Historical Note: Aqueous Chlorine Dioxide Bleaching at Christa Gaehde’s Studio in the 1990s

Abstract

AbstractThe preparation and use of aqueous 0.2% chlorine dioxide as it was practiced at the private conservation studio of paper conservator Christa M. Gaehde in the 1990s is described for the record. The bleach was used predominantly on prints printed in black printing inks on machinemade lignin-free paper. The treatment sequence involved washing in deionized water; immersion in the chlorine dioxide solution or a local brush application of the bleach in the print margins; rinsing in deionized water; neutralization of residual bleach by misting 1% sodium thiosulfate solution recto and verso; four rinsing baths in deionized water, the fourth one conditioned with calcium hydroxide to pH 9. Preparation of the bleach required special precautions in handling the sodium chlorite and formaldehyde.