RAC Update – 3/14/2006
Susan B. (along with Natasha L. and Christine T.), Norman W. and Irving S. were all on site the past week. Susan and her crew worked on finishing up the sampling for the first phase of the interior woodwork analysis and continued work on revealing surbases. Additional surbase profiles were found on the Dinsmore mantels that are presently in the education center (they are currently planned to be installed in Mr. Madison’s room and the Chamber above Mr. Madison’s room) and on one architrave from the Madison Chamber. While the reveals are not yet complete, they have so far discovered at least partial profiles for M100 (Dolly Chamber), M104 (Mr. Madison’s Room), M105 (Dining Room), M108 (Drawing Room), M200 (Rear Chamber), M201 (Dining Room Chamber) and M206 (Drawing Room Chamber). Susan and Christine will also look for profiles on architraves that were moved by the duPonts (which we will hopefully be able to be placed in their Madison context after the paint analysis report is finished), so the list of known profiles should continue to grow. The main weakness in the current group of profiles is lack of examples from the ca. 1765 spaces. To help get the profiles out to a larger audience, we are going to digitize and photograph each profile found by the reveals and assemble everything into a pdf file.
The flooring has also arrived from Mountain Lumber and it is great looking stuff. Blaze G. essentially hand picked every piece and the quality of wood is as good as the historic flooring found in situ. Every piece has also been cut (width and length) to replace a specific missing board.
Brick Conservation Update
Norman, Irving, Susan B., Ray Ca., Mark W. and myself all met on site to discuss preliminary findings of the brick conservation tests. As a caveat, all findings at this point are preliminary and Norman stresses that their conclusions could change with more thought. Basically what they have found, along with the other two labs who analyzed the bricks, is that freeze/thaw cycles are probably not the major issues in the brick deterioration. The bricks do, however, appear to be very weak with only around 500 to 600 psi required to crush them (to give some context, Norman said that a typical high heeled shoe has a force of around 400psi and that modern bricks can be engineered to withstand around 20,000psi). The strength of the bricks also appears to be reduced when wet. As a result, Norman and Irving are thinking that consolidating, which would help guard against freeze/thaw damage, may not be necessary. To further resolve the issue, they have proposed a test panel on the Mansion to determine the affect of the consolidants and how they react to the lime wash when exposed to the weather. The panel would be located below the water table on the north side (in what is currently thought to be a service area). The panel would be four feet by four feet and accommodate eight different scenarios using two formulations of the consolidant (one with a water repellant and one without). Basically the theory is to break up the panel into eight boxes of 1’ x 2’ and have the whole top half lime washed first while the bottom half would be consolidated first (one type of consolidant on each lower quadrant). After the consolidant has cured on the lower quadrants, then they will be partially lime washed (leaving a section exposed for a control) and the upper quadrant will be consolidated (again leaving a section of the quadrant unconsolidated to assess the impact of the untreated lime wash on the brick).
With this system, Norman and Irving feel confident that they can test all of the different permutations and be able to make recommendation that they are comfortable with. They also stress that now is the time to start testing and not once we see a problem (the consolidant takes around six months to apply and fully cure and we would not know how the lime wash would affect it until it was tested, which would take another six months). They also feel confidant that even if the testing shows that the consolidant will affect the adhesion of the lime wash to the brick substrate, that they will be able to use a high ph solution to breakdown the consolidant on the surface and to get the lime wash to stick. Ray C. also feels comfortable that he can remove any remains of the consolidated portions of the lime wash with a steam jenny (the temperature of the steam will break down the proteins in the lime wash and allow it to be removed).
All participants in the discussion, including John Mesick who was called later, feel as though the test panel would be a good idea, but they also wanted to get the RAC’s input as well.
Susan, Norman and Irving also discussed the formula for the lime wash and they all agreed on using casein (essentially milk paint) instead of hide glue for the protein component (the fact that casein is less soluble in water when cured was the main advantage).
The nail holes are currently being plotted and we will start excavating them this week.
The brick underpinning for the jacked chimney in the basement is being laid.
Wood for the decking has also arrived from Mountain Lumber and it is also extremely high quality material. Based on a paint sample taken by Susan B. from a re-used piece of historic colonnade decking, the colonnade deck will be painted a cream color. Interestingly, she has also found this color associated with the decking for the portico (except that there was clear evidence of sand being added), and it is currently proposed to paint all exterior decking (including the wings, where we have not found any surviving samples that contain Madison era paint layers) this color.
The major girts have all been installed and Bill is currently working on installing the joists.
A replacement purlin was installed where the northeastern dormer was cut into the roof by the duPonts. For the timber frame folks; it was installed with a couple of really interesting scarf joints that allowed the new member to be put in place without cutting through the mortise on the principle rafter. It also appears that John J. and Mark have found an alternative supplier for the cypress shingles, so the shingling should be able to continue without a problem.