Joanna P. McMann presented the conservation treatment of a terrestrial globe from 1835 made by John and William Cary in London (UK). She, Janet Mason, and Sherry Guild completed the treatment as well as the treatment of its partner celestial globe at the Canadian Conservation Institute (CCI) over two years ending in 2013.
The terrestrial globe required treatment due to a fall out of a window. To quote from the abstract of this talk: “Impact upon landing forced the central pillar of the globe to move, pushing the sphere out at the North Pole and pulling it in at the South Pole. Extensive cracking, with losses of paper and plaster at both poles, had been repaired prior to the mid 1970’s with a generous application of polyvinyl acetate adhesive. An area of plaster loss, where the papier mâché foundation was indented, had been filled with a thick plaster.”
The damage meant that the globe was no longer spherical and could not rotate on its axis and the brass Meridian ring was distorted. Each hemisphere of the globe is covered in 18 half-split gores. Each of these gores is comprised of 20 degrees of longitude. Bodies of water were hand colored and the landmasses were either fully or partially colored. The globe was coated with a colophony varnish, which had discolored and become brittle over time.
One of the first steps in the treatment was figuring out how to support the globe. This was done by creating a stand made of a beanbag chair insert placed inside a ring to create a ‘nest’ that was then covered in polyester film. Once this problem was resolved the next tackled was how to remove the varnish. It was soluble in both ethanol and acetone, however these were not used due to concerns of staining the paper gores. Instead mechanical removal under stereomicroscopes was undertaken with ethanol and acetone used sparingly. This setup allowed up to four conservators to work on the globe at once!
Next the plaster repair was removed to inspect damage to the papier mâché. Then a small hole was cut in the papier mâché to insert a small camera into the globe and make sure there was not more structural damage hiding. This examination found the wooden support rod and the rest of the papier mâché to be in good condition. It also allowed the conservators to discover that the papier mâché globe was made of waste sheets of printed paper.
The next step was to examine the paper gores. Raman spectroscopy and a portable XRF were used to determine the chemical makeup of the colors. The brown color on the landmasses was found to contain copper. Following this a 5% Gellan gum was used to clean certain areas of the globe and to remove soluble copper II ions. Only certain areas were cleaned because the Gellan gum was found to remove colors in some areas.
The repairs at both Poles required the gores to be lifted and supported with pieces of wove paper before being rolled back out of the way. Polyester film was used as a barrier layer to protect the gores during the plaster repairs. The film was adhered to the gores using methylcellulose. Rhoplex W24 was used to repair cracks in the plaster and they found that Jade 403 had enough bulk to fill small losses. Flugger was chosen after testing to be used for the larger plaster fills. Once these steps were completed the gores were put back in place and repaired where needed. At the North Pole losses were filled with digitally printed fills made of Griffin Mill paper. The infills were sized with a 1.5% B type gelatin.
Next the entire globe was sized with five coats of a 2.5% gelatin in order to achieve the correct look after varnishing. There were six resins tested as potential varnishes: UVS (Regalrez 1094), Regalrez 1126, MS2A, Golden MSA, Soluvar, Paraloid B-72. In the end Paraloid B-72 in toluene was chosen and 10 coats were applied via sprayer.
Finally, when the globe was reconstructed the Meridian ring had to be flipped due to the distortion left from the fall out the window.
This was a very insightful talk into a vast and complex treatment of an interesting object. One thing I could not convey in my post without it becoming overly long was the amount of thought and testing of different options that went into every decision made in regards to this treatment.