A Proof of Concept c. 1982 (It Just Might Be Useful)

A couple weeks ago while clearing out some stuff from my basement workshop at my daughter’s house, I came across an experiment that is almost forty years old.

In the world of historical fine art one of the premier positions is held by “panel paintings,” or fine paintings composed on a solid wooden panel.  Given the age and prominence of these artworks, and the fact that they are unbalanced construction on an inherently unstable base given the presence of a precisely constructed laminar gesso and paint layer on the front side of the solid wood panel, caring for these artworks takes a high place in the preservation hierarchy.  Very early in my museum career I found this problem to be a fascinating one, and the data points of my career projects (when I was able to choose the projects to work on, which was most of the time) revealed that it was the quality of the problem that motivated me much of the time, not necessarily the notoriety of the artwork/furniture.  That explains my final project, which was the stabilization of a pair of wooden flag poles that encompassed a peculiar approach to addressing the problem of split timbers.

Back to panel paintings.

(Photo by H.L. Stokes via Wikipedia)

To counteract the unbalanced construction on a dynamic foundation, many, perhaps even most, ancient panel paintings have been augmented with a framework applied to the back side to both balance out the construction somewhat, but also to mitigate the tendency of the wood panel to warp.  Sometimes these added features, called “cradles,” are elegantly sophisticated.  Others are sophisticated and deleterious to the panel as the “floating” spines bind in the “pass through” blocks that are glued to the back side of the panel, inflicting new fractures to the panel along with the distortions as the panel attempts to expand and contract while the bound spines hold it in fixed dimensions, essentially a fixed cross-grain construction.  This problematic outcome caused the entire concept to be reexamined beginning about the time I was coming into the museum world and many panel paintings have been de-cradled.

Shortly after hearing a seminar presentation on the topic in 1982 I decided to construct a prototype integrating my understanding of what wood is and how it behaves with some out-of-the-box thinking.  Given that many of the old cradles were actually damaging the panel paintings, clearly a different approach was needed.  Believe me, the number of alternatives to traditional cradling were legion, and even the last panel paintings conference I attended included several novel and unrelated options.

So I made a full scale model to test some ideas I had rattling around my brain pan.  For starters I selected a less than premier piece of wood, it was literally a 2 x 12 resawn, planed, and glued together with hot hide glue into a “panel” approximately 20″ x 30″.

I then fabricated a series of “pass through” blocks with rounded contact points for the floating spines, which were themselves fairly lightweight, with the entire system glued to the back side of the panel.

You can see the construction of the blocks from this one that had been broken somewhere along the line.  I applied spray dry Teflon to both the rounded faces of the blocks and the floating spines, hoping that the shape and permanent dry lubrication would prevent the blocks and spines from binding together (Teflon being the slipperiest substance on earth).

After assembling the entire model and showing it to the paintings conservators at the museum (I was working at Winterthur Museum at the time) I set it aside and literally forgot about it for almost four decades.  Presumably it has been just sitting in the basement for all those years, responding to changes in the unregulated environment of the space.  Over the life of the panel there have been swings in humidity from 100% to maybe 25%, more than enough to impart hysteresis cycles a’plenty.

Much to my delight the assemblage has suffered no ill effects over the decades, so at least the concept proved sound.  The original construction is still perfectly flat and there are no instances of long-grain fracture to the wood.  Admittedly the panel is balanced in that both faces are raw wood open to the microclimate so there was very little impetus for severe warpage.  Still, I would have expected some loss in planarity if there was a flaw in the concept.  Nope, still dead flat.

Now that I have reclaimed the experiment I will create a simple paint scheme on the face to mimic the structure of a typical Renaissance panel painting and see how the experimental cradled panel responds over the years.  I will leave it sitting out of the way in the barn essentially exposed to the elements except for rain.  I’ll check back with it in, say, another 38 years to see how it did.  I’ll be 103 then, but I just got back from celebrating my Mom’s 103rd so that might not be too crazy.

If it still looks good then I’ll let someone in the museum world know about it.