8 TREATMENT OF THE SILKED PAGES

RESEARCH INTO the history of Library of Congress preservation practices uncovered the process used for the silking of documents in the 1940s. Manuscript papers were dampened and pressed, then pasted with a starch adhesive that also contained alum and white arsenic. The silk fabric was then applied to each side of the page and the whole pressed again (Fitzpatrick 1928, 36). As a result of this treatment the inks of the Huejotzingo manuscript on the leaves that had been silked were blurred and lightened and had sunk through to the opposite side of the page. Since these changes had already taken place, aqueous treatment of these leaves was considered. Testing indicated that the silking could be reversed in water. In water alone, however, the silk had to be peeled off, and a slight transfer of ink occurred. In addition, a substantial amount of adhesive remained on the paper. For these reasons, an alpha amylase enzyme solution was selected to detach the silk from the paper without transfer of ink (Segal and Cooper 1977).15 This treatment was very effective. After thorough rinsing and drying, the sheets could be examined closely. The paper was soft and gray-white in color compared to the cream color of the manuscript leaves that had never been treated. A strong impression of the silk weave remained on both sides of the paper. In order to improve the feel of the paper and strengthen it for subsequent rebinding, the leaves were sized by immersion in a 2% solution of warm gelatin after treatment in methyl magnesium carbonate solution. They remained a faded and worn version of their original character, demonstrating why silking has been replaced by other preservation techniques at the Library of Congress.

Losses and tears were mended with Japanese papers as described previously. In addition, each individual leaf was joined to its correct original conjugate with laminate mends along the spine edges, using the size of the adjacent folio as a model. At this point a new microfilm of the manuscript was made that clearly shows all of the text.