Paint Analysis for Historic Buildings

Hey, that’s a neat old building. I wonder what it looked like new?”

Gathering paint samples for analysis
Gathering samples for analysis

I recently had the good fortune of attending a course at the National Center for Preservation Technology and Training in Natchitoches, Louisiana on paint analysis for historic buildings. The Town of Natchitoches is in northern Louisiana and is situated around historic cotton plantations. The movie “Steel Magnolias” was filmed in Natchitoches during the late 1980’s.

The course, Paint Analysis for Historic Buildings, was taught by David Arbogast. Mr. Arbogast is a renowned architectural conservator and paint specialist from Davenport, Iowa. During three intensive days we learned a great deal about the history of applied finishes (paints, stains, and clear coatings), architectural paint chemistry, the proper technique to restore deteriorated window mechanisms, how to collect field samples and analyze them in a laboratory and how to write up the findings.

Analyzing a paint sample to identify the paint layers and colours
Analyzing a sample to identify layers  and colours

During the second day, we collected 43 paint samples from the nearby Old Courthouse Museum. Most of our samples were smaller than the diameter of a pencil—more than enough for laboratory analysis. Using an optical stereo microscope, we examined each one. From these tiny specimens we were able to determine the number of layers of coatings applied to a particular area, and the colour of each layer. Observing the microscopic lines of atmospheric deposits (mostly soot and dirt) we established how frequently the building was painted. We documented each colour identified according to the Munsell System of Colour, a standardised colour palette book that does not change with time and fashion. It was amazing to see that such tiny samples could offer so much information about how a building evolved over its life.

It was a very intensive three days, but what I learned will be invaluable to my work as an architectural conservator or to anyone interested in knowing the evolution of coatings and colours used on their historic building.

Written by: Jim Nakonechny, Senior Restoration Officer

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