Colonial Williamsburg Digital Library

SO 1: Left (west) side of pediment, bottom (cyma reversa) trim, 1st and 2nd bricks to left (west) side of apex. Red-brown wash residues on brick surfaces.

SO 1e, visible light, 200x

SO 1e, UV light, 200x

SO 1c, visible light, 200x

SO 1c, UV light, 200x

During sampling, it was noted that the brick substrate was light orange in color and somewhat powdery. In the above photomicrograph, the brick substrate is visible at the bottom of the sample as a bright orange-red colored-material with large particles of aggregate. The surface of the brick appears rather worn and uneven, so it is possible that the first generation red-brown was applied after the brick was exposed for some time.

Generation 1 is a reddish-brown colored wash.

Generation 2 is a reddish-brown colored wash, which is much more red/orange in color than generation 1.

SO 2: Mortar joint in center of tympanum. Red-brown wash on mortar.

SO 2, visible light, 40x (enlarged)

SO 2, UV light, 40x (enlarged)

The surface of the joint is uneven, yellowed and has a dim autofluorescence in UV light, which suggests that the joint was already exposed for some time before the first generation red-brown wash was applied. This red-brown wash is very thin and fragmented in the cross-section, but it is the same as that found in sample SO 1 (previous page).

SO 3: Mortar joint at interface of top edge of tympanum and left (west) side of pediment, bottom edge of bottom (cyma reversa) trim. Red-brown washes on mortar.

SO 3b, visible light, 200x

SO 3b, UV light, 200x

SO 3a, visible light, 100x

SO 3a, UV light, 100x

Samples SO 3, SO 4, and SO 5 contain the same paint stratigraphies (see following pages). Four coating generations were identified. Like sample SO 2, the mortar joint in sample SO 3 is yellowed and worn at the surface, suggesting it was exposed for some time before the first generation red-brown was applied. This red-brown is the same as that found in samples SO 1-2, previous pages). Generation 2 is another red-brown paint, the same as that seen in sample SO 1).

Generation 3 is a coarsely ground gray paint. This contains black particles of various sizes in a grayish, translucent matrix that has a bright autofluorescence in UV light, suggestive of a resinous material. Generation 4 is composed of a white primer and a pale yellow paint. These coatings are opaque and have a dim autofluorescence in UV light, suggestive of an oil-based paint.

SO 4: Brick course just under the entablature, mortar joint under the third brick left (west) of the pilaster. Red-brown and yellow washes on mortar.

SO 4, visible light, 40x

SO 4, UV light, 40x

The paints in sample SO 4 are very disrupted and soiled, but this paint history is the same as that seen in sample SO 3 (previous page), taken from the tympanum, and sample SO 5 (next page), taken from the mortar joint between the pilaster and wall.

SO 5: Mortar joint between left (west) pilaster and brick wall. 20" down from pediment entablature. Same wash residues seen as SO 4.

SO 5, visible light, 100x

SO 5, UV light, 100x

Conclusions:

Four coating generations were identified on the brick exterior of the Secretary's Office. These do not appear to be first period finishes, as the bricks and mortar joints beneath the paints show evidence of exposure and wear before the extant coatings were applied. However, this does not suggest that the exterior of the Secretary's Office was not color-washed originally, only that evidence for these washes might have been lost through exterior exposure and wear. The most recent coating (generation 4) appears to have been the presentation surface at the time of the restoration (1939), so the preceding generations could be 19th-century, or even late 18th-century finishes.

Generations 1 and 2 are reddish-brown coatings. These are very powdery and loosely bound, which could result from extended periods of exposure and wear. Binding media analysis was not carried out, but these are most likely lime-based washes, although this would need to be confirmed with fluorochrome staining and/or instrumental techniques such as Fourier-transform infrared spectroscopy (FTIR) or gas-chromatography-mass spectrometry (GC-MS). Previous analyses of exterior brick washes on other Virginian 18th and early 19th-century buildings has determined that these coatings sometimes contain organic additives such as carbohydrates, oils, or proteins (Travers 2012, and Buck, Lounsbury, and Maul 2003).

Generation 3 is a gray coating, which appears to consist of black pigment particles in a resinous medium.

Generation 4 appears to be an oil-based white primer and pale yellow paint. The archival image of the south facade doorway (page 2), suggests that this could be the coating that was in existence when the building was restored in 1939.

Sample Preparation:

The samples were cast in mini-cubes of Extec Polyester Clear Resin (methyl methacrylate monomer), polymerized with the recommended amount of methyl ethyl ketone peroxide catalyst. The resin was allowed to cure for 24 hours under ambient light. After cure, the individual cubes were removed from the casting tray and sanded down using a rotary sander with grits ranging from 200 — 600 to expose the cross-section surface. The samples were then dry polished with silica-embedded Micro-mesh Inc. cloths with grits ranging from 1500 to 12,000, lending the final cross-section surface a glassy-smooth finish.

Microscopy and Documentation:

The cross-section samples were examined using a Nikon Eclipse 80i microscope equipped with an EXFO X-cite 120 fluorescence illumination system fiberoptic halogen light source. Samples were examined and photographed under visible and ultraviolet light conditions (excitation 330-380 nm, barrier filter 420nm), at 40-400x magnifications. Digital images were captured using a Spot Flex digital camera with Spot Advance (version 4.6) software. All images were recorded as 12.6 MB tiff files and stored on a hard drive in a folder titled "Secretary's Office" on Susan Buck's laboratory computer. A separate set of images are stored on the CWF digital database, accompanied by the appropriate metadata and a digital version of the final report.

SO 1a UV 100x

SO 1a VIS 100x

SO 1b UV 100x

SO 1b VIS 100x

SO 1c UV 200x

SO 1c VIS 200x

SO 1d UV 200x

SO 1d VIS 200x

SO 1e UV 200x

SO 1e VIS 200x

SO 2 UV 40x

SO 2 UV 100x

SO 2 VIS 40x

SO 2 VIS 100x

SO 3a UV 100x

SO 3a VIS 100x

SO 3b UV 200x

SO 3b VIS 200x

SO 4 UV 40x

SO 4 VIS 40x

SO 5a UV 100x

SO 5a VIS 100x

SO 5b UV 100x

SO 5b VIS 100x