Architectural Paint Research (APR) refers to the systematic analysis of architectural finishes – typically paints and varnishes but also including gilding, decorative plasterwork, wood finishes, and wallpapers – to better understand the appearance of a building through time or at a particular period of significance. It is typically a combination of both field and laboratory work, and APR practitioners, sometimes called “paint analysts” or “paint consultants”, have combined skills in a range of fields including (but not limited to) historic preservation, art conservation, microscopy, materials science, and decorative painting.
Most often, the objective of APR is to identify the original, or ‘first-period’ scheme on the interior or exterior of a structure, but other target schemes can relate to a significant historical event or the occupancy of an important individual or group. APR can also shed light on the physical evolution of a structure or identify causes of paint failure. The identification of original materials in an early finish (for instance, pigments and binding media) can be essential to carrying out accurate replications and effective conservation treatments.
APR is usually carried out at the beginning of a restoration or conservation project, and can be requested by a preservation architect, museum professional, conservator, building owner or painting contractor. At the beginning of a project, paint analysts conduct historic and documentary research, which can yield clues about a building’s history and historic schemes. The analyst must also carry out on-site research, which can include micro-excavations of paint layers to identify locations with the most intact finish sequences, from which small samples may be collected. Samples ideally include a portion of the substrate with all attached finishes. Site-work can also include the larger-scale exposure of target schemes using chemical or mechanical methods to better understand the appearance of glazes, patterns and designs, such as stenciling or faux-wood graining. These are also known as “exposure windows” and are usually carried out at a later stage in the project.
In the laboratory, the paint analyst will use low-power (up to 50x magnification) and high-power microscopy (up to 1000x magnification) to study both unprepared and prepared cross-section paint samples using reflected visible and ultraviolet (UV) light. This allows one to determine the number and nature of layers, as well to characterize some materials including pigments, varnishes, glazes, and metal leaf. Other important conditions that are observed at this stage include grime and mold between layers, and evidence of scraping or the application of overpaint. As each sample is examined, the finish sequences are documented digitally or through written notes or sketches, which allows for their comparison to establish the general sequence and to identify the target layer(s). Once the target layer is identified, color matching can be carried out visually under the microscope using a color-corrected light source, or with a colorimeter or spectrophotometer. Matches are typically made to a standardized system such as Munsell, and to a commercial paint line.
Depending on the project, it may be necessary to identify materials such as pigments, binding media, varnishes, or the type of metallic leaf. In this case additional analyses can be carried out including microchemical tests, fluorochrome staining, polarized light microscopy (PLM), scanning-electron microscopy with energy-dispersive spectroscopy (SEM-EDS), gas chromatography-mass spectrometry (GC-MS), or Fourier-transform infrared spectroscopy (FT-IR).
Documentation is key to any APR project and paint analysts prepare detailed analytical reports that include a concise, objective description of the findings supported by photomicrographs, analytical data, and color matches. The analyst may also provide recommendations for replication, exposure, or preservation of early finishes. These reports become a substantial part of the site documentation, guide future preservation efforts, and serve to enhance the overall understanding of a building’s decorative history.
The 6th International Architectural Paint Research (APR) Conference
The 6th International Architectural Paint Research (APR) Conference was held from March 15-17, 2017 in New York City on the historic campus of Columbia University. The 2017 APR conference was the sixth in a series of increasingly influential and groundbreaking conferences that bring together professionals from around the world to share their latest findings related to the analysis, research, conservation, and replication of historic finishes in the built environment. It engaged members of the vibrant, creative community of APR professionals, including paint analysts, painters and decorators, preservation architects, heritage managers, interior decorators, scholars, art conservators, and materials scientists.
Previous APR conferences have been held in Stockholm, Sweden (2014, hosted by the Swedish National Heritage Board), Lincoln, England (2010, hosted by the University of Lincoln), New York City (2008, hosted by Columbia University), Copenhagen (2005, hosted by the National Museum of Denmark), and London (2000, hosted by English Heritage). These conferences attracted 150-200 participants from countries around the world including the United States, Canada, the United Kingdom, Scandinavia, Belgium, the Netherlands, the Czech Republic, China, and Estonia. The most recent conference was attended by experts from over 14 countries. Attendance increases at each conference, and the expected attendance for the 2017 APR conference is between 200 and 250 APR professionals.
The 2017 APR conference papers will be published in an illustrated volume of peer-reviewed papers published by Archetype Publications Ltd, one of the world’s leading publishers of titles relating to technical art history and the conservation of art and antiquities. Previous post-conference titles published by Archetype include Architectural Finishes in the Built Environment (2009) and Standards in Architectural Paint Research (2014) have become required texts for the scholars of architecturally-engaged finishes and related fields.