Wickham-Valentine Conservation of 1812 Spirit Varnish
Richmond, VA: 1991
The 1812 Wickham House in Richmond is a splendid example of neoclassical architecture, with a subdued exterior hiding some of the nation's finest Neoclassical wall painting and a remarkable cantilevered central staircase. The home was built for attorney John Wickham, best known for leading the successful defense strategy that acquitted Vice President Aaron Burr of treason.
In the late 1980s, the Museum undertook a thorough restoration of the interior and exterior of the historic residence that uncovered many of the previously hidden neoclassical finishes that had been supplanted in the Victorian fervor of the Valentine period of ownership.
Project Goals
The museum's initial goal for restoration of the doors in the most important rooms was stripping and refinishing. Although the doors were in a deplorable state, I suggested that we first consider cleaning and polishing, but first I wanted an opportunity to research finishes from that period. I had just read an article by Don Williams at the Smithsonian Conservation Analytical Laboratory (CAL) on shellac (the basis of french polish). It seemed unlikely to me that the 1812 doors would have been french polished, as this is generally a late nineteenth century finish, but I needed to know more before proceeding.
When I contacted CAL to talk to Don Williams, he was not available and I ended up having a really interesting conversation with Mel Wachoviac. He believed that through careful examination and sampling it should be possible to determine the original finish and appearance of the doors. This was a fairly new concept in architectural circles, so I was pleased the Wickham's Director Eryl Platzer (Wentworth) agreed to allow Mel and I to conduct sampling and tests on small pieces of door trim.
Investigation
Mel arrived with a small ultraviolet lamp. When shined on the finish in a darkened room, we were amazed to find it glowing gray-green which indicated a spirit varnish, something like copal. Had it been shellac, it would have glowed a whitish-orange under that wavelength.
We selected several pieces of loose molding that appeared to have original finish and these went back to CAL. From the microscopy, it was clear the doors had a single application of this original finish. Had there been previous finish remnants, these would have been apparent in the pores of the wood.
The whole project changed direction as we realized we had degraded but intact 1812 spirit varnish. The doors were now dark and grimy with uneven sheen levels from dull to dead flat and areas around human contact such as at doorknobs were discolored and sticky to the touch from saponification of the finish in contact with oils from human skin. Each door had broken and missing pieces of trim.
Mel suggested we try an aqueous cleaner, Sorbitan (also known as one of the forms of Tween), that had removed the grime on the small pieces of trim in the lab, revealing a polished, translucent surface with a deep mahogany color. (We assumed this grime was largely coal residue.)
At this point, I returned to Eryl to ask for funding of the next stage: to test the cleaning methods and see what remained intact on the larger doors. At this point we were thinking we might be able to clean and uncover largely intact original finish, requiring only limited infill painting and repairs. She agreed.
From the Laboratory to the Workshop
Returning to Wickham, I set up a small shop on the second floor, took one of the doors and spent several days working with the Tween to remove the grime from both sides. The results were a little disappointing. Some areas were intact with a high gloss, but there were a lot of random flattened areas. Although the finish was largely continuous, it had microfissured, leading to a dull orange appearance, resulting from light-dispersion that obscured the grain.
In this process, though, we removed door hardware to find areas that had been protected since construction, giving us an idea of the original appearance.
Having no previous experience with spirit varnishes, I was intrigued to begin seeing the original brushstrokes, as well as drips and runs, that are evidence in this hot-applied finish that begins setting as it is laid down. Although the quality of the wood and workmanship of the doors was first-rate, the finish had a hastily-completed appearance, with in some cases runs diagonally across panels, suggesting they had been finished on edge.
Protecting the Original with a Conservation Coating
Realizing we had such a large quantity of intact original finish of this early era it was important to protect it and I suggested to Eryl that we develop a coating to reintroduce the translucency and sheen of the original spirit varnish while providing protection. This coating would be reversible and non-chemically-crosslinking with the original. The obvious choice was B67 (isobutylmethacrylate dissolved in mineral spirits), one of several resins used to protect old master paintings.
When tested on small pieces, B67 seemed to work well, but when brushed out on door panels, the flattened microfissured areas were not well saturated. Likely the molecular weight was too great to work into and fill the fissures. Mel talked to Richard Wolbers, a biochemist turned painting conservator based at Winterthur who recommended Larapol K-80 as an alternative.
Larapol K-80 is a ketone resin of very low viscosity even at high solids content. With a low molecular weight and structure similar to natural dammar resin, it dries to a very high gloss. Low molecular weight and low viscosity allowed it to flow into microfissures and saturate the fractured surface, providing gloss, as well as a base for the harder and more durable B67 coating. We now had a two-step protective system.
We tested this process on several door parts and it worked well. Two interested volunteers at the museum, Mike Scott and Susan Maye, were hired to assist with the project and we set up a small, lightly-equipped woodworking shop and finishing rooms on the second floor of Wickham-Valentine.
Scaling up the Concept to Work on the Doors
To make the necessary woodwork repairs, we had delicate mahogany rings turned to provide missing trim. The shop was well-stocked with dyes and stains so any given repaired part of a any door could be individually blended to match surrounding original woodwork. Susan and Mike began scaling up the cleaning, brush-applying Tween with a brush stiffened by being cut back to half-bristle length to allow for gentle scrubbing of the surface. The cleaner was then mopped up with cotton batting and the woodwork rinsed with deionized water. The saponified areas were particularly difficult to deal with as the finish was compromised. Even when these areas could finally be cleaned so they were no longer tacky, they were discolored and had areas devoid of finish.
I set out to scale up the finishing process and soon discovered that brush application of the Larapol would not be so simple. First it would not dissolve in stoddards solvent even after days in a magnetic stirrer. Adding a little xylene caused it to go into solution, but as it was applied to the doors, the finish would dwell for awhile then gradually creep back forming ridges. However in some areas it adhered well, leaving a beautiful presentation surface.
Theorizing that a thinner application with a rapidly evaporating solvent might allow it to stick and harden better, I brought in an HVLP sprayer and eventually managed to get a perfectly even coat by switching from stoddard's solvent to odorless mineral spirits with the addition of some xylene and naptha.
Working this process out took the better part of two weeks because I had to work out the exact viscosity that worked with the tips in the gun. I also discovered a challenge in working with the HVLP that I had never had to contend with previously using regular sprayers. The turbine in an HVLP both warms and dries the air, which had the effect of evaporating solvent, so it took a lot of experimenting and adjusting to get it to work.
Relying on the Finisher's Art
I followed the same process to apply B67 and to our dismay, the same thing happened. At first flowing out and looking perfect, the B67 also began pulling back into little puddles. The first solvent I added to get it to stick better and dry faster was naptha. This gave an even sheen, but the finish soon orange-peeled (dimpled like the skin of an orange). Over the next few weeks, I varied the proportions of mineral spirits and naptha with the B67. Some days it would flow, and others it wouldn’t.
I contacted the manufacturer (Rohm and Haas) about how temperature and humidity would effect the resin (they didn't know), but luckily the restoration project was nearing its end at this point and so the climate control system was reactivated. With the system balanced, we finally had consistent temperature and humidity. We began to realize the wide variations before might have been responsible for some of our problems, so I initiated a new round of tests, and in an environment that was consistently about 70 degrees with 55% humidity, I was able to vary only solvents to resin, changing the viscosity and HVLP gun settings, until I could achieve a consistent result.
Two to three weeks into this when still nothing was working right, I was in despair because I was dealing with processes and materials from a newer field for me (conservation of original finishes) and I didn't feel like I had the experience to make good judgements, so I wasn’t trusting my own knowledge. One day in speaking to an old chemist at a finishes manufacturer and telling him of my problems, he reminded me I had been a professional finisher for years, so I should not discount what I knew. Instead he told me to focus on thinking about how I would address it if I were using more conventional materials. In other words, these kinds of problems plague all finishers at times and they are solved by changing solvent, temperature and humidity, equipment, viscosity, distance of spray gun from the object, the speed at which you move... Going back in with this renewed trust in my ability to figure out the problems, I was able to make the application work.
Epilogue
This project back in 1991 opened up for me the possibilities in identifying original coatings and the sequences of subsequent layers and being able to uncover and protect them, rather than trying to replicate finishes, replacing them to what we think might have been the original appearance. Yet achieving this project was only possible because I had been a professional furniture finisher going back into the 1970s. This project was once again a reminder that the skills necessary to preserve art and architecture require both science and art. For me this was an exciting challenge to take those skills of a finisher and reapply them in new ways to the preservation of original finishes so the skill and knowledge of the original artisans remained for others to experience.