CONSIDERATIONS OF THE EFFECT OF ERASERS ON COTTON FABRIC
THE REMOVAL OF PARTICULATE SOIL from a cotton surface is not always fully successful when done with a brush, vacuum, or compressed air. Erasers are often the treatment procedure next considered. In choosing an eraser, however, care should be taken to address its hardness in relation to the brittleness of fabric. In addition, the compatibility of the eraser composition with the textile and the design layer, as well as the eraser's effect on the fibers and the weave, must be considered. Inclusions, such as sulphur in the rubber-based erasers, and a dialkyl phthalate in the vinyl-based erasers, pose particular concern. Further research is certainly warranted in these areas.
The technique of using the eraser can be varied in order to achieve different results. Scrubbing the surface will raise the nap, leave more residue, and remove more soil, as opposed to gently pulling or rolling the eraser across the surface. Both the techniques of use and the choice of eraser are therefore essential in the success of the treatment, as is the thorough removal of the residue.
Table 10 presents a general summary of the test results from this experiment. The surface pH measurements of the cotton support were not deemed significant; the effect of the distilled water used to take the reading appeared to have a greater effect on the data than did the eraser crumbs themselves. The surface pH and cold extraction pH of the erasers are labeled unsatisfactory in the final tally if the reading fell below pH 6 or rose above pH 9. These extremes are considered potentially unsafe for the cellulose support.
Table 10 Summary of Results
Tristimulus and brightness values are summarized for both vacuumed and unvacuumed samples at the E stage of aging. In both tests, Kneaded Rubber and Pink Pearl are unsatisfactory: they cause the greatest darkening (low L value), reddening (+a value), and yellowing (+b value) of the textile. Absorene, Tapeten Reiniger, and Art Gum altered the cotton the least, while the vinyl erasers altered it a moderate amount. The results of the brightness measurements closely follow those of the tristimulus tests.
Each treatment situation involves a different set of limitations and criteria, and it is hoped that the results of this study will aid in that decision-making process. While it is not possible to wholeheartedly endorse any single product, one may conclude from these tests that erasers such as Kneaded Rubber and Pink Pearl may be considered inappropriate for use in conservation.
THE AUTHOR GRATEFULLY ACKNOWLEDGES Dr. Norbert Baer for his advice and guidance throughout this project, and extends warm thanks to Eneida Parreira, a fellow student at the Conservation Center, Institute of Fine Arts, New York University, for her work and enthusiasm during the initial phases of this experiment.