Paint on Historic Metal Work

Historic metalwork poses many difficult issues for conservation professionals. The treatment required for the long term preservation of the substrate often appears at odds with the preservation of the paint archaeology. In addition, the choice of materials to protect and decorate historic metalwork, whether it retains earlier coatings or not, is difficult and fraught with the risk of failure and further deterioration of the metal substrate.

This complex and difficult subject will be the focus of this year’s Traditional Paint Forum conference. Using the prism of transport and industrial heritage, a range of specialist will consider the analysis, use of colour, ethics and choice of materials and techniques.

You can find out more about the conference on the TPF website traditionalpaintforum.org.uk or on the eventbrite booking page 

What is Historic Paint Research?

Detailed assessment and recording of accumulated layers of paint allows us to interpret changing use of colour and materials, enhancing our understanding of how our architectural heritage looked, how it was used and how shifting fashions, ownership and financial means contributed to the narrative of a site. Our choice in decoration, like those of our ancestors, tells a great deal about function, taste, personality, fashion, social standing and wealth.

Architectural paint research involves meticulous analysis of archival documentation, building pathology and paint archaeology to create a detailed history of more than just colour.

The scope of a research project is dictated by the project requirements, but generally includes:

Archive research

Archive information can provide significant insight to the paint researcher and should not be overlooked; understanding the development of the site can reduce the time required in understanding the paint archaeology, and allows a more thorough and detailed interpretation of the decorative history.

Identification of sample sites

Samples are generally taken from each profile element of the architecture. The reason for this is to establish the presence of any picking out to various elements. If the schemes are to be accurately investigated, understood, recorded and recreated then this is essential.

Collection of samples

It requires experience and skill to identify the best locations for samples. The samples are collected and recorded.

Cross section analysis

Samples are embedded in clear casting resin and polished to provide a cross-section through the  paint strata. The samples are assessed under visible-range and UV light illumination.

Stratigraphic sequencing

The paint archaeology is plotted in a matrix to illustrate the chronology of decoration. The resulting table provides an easily accessible reference and is a useful project tool.

Pigment and binder analysis

Knowledge of pigment types can play an important role in dating paint schemes. For example, the presence of white pigments lead carbonate, zinc oxide and titanium dioxide allow paint films to be considered within certain periods of time.

Understanding the type of paint binder is also important, especially where failure or incompatibility issues may arise.

In-situ investigation and recording of paint archaeology

In situ recording and investigation, referred to as uncovering or layering tests, will involve the photographic recording of extant finishes, as well as careful removal of overpaint, scheme by scheme, to allow colour matching to be undertaken.

Review of treatment options

The concluding documentation should consider the significance of the paint schemes and appropriate treatment options.

Colour matching

Historic paint films are often discoloured through deterioration of the pigments and binder, as well as through environmental factors and historic cleaning regimes. Therefore, colour matching is based not only on site evidence but also on the understanding of the materials gained during the investigation.

What are the benefits of paint research for your project?

Benefits of undertaking a considered and well planned campaign of architectural paint research include:

Project management

  • By providing clarity at the beginning of a project, architectural paint research can allow planning and budgeting of conservation and restoration work
  • Identification of technical issues with paint, such as latent incompatibility, performance and toxicity
  • Contribution to long-term conservation management plan
  • Underpinning options for conservation/ restoration

Enriching the interpretation of your site

  • Enhancement of the recorded archaeology of a site
  • Establishment of the chronology of decorative schemes
  • Creation of a narrative of changes to the structure and related decorative schemes
  • Evaluation of how changing fashion, economy and use of a heritage asset has impacted on the choice, quality and condition of decoration
  • Interpretation of the significance of the schemes identified
  • Dating of both paint schemes and architectural changes