Paint Analysis

Investigation, Analysis and Documentation

Revealing the original decoration buried under layers of paint, dirt or even false ceilings and drywall involves a scientific process of investigation, analysis and documentation. This consists of the following phases: noting the areas of loss and identifying the previous materials used; exposing the original decorative paint layer; capturing the design elements; and, analyzing the colors, types of material, and application techniques for various finishes. Colors are matched to the Munsell system of universal color standards.

A full materials analysis can be provided to identify existing materials and ensure compatibility between past and future coatings. The depth of investigation needed is determined on a project-by-project basis. All of the results from the investigation and analysis are compiled and bound into a permanent record of the original decorative scheme and serve as a guide for the decorative restoration.

CSS has found the following processes to be the most productive and rewarding for historic buildings.

Conditions Assessment
The starting point for planning interior painting is a professional survey of the existing conditions throughout the space. It is important to determine whether any paint failure is merely typical aging or whether underlying factors such as moisture infiltration or the application of incompatible coatings may need to be addressed to ensure longevity of the proposed project. Areas of loss are noted and previous materials are identified if possible with the naked eye. If decorative painting is being considered to enhance the interior architecture of the church, a historic paint investigation may be conducted simultaneously.

The historic paint investigation goes deeper into the history of the wall coatings and decoration. In many cases, the historic finishes investigation offers the first, exciting glimpse of the original decorative scheme commissioned by the founders of the parish. Most properties have had numerous renovations over the years, and the original decoration is buried under layers of paint, dirt, and possibly under entirely new surfaces, such as false ceilings and drywall. This essential tool for guiding an authentic decorative restoration includes an investigation, analysis and documentation of the historic finishes, which include the current and past paints, glazes, wallcoverings, varnishes and so on. The historic finishes analysis produces a permanent record of the designs, colors, materials and techniques that were originally used on the walls, ceilings, columns and other interior architectural elements of the space. In determining the composition of the layers of coatings, it also reveals more definitively any incompatibility in previous materials or surface preparation issues that affect longevity.

Historic Research
An investigation usually includes historic research—searching for old photographs, newspaper articles, records of past work in the space, and anything else that might reveal clues as to the past decorative schemes. For instance, news stories from the dedication of a church frequently contain detailed descriptions of the interior decoration. Vintage photographs often help to reveal past décor and can identify areas of contrast and reflective surfaces.

Exposure
To uncover the original designs, colors and finishes, “exposure windows" are created in sections large enough to determine the frequency of repetition and spacing of designs, as well as the manner of design applications in unique areas such as corners and centers. A variety of chemical and physical means are used to remove the non-original layers of paint one by one. The mildest solvent that is effective is employed, along with various chemical and mechanical techniques, to achieve a clear reading of each design.

Design Analysis
Tracings of the decorative designs are made on clear mylar and compiled into a comprehensive catalog. The conservator also interprets the sequence of stencil applications and the techniques used to apply the designs, based on his or her expertise in historic to modern techniques, styles, and finishes. The application of translucent glazes or opaque highlights are noted. Overall and detailed photographs are also taken throughout the investigation.

Color Analysis   
The initial color analysis begins onsite with direct observation and the use of a field microscope or loupe. For more in-depth analysis, core samples of representative paint layers may be taken from the site and analyzed in the laboratory. The mounted samples are sliced on a bias to reveal the “chromochronology”-- all of the paint strata and surface coatings in the order in which they were applied. The dirt layers between paint strata, also visible under the microscope, help identify which layers belong to a single decorative scheme and can tell relatively how long a scheme endured before repainting. Studying samples microscopically reveals truer paint color, beneath the surface discoloration. Fully documenting the sequence of paint adds cost, but the record is useful for future work and is strongly recommended by the National Trust for Historic Preservation.

The colors from the core sample and the exposure window are matched to the Munsell System of universal color standards. The Munsell codes include three numbers representing hue, value and chroma, for precise visual identification. Other analytic systems can be used in conjunction with Munsell to provide spectral data for colors as well. The final palette for many projects includes dozens of colors.
 
Media and Compatibility Analysis
Based on microscopic observation, chemical tests and other forms of analysis, the composition of the various paint layers can be analyzed. This is particularly important when incompatibilities identified in the initial survey are causing paint failures or delamination. If paint defects or possible adverse reactions among coatings or cleaning chemicals are suspected, advanced analysis (such as Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy) can be undertaken to identify all substances, including any possible byproducts from chemical reaction. Hazardous paint components, such as lead, can also be identified during the media analysis.

The comprehensive results from the investigation and analysis of the historic finishes are compiled and bound into a permanent record of the original decorative painting scheme and a guide for the decorative restoration. Copies are held by the owner, the local historical society, and the studio.