The Benefit of Hindsight

Some Tips on Commissioning Paint Analysis

The following is an article based on a paper given at the English Heritage Layers of Understanding conference that took place in London on 28th April 2000.

Introduction

Architectural paint research has progressed enormously in the sixteen years that I have been involved in the field. It is increasingly understood that properly conducted analysis can reveal a great deal of information about a room's decoration, development and use. However, there is still some confusion about how such work should be commissioned and carried out.

The aim of this paper is to provide a number of tips to the potential client in order that he may get the best out of his project.

It should go without saying, that when one employs a paint researcher, it is essential to ensure that he ¹ is capable of carrying out the job. How does he intend to set about it ? What projects has he worked on in the past ? What techniques does he propose to use ?

Scrapes

The first thing to stress is that a paint scraper, or "scrapist" (the word derives from "quack"), will not be able to provide any meaningful information about the sequence of paint layers applied to a surface. Pigment identification, the dating of individual schemes, and the ability to identify (for example) exactly which cornice elements were gilded, and at what stage, are not possible by scraping through layers of paint. ² A white-coated lab technician, on the other hand, may be able to provide an elemental analysis of each of the components within a paint layer, but will not necessarily understand the appearance of a scheme, nor the intention behind its use.

Standards

Until the recent release of English Heritage's Draft Guidelines on architectural paint research, it had been fourteen years since Frank Welsh, the American paint researcher, published his "Call for Standards" in a North American preservation journal.³

In his article, Mr Welsh listed the minimum requirements of a paint analyst as being..."a:

1) Working knowledge and developed skills with stereo and polarised light microscopy and microchemical testing techniques, demonstrated through specific study and experience.

2) Comprehension of architectural building history and technology, demonstrated through specific study and experience.

3) Knowledge of historic architectural-finishes' manufacture and application technology, as demonstrated through study, experience, teaching, lecturing, publishing, etc.

4) True understanding and perception of colour and how pigments and paint colours are affected by ageing [sic].

5) Professional willingness and ability to evaluate findings and/or techniques with others who are qualified in relation to individual project/client requirements."

These criteria have not changed, although they do need re-emphasising.

Experience of Researcher

A good paint researcher will probably have been doing the job for ten years or more; will have made some form of contribution to the field, and have carried out a hundred or so projects. In other words, he will be somebody who knows exactly what he is doing. The client should listen to the researcher, whose aim will be to carry out the job as quickly, accurately and efficiently as possible.

Projects take many forms. If advice is wanted on the way that colour was used in an interior of a particular period, a report should not take too long to prepare. However, if an analysis of the paint is required, it is essential that enough time to complete the work is allowed. Whilst it is possible that an interim report can be issued within a few weeks, a full, illustrated report - possibly amounting to seventy or more pages - will take much longer to produce. The size and complexity of the job will obviously have a direct bearing on this.

Whilst understandable, a client should not try to specify the number and location of samples to be taken. It is possible that repairs have been carried out previously, and sufficient samples need to be taken to avoid such anomalies. It is equally possible that surface detailing, or polychromatic decoration, was employed. It is far quicker for the researcher to take all the samples that are needed at one time, than to make an unnecessary return visit. A sketchy report will seldom justify the effort, and may well raise many unanswered questions.

Unrealistic Expectations

On the matter of return visits, occasionally the researcher will need to go back to the site, in order to take confirmatory samples. Time must be allowed for this eventuality. To be told as I was recently, that a project had to be completed as follows, defies belief:

In this case:

The contract, following the tendering operation, was to be awarded on 4th February. Samples were to be removed by 18th February (some two weeks later), and the report was to be submitted by 3rd March (i.e. within a month). Furthermore, access was limited to six hours on Sundays and Mondays, Wednesdays and Thursdays. Accommodation would be necessary, because of the distance from home, and the Tuesday would be spent inactive as the site was closed. This was not just for one room, but five areas of a building known to contain nineteenth century polychromatic decoration.

As if to emphasise the ignorance of the project managers, the colours identified had to conform to RAL numbers.⁴ Quite what would have happened if each of the colours did not match the 180 or so colours in that range was not explained. This business of specified paint colours will be discussed later.

"Cowboys"

As with any specialised, and little understood, discipline, there is no shortage of cowboys. Certainly, there is every reason for a potential client to be hesitant about accepting the first quote for paint analysis. I was recently asked to look at a building where, before my arrival, the information revealed by a paint scrapist was found to be wanting. When asked to recommend somebody who could take and examine cross sections my client had been told that 600 samples would need to be taken from within the room, and that the bill would be in the region of £30,000. My quote was less than a tenth of that.

Clearly it is important to keep costs down to a minimum, but to try and handicap the analysis by limiting the samples to an unrealistic number is self-defeating, and no researcher worthy of that name will comply with such a request. Analysis is not always the answer, and the expense and the information that can be obtained is neither warranted nor relevant in a number of instances. Provided that the original paint is not removed, no damage should be caused by overpainting, and the earlier layers can be left for another time.

An inexperienced researcher may offer to take a few samples from a large number of rooms with the aim of helping the client form an idea of the general treatment. This can backfire if the client, or as happened to me, an English Heritage inspector, then comes onto the scene and insists on knowing how each moulding and element in twenty three rooms had been treated. Three years later, I was still going backwards and forwards in order to answer increasingly specific questions. In spite of being allowed to put in a slightly larger bill for this extra work, it turned into another pro bono job.

The Brief

The paint researcher will want to have a clear brief... why is the project being carried out, and with what aim in mind ? Just to ask for "paint research" is not enough.

Is the first scheme applied to a surface considered the most important, or perhaps that was just an interim scheme applied before the full carbonation of the lime plaster ?⁵  Perhaps an analysis of the first scheme, with a summary of the later "significant" ones would be more useful ? Schemes that are slightly unusual or noteworthy in some way - perhaps painted imitations of marble or woodgrain - might be included in this. Information on the use of gilding, the presence of expensive pigments, or finishes that one might not expect to find on such a surface might also prove of interest.

Bear in mind that if one wants to know about the decoration applied during the occupancy of a notable individual, a full analysis may be required in order to establish datum points both before and after that period. The positive identification of pigments and components within many of the paint layers will be especially relevant in this sort of situation.

Inevitably, however, if a full-blown analysis is required, it will not be cheap. The report following such work may well go into great detail outlining the components and appearance of each of thirty or so schemes applied to a surface, and may involve the use of some bought-in services such as the use of scanning electron microscopy.

Appropriate Information

Having said that, the mighty weight of detailed scientific analysis is sometimes misused, and the results not altogether relevant. When investigating house paint a thorough understanding of the methods and materials of the early house-painter will often enable a clear interpretation of the paint stratigraphy seen under the microscope. The client should listen to the advice of the researcher on the type of analysis appropriate to answering his brief.

A few years ago I was asked to look at a couple of cross-sections in the laboratories of a major museum. The technicians knew that the paint from a late 18th century room contained lead, phosphorous and possibly carbon, but were unsure what this indicated. They did not know whether it was unusual, nor what sort of colour would have been produced. No one in that laboratory had any background in architectural paint.

A few days later, following a lecture, I was asked what methods I employed for medium analysis. I looked rather blankly at my questioner, and said that beyond identifying whether a scheme was in oil or water, there was seldom a need to go further. It was clear that I had failed to convince him, but whether a house paint was based on raw linseed oil, boiled linseed oil, walnut oil, or poppy oil in most cases is not going to justify the expense required to find out. The context will often supply the answer.⁶  If considered important it is possible for such work to be done.

There are some who, having learnt of the potential of paint analysis, set out to employ it at every opportunity. This is a mistake, and will often lead to frustration and a failure to match expectations.

Exterior railings invariably display a sequence of greys, greens, sometimes red-browns, and latterly black. To be asked as I was, a number of years ago, for a full analysis of the paints applied to a set of railings dating from the 1860s made little sense. As a matter of course, I will usually indicate the presence of any date-relevant pigment, such as titanium dioxide (which tends to appear from the late 1920s onwards), and will certainly record the sequence of colours. However, quite what was achieved by having to report on the constituents of each of the schemes, including the undercoats was lost on me, and, I suspect, the client.

The adoption of the "So What" rule will generally prevent a meaningless paint report. The information given should be presented so as to answer that rule. What do the facts reported on tell us about the building or structure? Do they answer the client's brief ? Is the information completely superfluous ? Above all, the researcher must not lose sight of the fact that his report should be comprehensible, and not full of obscure technical jargon.

I well remember going to look at a small terrace of derelict late-eighteenth century houses that were being renovated as part of a housing project scheme. Having walked around the buildings, I suggested that rather than employing paint analysis, the client should consider painting the buildings in a manner that reflected conventions of that period. However, I was persuaded to take samples from remnants of damaged skirting boards, and from joinery that had been removed, poorly labelled, and put into store. The plaster, too, had been hacked off in several rooms and my report was spectacularly unrevealing. Pretty well each paragraph would have failed the "So What" test.

Skills of the Researcher

I have tried to emphasise the importance of appointing a paint researcher who knows his, or her, job. They will have experience of many aspects of decoration, paint, and colour, and will know how to combine theory with practice and be able to assist with the preparation of the schedule of redecoration. But remember, just because the researcher will have a passing acquaintance with science does not mean that he will not know his Adam from his Yenn, nor his Asprucci from his Botticelli.

As well as understanding modern colour theory, the paint researcher will know of early notions of colour harmony; the effect created by combining various pigments; the colours available and popular in certain periods, and have a sound knowledge of early texts on house painting and decoration. He will also have seen the results of numerous redecoration projects. Furthermore he will be able to advise on the correct type and finish of paint to be used. To suggest that he is, almost by definition, somehow visually inept, and lacking in aesthetic sensibility, is likely to be far off the mark.

There is a common fallacy (and this is unlikely to endear me to the two professions), and that is when it comes to matters of decoration, architects and architectural historians invariably know best. They may well be masters of their chosen fields, but are unlikely to have made a deep study of architectural colour.

Sharing of Information

House curators are often so protective of their charges that they are reluctant to pass on information that might help with the paint research. There is occasionally a tendency to regard the paint researcher as a member of one of the mechanical trades. It is frequently the case that copies of building accounts and other documentary information are not passed on, because it is not considered relevant to the project. Furthermore, the researcher is sometimes regarded as not the sort of person who might understand such documents. Even on one of the largest restoration projects carried out in the last ten years, a lot of persuasion was required before I was allowed sight of the allegedly unimportant family papers.

Do consider that a paint researcher, in many instances, can turn a seemingly bald entry in an account book into a colour; into a medium (i.e. oil or water), and also a finish (i.e. flat or glossy). The colour of the border boards in the Privy Garden, at Hampton Court, for example, was identified by a knowledge of the price of painters' work and materials in the 1700s. Analysis of the paint was not possible as the original border boards had long since perished.

Frequently I have been told that there is no information, and almost as though it were an initiative exercise, have been left to learn of the history of the house from the usual sources. After one particular job, I received a letter from the curator thanking me for "the absolutely brilliant" comments on the paint, but then she went on to castigate me for not having referred to her latest version of the guidebook. Had I been supplied with the newest information on the house, the relevant chapter in my report would have been up to date, and the interpretation of the cross sections made somewhat easier.

The "Doubting Thomas"

Exceptionally, one will come across a curator who refuses to believe what has been found, claiming that it counters accepted historic practice, but citing no evidence. The only occasion where this happened to me concerned a series of dark red-browns being identified on doors and skirting boards of an early 18th century London house. It was suggested by the curator that the sequence of schemes with alternating varnish layers, were perhaps undercoats based on red lead, and not the red and brown oxides that had been identified by analysis, and illustrated by photomicrographs in the report. A careful letter, citing numerous documentary and pictorial examples to support the use of brown on doors and skirtings, was enough to deal with that issue. However, one was left wondering whether that historic house would not have been happier employing an interior designer to devise "tasteful" schemes, if that was what was really wanted.

Health and Safety Issues

There is no doubt that a well-trained paint researcher will have wide-ranging skills, but a fearless, death-defying superman he is not.

Perhaps one of the most frequent problems encountered by the analyst is the failure of the client to provide safe, or even adequate, access. Even I, who used to be a military parachutist in a previous existence, find some of the ladders and scaffolds offered to me scary in the extreme. Indeed, there have been times when I have wondered if I would ever complete the sampling in one piece.

It is unrealistic, indeed, can only lead to heavily-qualified statements in the final report, to expect a whole ceiling to be sampled from an immovable platform. If elaborately decorated it is possible that fifty or more samples will need to be taken. Sometimes too, one is asked to examine a ceiling forty or fifty feet high. It is immensely helpful, and reduces much time-wasting, if one can call on help to move the tower.

A researcher is only human and needs a few basic facilities in order to function efficiently. Sites are often cold, and a wise consultant will have learnt to bring adequate clothing, and a sandwich or two in order to survive the day's sampling. However, the provision of water and sanitation, allows one to concentrate fully on the paint in a room, and prevents unnecessary anxiety, and lengthy interruptions while the local geography is explored.

Light too, comes in handy, if one is to make an effective examination. It really does help if the researcher is warned beforehand to make special arrangements if there is no power on site. However, in such an instance one must not be surprised if the expenses part of the final bill is increased to reflect these arrangements. Is it realistic for a London-based analyst to arrange for scaffolding towers and lighting if the job is in Scotland ? Surely the client, will have far better local knowledge of how to arrange these things.

Colour References

Paint researchers are a hardy lot, and have, and will battle on against most impediments thrown in their way, but there is perhaps one thing that is guaranteed to cause them to question the seriousness of their client's intentions. This concerns a frequent insistence that the nearest British Standard, or RAL, colour reference is quoted for each of the colours encountered during analysis.

This almost amounts to the same as Henry Ford's famous dictum:

The customer can have any colour he wants so long as it's black. ⁷

On many occasions the researcher submits his report, and that is the end of his input. Often, years later, he may revisit the site and see a most hideous misinterpretation, something that could have been avoided by a continued, albeit small scale, involvement with the project.

A paint colour should be indicated in the report by a painted sample, and the relevant colorimetric information ought to be included in order that paint can be reproduced exactly.

Spectrophotometry

Spectrophotometry has consigned paint ranges with only 57 varieties to the scrap heap, and now nearly every colour can be reproduced with a degree of accuracy hitherto unknown.

Not only can a paint be produced that matches that found on a site, but it is possible to ensure that each tin that is applied matches the standard (or target) exactly. Can it make sense, having established a decorative scheme by analysis, to mix the paint in dustbins, and then to find out that not quite enough has been mixed. Does no one ever think about future maintenance implications ? Surely it is better to formulate the colour exactly, so that any quantity can be bought on a future occasion with no delay or unnecessary expense ?

For a happy, successful, result it is essential that the client endeavours to work with the paint researcher and not against him. Use him for everything that he can offer. Often as a result of making the inevitable mistakes in his early years he has a great deal of practical experience to draw on.

Patrick Baty

NOTES

1.The use of the male pronoun is purely a literary device. The author also acknowledges that most paint researchers are female.

2.It should be understood that a "scrape" in this context is the action of scraping away overlying layers of paint in order to see what lies below. An "exposure" or "revelation" is the scraping away of superficial layers, having established the stratigraphy by cross section beforehand. This is done in order to provide further information about the earlier schemes.

The argument against scrapes has been well rehearsed. See the following:

Morgan Phillips and Christopher Whitney, "The Restoration of Original Paints at Otis House," Old Time New England. Boston, Mass.: The Society for the Preservation of New England Antiquities, vol LXII, no 1, (Summer 1971): 25-28.

Morgan Phillips, "Problems in the Restoration and Preservation of Old House Paints," in Preservation and Conservation, Principles and Practices. Washington, D.C.: The Preservation Press, 1972: 273-285.

Ian C. Bristow, "Repainting Eighteenth-Century Interiors," ASCHB Transactions vol vi 1982 (1981): 25-33.

Patrick Baty, "The Role of Paint Analysis in the Historic Interior," The Journal of Architectural Conservation (March 1995): 27-37.

Patrick Baty, "To Scrape or Not," Traditional Paint News vol 1, no 2 (October 1996): 9-15.

No literature outlining their benefits is known, though, incredibly, the practice is still very much alive in many quarters.

3.Association for Preservation Technology Bulletin, vol xviii, no 4 (1986): 4-5.

4.A range of colours standardised by the Reichsausschuss für Lieferbedingungen (RAL) [National Board of Supply Conditions]. This organisation was founded in Berlin, in 1925, to regulate and set the standards for quality in industry.

5.Fresh lime plaster has a high pH, and can adversely affect an oil paint that is applied directly on it. Traditionally a surface was allowed to dry out, and the pH levels to drop, before a scheme in oil paint was put on. A water-based soft distemper, which allowed a certain passage of moisture vapour, was often applied as an interim measure.

6.By context, price and location would often suggest which oil was employed:

a) Interior colours would generally be made up with raw linseed oil;

b) An early exterior paint is likely to have contained boiled linseed oil;

c) Being paler, walnut oil appears to have been widely used to obtain a white on large expanses;

d) Poppy oil seems to have been used infrequently. It was the palest of the vegetable oils, and was rather expensive.

7.The Model T Ford Club, "Great Quotes by and about Henry Ford and the Model T". [http://www.modelt.org/tquotes.html]

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