown by the cross section, and to expose a small area of each for colour evaluation.

The traditional method of carrying out a "scrape" using a scalpel is a slow and very inaccurate method of exposing the earlier layers. It is often more effective to make a small crater with a knife and then to sand the edges to a gradual slope, the paint layers widening as the surface is rubbed down.viii The finished result will look like a bull's-eye, or target, with the full sequence of coats revealed.

Pigment analysisThe third process adopted by the specialist involves the analysis of the constituents of key layers of paint. The individual pigment particles can be isolated and identified, often providing information on the age, colour, finish and purpose of a particular layer. This will usually be done using the polarising microscope, but occasionally a scanning electron microscope (SEM) can be used to confirm or deny the presence of a particular element. The positive identification of Titanium, for example, will indicate that a paint layer is unlikely to predate the 1920s.

Using one or other of these instruments, what might appear an olive green scheme, as a result of layering, might be shown to contain no more than Prussian blue that has been affected by the alkaline nature of the plaster on which it had been applied.ix

Its criticsThere are some who dismiss paint analysis because the findings conflict with their own long-held views on historic decoration. Their good taste is likely to be affronted by pre-Goethean notions of colour harmony.x It may also be felt that analysis will necessarily lead to the recreation of an earlier scheme, possibly one that is at variance with the tried and tested approach adopted by an institution in the treatment of its properties.

Apart from the very real threat to the arbiters of taste and to many involved on the periphery of historic decoration, paint analysis is not something to be frightened of. It is merely a tool, and one that should enable a more objective approach to be taken in the presentation of historic buildings, and lead to a better understanding of the past.

There is little doubt that because the contents of a room would have changed in the two

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hundred years since it was first decorated, the recreation of an original scheme as a matter of general policy is controversial. The post-fire restoration of what had initially been a bright white in the Saloon at Uppark would be a very difficult setting for those who had become used to its aged and mildly faded contents. To some, however, the mocking up of the room to its pre-fire grubby off-grey with artificial wear and tear may be as disturbing as the brashness of the bright white. At least in this example, the decision was based on the restoration philosophy adopted at the beginning of the project, and was only taken after a very comprehensive investigation of the paint had been carried out. Whether or not Repton's original intention for the room is made clear in the new guide book remains to be seen.

In the majority of cases the scientific examination of the Paintwork in a room is not even considered, erroneously linked as it is with the unsympathetic use of modern materials. Fear is expressed that the contents and faded fabrics of a room will be overwhelmed by an 'unnaturally' fresh wall colour. This worry of a perceived mismatch has been used as an excuse for not even trying to establish what colours were actually used. Instead highly subjective allowances are made for 'discolouration and fading' and 'tasteful' colours introduced.

In fact, cross sections taken from a considerable number of early interiors reveal that rooms were generally repainted at fairly frequent intervals - sufficiently often for the paints to show

i The introduction has drawn heavily from: Chappell, Edward A., Social Responsibility and the American History Museum. Winterthur Portfolio, Vol 24, No 4, Winter 1989. Winterthur Museum and The University of Chicago Press, pp. 247-265.ii Welsh, Frank S., Paint Analysis. Bulletin of the Association for Preservation Technology, Vol xiv, No 4, 1982, pp. 29-30.iii Bristow, Ian C., The Restoration of John Soane's Colour Scheme in the Breakfast Room at Pitzhanger Manor, Ealing. ASCHB Transactions, Vol xi, 1987, pp. 43-48.iv Bristow, Ian C., The Casino, Marino: An Account of the Technical Investigation of the Paintwork and Redecoration of the Interior. ASCHB Transactions, Vol ix, 1985, pp. 40-44.v Hiesinger, Kathryn Bloom, and others. Drawing Room from Lansdowne House. Philadelphia Museum of Art Bulletin, Vol 82 Nos 351-52, Summer 1986. Whilst meticulously researched and examined, a harsh unchanging effect has been created by the use of unsympathetic materials in the redecoration.vi The early identification of pigments is discussed by Stephen Rees-Jones in: Early Experiments in Pigment Analysis. Studies in Conservation, Vol 35, No 2, May 1990, pp. 93-101. One of the earliest accounts of the examination of paint stratigraphy using methods similar to those adopted now was given by A.D. Whitehead in: The Micrography of Paint Films. Journal of the Oil & Colour Chemists' Association, Vol xxii, 1939, pp. 139-148.vii The use of the word "scrape" is best avoided, this is generally used as a pejorative. See Pseudo-analysis.viii Phillips, Morgan W., Weiss, Norman R., Some Notes on Paint Research and Reproduction. Bulletin of the Association for Preservation Technology, Vol vii, No 4, 1975, pp.14-16.ix Recently encountered by the author while investigating the ceiling of a late 17th century garden building in Greenwich, London.x Johann Wolfgang von Goethe (1749-1832). German poet, whose experiments with prisms led him to see Sir Isaac Newton's spectrum in an alternative way. His Zur Farbenlehre (Theory of Colour) of 1810 was to prove very influential in early 19th century England.

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little sign of the deterioration that is occasionally mentioned. The early house-painter knew precisely which pigments reacted adversely together, and which were unstable. Their manuals often contained tables of those that were subject to change by the action of white lead, iron, "sulphuretted hydrogen" or light, for example.xi The house painter who ignored these basic rules would have retained few clients. Undoubtedly there were eighteenth century 'cowboy' decorators, but in normal circumstances the slowly fading contents of a room would have been regularly overpowered by the septennial upheaval. Why then should this suddenly be regarded as a problem?

Perhaps the more important consideration when redecorating is the type of paint used in such sensitive surroundings. Modern paints, in carefully selected colours, may well be the answer for most needs. However, in order to avoid the discomfort still felt by some when confronted with the recreated Adam scheme in the Lansdowne House Drawing Room, use might be made of paints compounded of authentic or near-authentic materials. These will mellow in much the same way as those originally used, continuing the cycle mentioned above.

Pseudo-analysisNeedless to say, as it seems an easy procedure to make a so-called "scrape", there are a number of people practising a form of Pseudo-analysis, merely with the aid of a blunt penknife, and invariably without having taken cross sections. Indeed, one often hears that the decorative scheme in a particular house has been reinstated as a result of the making of "scrapes".

There are several dangers in relying on such primitive "scratch and match" techniques: the first being that it is very difficult to know when one has scraped through one or even two layers if there are a succession of similar coloured schemes. Typically, early layers of stone colour or off-white are confused as undercoats, and if the third or fourth decorative scheme is a bolder colour, it is this that is often mistaken as the first. The penultimate scheme of a deep pink on the walls of the Music Room at Kedleston is perhaps the best known example of this obsolete approach.xii

Needless to say, when this technique is used, the impression given will often be that the research on the paint colour has been as thorough as that on the hanging of the paintings, for example. The result may well be an attractive scheme, but one that has more to do with fiction than fact.

One other problem with relying on "scrapes" is that one sees only what the colour has become, not necessarily what the original colour was. The reason for this is that the oil medium of the early paint yellows when put into darkness by the application of later paints.xiii Few "scrapers" will be aware that the "green" that they are looking at may in fact be a blue distorted by age.

xi Field, George, Rudiments of the Painters' Art or a Grammar of Colouring, John Weale, London (1850). Pearce, Walter J., Painting and Decorating, Chas. Griffin and Co. Ltd., London (1898).xii The room has very recently been repainted in a more appropriate stone colour. See Bristow, Ian C., Repainting Eighteenth-Century Interiors. ASCHB Transactions, Vol vi, 1982, pp.25-33.

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Indeed, none would be able to positively identify the pigments used in a decorative scheme by scraping alone.

When first exposed, it might be thought that the original colours were murky and drab, the sort of colours that until recently would be regarded as suitably subdued to fit in with our preconceptions of the 18th century decorator's palette. However, having exposed the original, scraped, samples to ultra-violet light for a number of hours, in order to get rid of the yellowing nature of the oil medium, one can see the colours as they would originally have appeared. Gone are the putties and drabs, to be replaced by much brighter tints. Imagine how different would be a reconstruction based on such differing colours.

If ever in doubt about the quality of the paint analysis in a building where it is alleged to have been used, a request to see the report will quickly reveal what method has been used. Visible discomfort is often encountered on even the most high profile projects.

It is depressing to see that the techniques for investigating early paint colours have been written about many times in the thirty years since the layman's guide first appeared,xiv and yet it is still regarded as the province of the boffin and the aesthetically maladjusted. How much longer must the visitor to our historic houses rely on the divine good taste of the decorator to inform him, especially when the guide book is unclear or even evasive? Certainly, there is plenty of room for decoration, but the custodians of these buildings should think clearly before allowing themselves to be intimidated, or worse still, selective about their presentation to the public.

Patrick Baty

REFERENCES

xiii Phillips, Morgan W., Discoloration of Old House Paints: Restoration of Paint Colors at the Harrison Gray Otis House, Boston. Bulletin of the Association for Preservation Technology, Vol iii, No 4, 1971, pp. 40-47.xiv Batcheler, Penelope Hartshorne, Paint Color Research and Restoration. Technical Leaflet 15. History News, December 1963.