Title: In Situ Deacidification of Vernacular Wallpaper
Description: This thesis involved testing common proprietary deacidification sprays on vernacular wallpaper in situ. Inexpensive, mass-produced wallpaper is commonly overlooked by many conservators, whose efforts are more often directed toward the higher quality wallpapers that hang in the homes of historic luminaries. Cheaper wallpaper is just as relevant as these upscale counterparts, yet its materiality makes it more ephemeral and, therefore, in need of preservation efforts. Vernacular wallpaper was first produced in the middle of the 19th century, when wood pulp was introduced to the manufacturing process. A cheap alternative to cotton rags, wood pulp drove down the cost of production, making a traditionally expensive product available to nearly all Americans. The presence of wood pulp, however, also causes the wallpaper to deteriorate more quickly as the result of a higher acid content. Deacidification is a conservation method that was developed during the mid-20th century to preserve deteriorating library collections.

By neutralizing the acids present in paper and providing an alkaline reserve to protect against future acids, deacidification is believed to prolong the lifespan of wood pulp paper. Although paper conservators usually treat wallpaper in a laboratory setting, there are cases in which its removal from the wall may be deemed inappropriate. Professional laboratory conservation may also be prohibitively expensive for smaller, low budget house museums that often include vernacular wallpaper. Proprietary deacidification products were therefore chosen for testing. Vernacular wallpaper was provided by The Lower East Side Tenement Museum in New York City, where thousands of working class immigrants lived and worked between the 1860s and 1930s. The museum founders discovered the building in the 1980s with its residential floors exactly as they had been left when the building was condemned in 1935. The multiple layers of deteriorating wallpaper that remained in situ have become a defining feature of the museum and are preserved as integral architectural finishes.

For this reason, and because most of the wallpaper is extremely brittle, in situ treatment is preferred. Three spray products were tested on the wallpaper at the Tenement Museum. In order to be considered successful, these products were required to neutralize wallpaper samples without significantly altering their appearance. One product performed successfully on most samples, another achieved the highest pH measurements and also caused the most visual change, and the third was ineffective and inconsistent. Further research on the long-term effects of deacidification is necessary before any product can be recommended for use.