This article tells the story of how the Denver Art Museum conserved this map. To learn more about the map itself read this article. No longer on view.
History, Artistry & Science
Traditional conservation embodies what I like to refer to as the “holy trinity” of disciplines: history, artistic competency, and science. The marriage of these three areas make conservation stand apart from restoration—or simply making something look good or better.
History includes an understanding of the artist’s or maker’s intent and methodologies: their materials, manufacture, and process.
Artistic competency includes manual dexterity, color matching, and experience with the working properties of materials and application techniques.
The science aspect of conservation focuses on chemistry and physics, the composition and appearance of materials, how they deteriorate and how to slow that down. Technical and analytical tools and methods are often employed for identification of materials.
Photo documentation, or getting a visual record of the physical condition, is another step of conservation treatment. Typically the front and back are recorded before treatment. However, some of the painted colors were unstable as indicated by the cracked appearance and associated losses.
In addition to the creases being folded, there were numerous edge tears and areas of lifting between the primary and secondary supports. The map had unstable areas in the colorants: the gold, silver, and shell white had areas of flaking, lifting, and loss. In addition, the silver has tarnished to black. The copper-based pigments had literally disintegrated the paper in some areas.
How we were going to maneuver the map as well as reach the central areas needed to be considered.
We attached 3-inch foam tubing to the edges of the table so that the map would have a smooth, soft surface to drape against.
A large round “Sono” tube was wrapped with Marvelseal, an aluminum laminate. Rolling made it possible to safely turn the map from front to back as well as provides safe storage when not on display.
The unstable areas of media were consolidated using funori , a polysaccharide mucilage found in certain seaweed. Funori is cooked and diluted into a liquid state. Its adhesive properties and unobtrusive visual characteristics are well suited for consolidation of this media. It is typically warmed on a hot plate and applied by brush.
Following consolidation, a facing material was applied to where the copper-based pigment had corroded the paper, leaving it brittle and fragile. We used a lightweight cotton paper—more like a tissue—that had a heat-activated adhesive applied to one side. A warmed tacking iron was used to set the tissue in place.
For the purposes of this post, I have broken out the following treatment steps into individual phases although many were done in a simultaneous manner.
The creases were humidified using layers of spun polyester interleave, Gore-tex, damp blotter, and polyester film. Once the paper was relaxed and expanded we were able to open up the creases and folds and place them under dry blotter and weight to dry. We worked first on the front, then on the reverse.
On the reverse, we reinforced the creases using narrow strips of Japanese paper and wheat starch paste. This step was done in conjunction with humidification and flattening.
There were also old repairs on the reverse that had to be removed. The sticky, brown repair adhesive was softened by humidification using Gore-tex. The repair paper was mechanically removed using a stainless steel spatula and tweezers. The remaining adhesive residue was removed with the aid of a nylon spatula and absorbing with damp blotter.
Similar weight Japanese paper was carefully shaped to the area of loss and set in place using wheat starch paste.
We compensated for loss of color in damaged areas and to newly repaired areas of loss using pastel pencil. This material was selected for its matte appearance and good blending qualities.
The duration of treatment consisted of two full-time conservators and an assistant working on for just over two weeks.