AIC's 47th Annual Meeting

Since the introduction of low-acyl gellan gum to the field in 2003 by conservators and scientists at the Conservation Department of the Istituto Centrale per il Restauro del Patrimonio Archivistico e Librario (ICRCPAL) in Rome, Italy, this gel has proven an extremely useful tool for controlled bathing of works of art on paper. A growing body of literature on the subject attests to the numerous benefits of gel washing: virtually no manipulation of the object during treatment, reduced swelling of the paper support, and even and efficient cleaning owing to the capillary action of the gel. This technique has made it possible to impart the benefits of an aqueous bath—strengthening by removal of acidic materials and improved aesthetic appearance—by gel washing objects that cannot withstand traditional immersion for various reasons (e.g. embrittled paper, lamellar supports, objects with sensitive media). Given the demonstrated success of gel bathing, the authors wondered whether or not the benefits observed in a routine gel wash could be translated to light bleaching, another conservation treatment that traditionally requires immersion of paper objects. During the summer of 2018, a series of studies were conducted at the J. Paul Getty Museum to test the efficacy of gellan gum as a water reservoir for light bleaching. Utilizing the abundant sunshine of Southern California as a light source, experiments investigated the following: light bleaching on gel vs. immersion in free water, light bleaching on alkaline gel vs. pH-neutral gel, and light bleaching with gel on one vs. both sides of the object. Later, at Library and Archives Canada (LAC), similar experiments were performed using artificial, high-power grow lights as a point of comparison to natural sunlight. This presentation will review the promising results of the light bleaching experiments described above. It will also summarize several case studies including overall light bleaching of a lithographic print and selective light bleaching of a foxed, photographic mount with locally applied gel. To the authors’ knowledge, this will be the first public presentation to explore the use of gel in light bleaching works on paper and photographs.