JAIC 1990, Volume 29, Number 2, Article 1 (pp. 97 to 115)
JAIC online
Journal of the American Institute for Conservation
JAIC 1990, Volume 29, Number 2, Article 1 (pp. 97 to 115)

THE EXAMINATION AND CONSERVATION TREATMENT OF THE LIBRARY OF CONGRESS HARKNESS 1531 HUEJOTZINGO CODEX

SYLVIA RODGERS ALBRO, & THOMAS C. ALBRO



7 TREATMENT OF THE MANUSCRIPT TEXT

THE SEWING structure was taken apart by cutting the threads. The threads were saved for study, and a sewing model was constructed to illustrate the original structure. A new collation of the manuscript was made. Once the leaves had been separated, they were housed temporarily in polyester film sleeves for protection during handling and to permit a complete study of watermarks without fingering the papers. The leaves were lightly dry cleaned with grated Staedtler Mars plastic eraser crumbs. Tests with water and water-alcohol mixtures indicated that the ink would sink further in the paper with any aqueous treatment, adding to the difficulty of reading the text, which already showed considerable strike-through. Aqueous treatment also risked creating more breaks in the sections of already-riddled paper due to the physical stresses of expansion and contraction. A nonaqueous treatment was selected to give the material an alkaline reserve. The leaves were immersed in methyl magnesium carbonate solution (Library of Congress 1977), and this treatment brought the surface pH of the papers up to a range of 6.6–7.4. Leaves with pressure–sensitive tapes were treated first with tetrahydrafuran (THF). After peeling the dried tape carrier away, the leaves were immersed in the solvent to remove the adhesive. To remove additional adhesive staining the leaves were sprayed with THF locally using an air-brush and the suction table. Treatment of these leaves with the methyl magnesium carbonate followed the stain removal.

Flexibility and ease of turning the leaves were considered top priorities in the practice of filling and mending. Edge tears and areas of loss in each leaf were repaired with Japanese papers, toned where necessary with Winsor & Newton acrylic pigments to match the original. With the help of a micrometer, layers of kizukishi, usumino, uda and tengujo paper were used to approximate the thickness of the manuscript paper (fig. 7). Determining the precise laminate structure for each fill was important so that new stresses would not be introduced when sections were sewn together again.

Fig. 7. Ink-damaged page (fig. 6) after treatment. Losses repaired with Japanese tissue in layers. Manuscript page treated with overall nonaqueous alkaline solution. Ink damage repaired with Library of Congress heat-set tissue.

A number of different techniques were investigated for mending the ink-damaged papers. Library of Congress heat-set tissue, toned with acrylic pigments, was selected as the most promising mending material for preserving the function and appearance of the paper (Library of Congress heat-set tissue, n.d.). Lens tissue was first coated with the acrylic adhesive and then dried. It was subsequently immersed in an acrylic pigment bath in order to attain the appropriate tone. The acrylic adhesive and thin tissue are amazingly strong and flexible, and the mends can be reversed in an alcohol bath. The heat-set mends were custom-cut with a needle and applied over both sides of the broken areas, using absolute alcohol to activate the adhesive. No heat was applied. Areas of heavily concentrated ink were mended on the opposite side of the page only. Enlargement prints made from the Library of Congress microfilm made in 1942 were useful in fitting loose fragments into place. These mends proved nearly invisible and could be restricted to the local areas of damage.


Copyright 1990 American Institute for Conservation of Historic and Artistic Works