Understanding each project's historic preservation goal and
knowing what level of information needs to be collected to
achieve that goal is an important responsibility of the purchaser
of the service. Before someone is hired, the owner or manager
needs to decide if a thorough investigation of painted surfaces
is actually needed, and how to use the results when
one is done.
Specialists with both training and field experience conduct
paint investigations. These experts use sophisticated instruments
and procedures such as field sampling, cross-section analysis,
and fluorescent and chemical staining to learn about the components
and behaviors of historic paints. In addition, they utilize
written documentation, verbal research, and visual information
about past painting in the building in conjunction with findings
in the field.
Paint investigation can make several contributions to a project.
A complete analysis of the paint layers on surfaces within
a structure can tell a great deal about the sequence of alterations
that have occurred within a building, as well as potentially
providing ranges of dates for some of these changes.
By establishing a full sequence of paint layers (termed a
chromochronology), together with other research, alterations
of various building spaces and features can be associated
with specific paint layers. It is by establishing this association
that the correct layer is identified; when the correct layer
has been identified, the color may be matched.
In addition to its archeological value, paint analysis can
determine the types and colors of paint on a given surface
(identification of thin glazes, decorative paint schemes,
binders and pigments). Beyond color identification, then,
paint analysis is also recommended to diagnose causes of paint
failure. Knowing a paint binder can often explain causes as
well as guide appropriate preservation or conservation treatments.
Owners and managers should identify all of these needs before
deciding on the extent of analysis. For example, a complete
paint investigation is usually recommended as part of an historic
structure report. For buildings with little documentation,
additions and alterations can often be identified, and possibly
dated, through analysis. Often the use of such seemingly expensive
techniques can save money in the long run when determining
the history of building change.
It is possible to do some analysis on site; this is a much
simpler process that can be undertaken for less cost than
the complex laboratory procedures described above. However,
the usefulness of on-site analysis is limited and the results
will not be as precise as results from samples that are analyzed
in a laboratory with a good microscope.
Any shortcut approaches to paint analysis that do not follow
scientific procedures are generally not worth the expense.
In summary, if preservation and restoration treatments are
being undertaken, a complete investigation is recommended;
for a rehabilitation project, on-site analysis and color matching
may provide an adequate palette.